Scattering in relativistic particle mechanics
International Nuclear Information System (INIS)
De Bievre, S.
1986-01-01
The problem of direct interaction in relativistic particle mechanics has been extensively studied and a variety of models has been proposed avoiding the conclusions of the so-called no-interaction theorems. In this thesis the authors studied scattering in the relativistic two-body problem. He uses the results to analyze gauge invariance in Hamiltonian constraint models and the uniqueness of the symplectic structure in manifestly covariant relativistic particle mechanics. A general geometric framework that underlies approaches to relativistic particle mechanics is presented and the kinematic properties of the scattering transformation, i.e., those properties that arise solely from the invariance of the theory under the Poincare group are studied. The second part of the analysis of the relativistic two-body scattering problem is devoted to the dynamical properties of the scattering process. Using general geometric arguments, gauge invariance of the scattering transformation in the Todorov-Komar Hamiltonian constraint model is proved. Finally, quantization of the models is discussed
Superconducting quasiparticle lifetimes due to spin-fluctuation scattering
International Nuclear Information System (INIS)
Quinlan, S.M.; Scalapino, D.J.; Bulut, N.
1994-01-01
Superconducting quasiparticle lifetimes associated with spin-fluctuation scattering are calculated. A Berk-Schrieffer interaction with an irreducible susceptibility given by a BCS form is used to model the quasiparticle damping due to spin fluctuations. Results are presented for both s-wave and d-wave gaps. Also, quasiparticle lifetimes due to impurity scattering are calculated for a d-wave superconductor
Spectral distortion due to scattered cold neutrons in beryllium filter
International Nuclear Information System (INIS)
Sakamoto, Yukio; Inoue, Kazuhiko
1980-01-01
Polycrystalline beryllium filters are used to discriminate the cold neutrons from the thermal neutrons with energies above Bragg cut-off energy. The cold neutron scattering cross section is very small, but the remaining cross section is not zero. Then the neutrons scattered once from the filter in the cold neutron energy region have chance of impinging on the outlet of filter. Those neutrons are almost upscattered and develop into thermal neutrons; thus the discriminated cold neutrons include a small spectral distortion due to the thermal neutrons. In the present work we have evaluated the effect on the cold neutron spectrum due to the repeatedly scattered and transmitted neutrons by using a Monte Carlo calculation method. (author)
Classical- and quantum mechanical Coulomb scattering
International Nuclear Information System (INIS)
Gratzl, W.
1987-01-01
Because in textbooks the quantum mechanical Coulomb scattering is either ignored or treated unsatisfactory, the present work attempts to present a physically plausible, mathematically correct but elementary treatment in a way that it can be used in textbooks and lectures on quantum mechanics. Coulomb scattering is derived as a limiting case of a screened Coulomb potential (finite range) within a time dependent quantum scattering theory. The difference in the asymptotic conditions for potentials of finite versus infinite range leads back to the classical Coulomb scattering. In the classical framework many concepts of the quantum theory can be introduced and are useful in an intuitive understanding of the quantum theory. The differences between classical and quantum scattering theory are likewise useful for didactic purposes. (qui)
Study of Compton broadening due to electron-photon scattering
Directory of Open Access Journals (Sweden)
Srinivasa Rao M.
2010-01-01
Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation. The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons. It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle. We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.
Study of Compton Broadening Due to Electron-Photon Scattering
Directory of Open Access Journals (Sweden)
Srinivasa Rao, M.
2010-06-01
Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation.The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons.It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle.We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.
Pulsar high energy emission due to inverse Compton scattering
Energy Technology Data Exchange (ETDEWEB)
Lyutikov, Maxim
2013-06-15
We discuss growing evidence that pulsar high energy is emission is generated via Inverse Compton mechanism. We reproduce the broadband spectrum of Crab pulsar, from UV to very high energy gamma-rays - nearly ten decades in energy, within the framework of the cyclotron-self-Compton model. Emission is produced by two counter-streaming beams within the outer gaps, at distances above ∼ 20 NS radii. The outward moving beam produces UV-X-ray photons via Doppler-booster cyclotron emission, and GeV photons by Compton scattering the cyclotron photons produced by the inward going beam. The scattering occurs in the deep Klein-Nishina regime, whereby the IC component provides a direct measurement of particle distribution within the magnetosphere. The required plasma multiplicity is high, ∼10{sup 6} – 10{sup 7}, but is consistent with the average particle flux injected into the pulsar wind nebula.
Neutron diffuse scattering in magnetite due to molecular polarons
International Nuclear Information System (INIS)
Yamada, Y.; Wakabayashi, N.; Nicklow, R.M.
1980-01-01
A detailed neutron diffuse scattering study has been carried out in order to verify a model which describes the property of valence fluctuations in magnetite above T/sub V/. This model assumes the existence of a complex which is composed of two excess electrons and a local displacement mode of oxygens within the fcc primitive cell. The complex is called a molecular polaron. It is assumed that at sufficiently high temperatures there is a random distribution of molecular polarons, which are fluctuating independently by making hopping motions through the crystal or by dissociating into smaller polarons. The lifetime of each molecular polaron is assumed to be long enough to induce an instantaneous strain field around it. Based on this model, the neutron diffuse scattering cross section due to randomly distributed dressed molecular polarons has been calculated. A precise measurement of the quasielastic scattering of neutrons has been carried out at 150 K. The observed results definitely show the characteristics which are predicted by the model calculation and, thus, give evidence for the existence of the proposed molecular polarons. From this standpoint, the Verwey transition of magnetite may be viewed as the cooperative ordering process of dressed molecular polarons. Possible extensions of the model to describe the ordering and the dynamical behavior of the molecular polarons are discussed
Light absorption and scattering mechanisms in laser fusion plasmas
International Nuclear Information System (INIS)
Barnes, C.; Estabrook, K.G.; Kruer, W.L.; Langdon, A.B.; Lasinski, B.F.; Max, C.E.; Randall, C.; Thomson, J.J.
1977-01-01
The picture of laser light absorption and scattering which is emerging from theory and computer simulation studies of laser-plasma interactions is described. On the subject of absorption, we discuss theoretical and experimental evidence that resonance absorption in a steepened density profile is a dominant absorption mechanism. Recent work also indicates the presence of critical surface ripples, which we study using two and three dimensional computer simulations. Predictions of hot electron spectra due to resonance absorption are described, as are effects of plasma outflow. We then discuss two regimes where stimulated scattering may occur. Brillouin scattering is expected in the underdense target blow-off, for long laser pulses, and is limited by ion heating. Raman scattering in the background gas of a reactor target chamber is predicted to be at most a 10 percent effect for 1 μm lasers
Quantum-mechanical scattering in one dimension
International Nuclear Information System (INIS)
Boya, Luis J.
2008-01-01
The purpose of this mainly pedagogical review is to fill a lacuna in the usual treatment of scattering in quantum mechanics, by showing the essential of it in the simplest, one-dimensional setting. We define in this situation amplitudes and scattering coefficients and deal with optical and Levinson' theorems as consequences of unitarity in coordinate or momentum space. Parity waves en lieu of partial waves, integral equations and Born series, etc., are defined naturally in this frame. Several solvable examples are shown. Two topics best studied in 1d are transparent potentials and supersymmetric quantum mechanics. Elementary analytical properties and general behaviour of amplitudes give rise to study inverse problems, that is, recovering the potential from scattering data. Isospectral deformations of the wave equation give relations with some nonlinear evolution equations (Lax), solvable by the inverse scattering method (Kruskal), and we consider the KdV equation as an example. We also refer briefly to some singular potentials, where, e.g., the essence of renormalization can be read off again in the simplest setting. The whole paper emphasizes the tutorial and introductory aspects
Inhibition of stimulated Raman scattering due to the excitation of stimulated Brillouin scattering
Zhao, Yao; Yu, Lu-Le; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming
2017-09-01
The nonlinear coupling between stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) of intense laser in underdense plasma is studied theoretically and numerically. Based upon the fluid model, their coupling equations are derived, and a threshold condition of plasma density perturbations due to SBS for the inhibition of SRS is given. Particle-in-cell simulations show that this condition can be achieved easily by SBS in the so-called fluid regime with kLλDDebye length [Kline et al., Phys. Plasmas 13, 055906 (2006)]. SBS can reduce the saturation level of SRS and the temperature of electrons in both homogeneous and inhomogeneous plasma. Numerical simulations also show that this reduced SRS saturation is retained even if the fluid regime condition mentioned above is violated at a later time due to plasma heating.
Density fluctuations due to Raman forward scattering in quantum plasma
Energy Technology Data Exchange (ETDEWEB)
Kumar, Punit, E-mail: punitkumar@hotmail.com; Singh, Shiv; Rathore, Nisha Singh, E-mail: nishasingh-rathore@yahoo.com [Department of Physics, University of Lucknow, Lucknow-226007 (India)
2016-05-06
Density fluctuations due Raman forward scattering (RFS) is analysed in the interaction of a high intensity laser pulse with high density quantum plasma. The interaction model is developed using the quantum hydrodynamic (QHD) model which consist of a set of equations describing the transport of charge, density, momentum and energy of a charged particle system interacting through a self-consistent electrostatic potential. The nonlinear source current has been obtained incorporating the effects of quantum Bohm potential, Fermi pressure and electron spin. The laser spectrum is strongly modulated by the interaction, showing sidebands at the plasma frequency. Furthermore, as the quiver velocity of the electrons in the high electric field of the laser beam is quit large, various quantum effects are observed which can be attributed to the variation of electron mass with laser intensity.
MIGRATION RATES OF PLANETS DUE TO SCATTERING OF PLANETESIMALS
International Nuclear Information System (INIS)
Ormel, C. W.; Ida, S.; Tanaka, H.
2012-01-01
Planets migrate due to the recoil they experience from scattering solid (planetesimal) bodies. To first order, the torques exerted by the interior and exterior disks will cancel, analogous to the cancellation of the torques from the gravitational interaction with the gas (Type-I migration). Assuming the dispersion-dominated regime and power laws characterized by indices α and β for the surface density and eccentricity profiles, we calculate the net torque on the planet. We consider both distant encounters and close (orbit-crossing) encounters. We find that the close and distant encounter torques have opposite signs with respect to α and β; and that the torque is especially sensitive to the eccentricity gradient β. Compared to Type-I migration due to excitation of density waves, the planetesimal-driven migration rate is generally lower due to the lower surface density of solids in gas-rich disk, although this may be partially or fully offset when their eccentricity and inclinaton are small. Allowing for the feedback of the planet on the planetesimal disk through viscous stirring, we find that under certain conditions a self-regulated migration scenario emerges, in which the planet migrates at a steady pace that approaches the rate corresponding to the one-sided torque. If the ratio of the local disk mass in planetesimals to planet mass is low, however, migration will stall. We quantify the boundaries separating the three accretion regimes.
Inverse scattering with supersymmetric quantum mechanics
International Nuclear Information System (INIS)
Baye, Daniel; Sparenberg, Jean-Marc
2004-01-01
The application of supersymmetric quantum mechanics to the inverse scattering problem is reviewed. The main difference with standard treatments of the inverse problem lies in the simple and natural extension to potentials with singularities at the origin and with a Coulomb behaviour at infinity. The most general form of potentials which are phase-equivalent to a given potential is discussed. The use of singular potentials allows adding or removing states from the bound spectrum without contradicting the Levinson theorem. Physical applications of phase-equivalent potentials in nuclear reactions and in three-body systems are described. Derivation of a potential from the phase shift at fixed orbital momentum can also be performed with the supersymmetric inversion by using a Bargmann-type approximation of the scattering matrix or phase shift. A unique singular potential without bound states can be obtained from any phase shift. A limited number of bound states depending on the singularity can then be added. This inversion procedure is illustrated with nucleon-nucleon scattering
A mechanical rotator for neutron scattering measurements
International Nuclear Information System (INIS)
Thaler, A.; Northen, E.; Aczel, A. A.; MacDougall, G. J.
2016-01-01
We have designed and built a mechanical rotation system for use in single crystal neutron scattering experiments at low temperatures. The main motivation for this device is to facilitate the application of magnetic fields transverse to a primary training axis, using only a vertical cryomagnet. Development was done in the context of a triple-axis neutron spectrometer, but the design is such that it can be generalized to a number of different instruments or measurement techniques. Here, we discuss some of the experimental constraints motivating the design, followed by design specifics, preliminary experimental results, and a discussion of potential uses and future extension possibilities.
Emittance growth due to beam-gas scattering
International Nuclear Information System (INIS)
Raubenheimer, T.O.
1992-06-01
The effect of beam-gas scattering on beam emittance is examined by deriving the beam distribution function. The distribution function is found by treating the beam-gas scattering as a filtered Poisson process and calculating the cumulants of the distribution. (author)
Neutron scattering and the search for mechanisms of superconductivity
DEFF Research Database (Denmark)
Aeppli, G.; Bishop, D.J.; Broholm, C.
1999-01-01
Neutron scattering is a direct probe of mass and magnetization density in solids. We start with a brief review of experimental strategies for determining the mechanisms of superconductivity and how neutron scattering contributed towards our understanding of conventional superconductors. The remai......Neutron scattering is a direct probe of mass and magnetization density in solids. We start with a brief review of experimental strategies for determining the mechanisms of superconductivity and how neutron scattering contributed towards our understanding of conventional superconductors....... The remainder of the article gives examples of neutron results with impact on the search for the mechanism of superconductivity in more recently discovered, 'exotic', materials, namely the heavy fermion compounds and the layered cuprates, (C) 1999 Elsevier Science B.V. All rights reserved....
Scattering Mechanism Extraction by a Modified Cloude-Pottier Decomposition for Dual Polarization SAR
Directory of Open Access Journals (Sweden)
Kefeng Ji
2015-06-01
Full Text Available Dual polarization is a typical operational mode of polarimetric synthetic aperture radar (SAR. However, few studies have considered the scattering mechanism extraction of dual-polarization SARs. A modified Cloude-Pottier decomposition is proposed to investigate the performance of the scattering mechanism extraction of dual-polarization SARs. It is theoretically demonstrated that only HH-VV SAR can discriminate the three canonical scattering mechanisms from an isotropic surface, horizontal dipole, and isotropic dihedral. Various experiments are conducted using 21 scenes from real datasets acquired by AIRSAR, Convair-580 SAR, EMISAR, E-SAR, Pi-SAR, and RADARSAT-2. Division of the dual-polarization H-α plane is experimentally obtained. The lack of cross-polarization induces the diffusion of scattering mechanisms and their overlap in the HH-VV H-α plane. However, the performance of HH-VV SAR for extracting scattering mechanisms is acceptable. Thus, HH-VV SAR is a suitable alternative to full-polarization SAR in certain cases. Meanwhile, the extraction performance of the other two dual-polarization SARs is badly degraded due to the lack of co-polarization. Therefore, HH-HV and HV-VV SARs cannot effectively extract the scattering mechanisms in the H-α plane.
Palasantzas, G.
2008-01-01
In this work we study the quality factor associated with dissipation due to scattering of shear horizontal surface acoustic waves by random self-affine roughness. It is shown that the quality factor is strongly influenced by both the surface roughness exponent H and the roughness amplitude w to
Electrical resistivity due to electron-phonon scattering in thin gadolinium films
International Nuclear Information System (INIS)
Urbaniak-Kucharczyk, A.
1988-01-01
The contribution to the electrical resistivity due to the electron-phonon scattering for the special case of h.c.p. structure is derived. The numerical results obtained for the case of polycrystalline gadolinum films show the resistivity dependence on the film thickness and the surface properties. (author)
Locating scatterers while drilling using seismic noise due to tunnel boring machine
Harmankaya, U.; Kaslilar, A.; Wapenaar, K.; Draganov, D.
2018-05-01
Unexpected geological structures can cause safety and economic risks during underground excavation. Therefore, predicting possible geological threats while drilling a tunnel is important for operational safety and for preventing expensive standstills. Subsurface information for tunneling is provided by exploratory wells and by surface geological and geophysical investigations, which are limited by location and resolution, respectively. For detailed information about the structures ahead of the tunnel face, geophysical methods are applied during the tunnel-drilling activity. We present a method inspired by seismic interferometry and ambient-noise correlation that can be used for detecting scatterers, such as boulders and cavities, ahead of a tunnel while drilling. A similar method has been proposed for active-source seismic data and validated using laboratory and field data. Here, we propose to utilize the seismic noise generated by a Tunnel Boring Machine (TBM), and recorded at the surface. We explain our method at the hand of data from finite-difference modelling of noise-source wave propagation in a medium where scatterers are present. Using the modelled noise records, we apply cross-correlation to obtain correlation gathers. After isolating the scattered arrivals in these gathers, we cross-correlate again and invert for the correlated traveltime to locate scatterers. We show the potential of the method for locating the scatterers while drilling using noise records due to TBM.
Supersymmetric quantum mechanics, phase equivalence, and low energy scattering anomalies
International Nuclear Information System (INIS)
Amado, R.D.; Cannata, F.; Dedonder, J.P.
1991-01-01
Supersymmetric quantum mechanics links two Hamiltonians with the same scattering (phase equivalence) but different number of bound states. We examine the Green's functions for these Hamiltonians as a prelude to embedding the two-body dynamics in a many-body system. We study the effect of the elimination of a two-body bound state near zero energy for the Efimov effect and Beg's theorem
Mechanisms of photon scattering on nucleons at intermediate energies
International Nuclear Information System (INIS)
L'vov, A.I.
1992-01-01
The principal question for studies of photon scattering by nucleons and nuclei is the following: Can photon scattering say something new about the structure of these objects in comparisons with photo- and electroproduction investigations? There is a general reason to believe that it is indeed the case. The Hamiltonian of the electromagnetic interaction has, in general, a piece quadratic in the electromagnetic field (the so-called two-photon seagull) which is seen only in two-photon processes, such as Compton scattering. Although the longitudnal part of this seagull is constrained by the gauge invariance, its transverse part is decoupled from the electromagnetic current and cannot be found in photoabsorption processes. The seagull S μν depends on explicit degrees of freedom included into the Hamiltonian. E.g. the non-relativisitic Schroedinger equation has an effective seagull due to the kinetic energy (p - eA) 2 /2M. Its parent relativistic Dirac equation has no seagull at all but has the same low-energy consequences due to additional degrees of freedom (antiparticles). In low-energy nuclear physics, with explicit meson exchanges and meson clouds (i.e. internal polarizability of the nucleons). By explicitly including the mesons into the Hamiltonian one can remove part of the seagulls. Then the rest of them will be a signal for degrees of freedom invisible in photoabsorption at energies of the considered scale. Some seagulls are related with t-channel exchanges in Compton scattering. The π o -exchange is seen in γp-scattering but has no counterpart in photoproduction off the proton. Thus, a complementary study of one- and two-photon reactions provides a way to look in a region of higher energies where direct studies via photoproduction processes may be hard
Surface scattering mechanisms of tantalum nitride thin film resistor.
Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan
2014-01-01
In this letter, we utilize an electrical analysis method to develop a TaN thin film resistor with a stricter spec and near-zero temperature coefficient of resistance (TCR) for car-used electronic applications. Simultaneously, we also propose a physical mechanism mode to explain the origin of near-zero TCR for the TaN thin film resistor (TFR). Through current fitting, the carrier conduction mechanism of the TaN TFR changes from hopping to surface scattering and finally to ohmic conduction for different TaN TFRs with different TaN microstructures. Experimental data of current-voltage measurement under successive increasing temperature confirm the conduction mechanism transition. A model of TaN grain boundary isolation ability is eventually proposed to influence the carrier transport in the TaN thin film resistor, which causes different current conduction mechanisms.
Scattering theory in quantum mechanics and asymptotic completeness
International Nuclear Information System (INIS)
Combes, J.M.
1977-07-01
A trial for describing the status of the scattering theory in quantum mechanics is given. The S matrix being defined, its unitarity is a consequence of the asymptotic completeness relation which is one of the mean problems discussed. It is shown that the multichannel scattering theory can be reformulated in the two Hilbert space formalism with a suitable choice of H 0 and J (one-body problem and N-body systems). Time-dependent methods try to solve directly the existence problem for wave-operators without recourse to resolvent methods. Emphasis is put on the fact that the success of such a method can be traced to its semi-classical aspect in the sense that the stationary phase method is a special way to single-out from the quantum dynamics the contribution of classical orbits
Non-Markovian dynamics of a qubit due to single-photon scattering in a waveguide
Fang, Yao-Lung L.; Ciccarello, Francesco; Baranger, Harold U.
2018-04-01
We investigate the open dynamics of a qubit due to scattering of a single photon in an infinite or semi-infinite waveguide. Through an exact solution of the time-dependent multi-photon scattering problem, we find the qubit's dynamical map. Tools of open quantum systems theory allow us then to show the general features of this map, find the corresponding non-Linbladian master equation, and assess in a rigorous way its non-Markovian nature. The qubit dynamics has distinctive features that, in particular, do not occur in emission processes. Two fundamental sources of non-Markovianity are present: the finite width of the photon wavepacket and the time delay for propagation between the qubit and the end of the semi-infinite waveguide.
Jolie, Wouter; Lux, Jonathan; Pörtner, Mathias; Dombrowski, Daniela; Herbig, Charlotte; Knispel, Timo; Simon, Sabina; Michely, Thomas; Rosch, Achim; Busse, Carsten
2018-03-09
We study chemically gated bilayer graphene using scanning tunneling microscopy and spectroscopy complemented by tight-binding calculations. Gating is achieved by intercalating Cs between bilayer graphene and Ir(111), thereby shifting the conduction band minima below the chemical potential. Scattering between electronic states (both intraband and interband) is detected via quasiparticle interference. However, not all expected processes are visible in our experiment. We uncover two general effects causing this suppression: first, intercalation leads to an asymmetrical distribution of the states within the two layers, which significantly reduces the scanning tunneling spectroscopy signal of standing waves mainly present in the lower layer; second, forward scattering processes, connecting points on the constant energy contours with parallel velocities, do not produce pronounced standing waves due to destructive interference. We present a theory to describe the interference signal for a general n-band material.
Jolie, Wouter; Lux, Jonathan; Pörtner, Mathias; Dombrowski, Daniela; Herbig, Charlotte; Knispel, Timo; Simon, Sabina; Michely, Thomas; Rosch, Achim; Busse, Carsten
2018-03-01
We study chemically gated bilayer graphene using scanning tunneling microscopy and spectroscopy complemented by tight-binding calculations. Gating is achieved by intercalating Cs between bilayer graphene and Ir(111), thereby shifting the conduction band minima below the chemical potential. Scattering between electronic states (both intraband and interband) is detected via quasiparticle interference. However, not all expected processes are visible in our experiment. We uncover two general effects causing this suppression: first, intercalation leads to an asymmetrical distribution of the states within the two layers, which significantly reduces the scanning tunneling spectroscopy signal of standing waves mainly present in the lower layer; second, forward scattering processes, connecting points on the constant energy contours with parallel velocities, do not produce pronounced standing waves due to destructive interference. We present a theory to describe the interference signal for a general n -band material.
Multiple Scattering in Random Mechanical Systems and Diffusion Approximation
Feres, Renato; Ng, Jasmine; Zhang, Hong-Kun
2013-10-01
This paper is concerned with stochastic processes that model multiple (or iterated) scattering in classical mechanical systems of billiard type, defined below. From a given (deterministic) system of billiard type, a random process with transition probabilities operator P is introduced by assuming that some of the dynamical variables are random with prescribed probability distributions. Of particular interest are systems with weak scattering, which are associated to parametric families of operators P h , depending on a geometric or mechanical parameter h, that approaches the identity as h goes to 0. It is shown that ( P h - I)/ h converges for small h to a second order elliptic differential operator on compactly supported functions and that the Markov chain process associated to P h converges to a diffusion with infinitesimal generator . Both P h and are self-adjoint (densely) defined on the space of square-integrable functions over the (lower) half-space in , where η is a stationary measure. This measure's density is either (post-collision) Maxwell-Boltzmann distribution or Knudsen cosine law, and the random processes with infinitesimal generator respectively correspond to what we call MB diffusion and (generalized) Legendre diffusion. Concrete examples of simple mechanical systems are given and illustrated by numerically simulating the random processes.
Relativistic scattering of fermions in quaternionic quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Hassanabadi, Hassan; Sobhani, Hadi [Shahrood University of Technology, Physics Department, Shahrood (Iran, Islamic Republic of); Banerjee, Abhijit [Krishnath College, Department of Mathematics, Murshidabad (India)
2017-09-15
In this article, we propose a quaternionic version of the Dirac equation in the presence of scalar and vector potentials. It has been shown that in complex limit of such an equation, the complex version of this equation can be covered. After setting a quaternionic form for the Dirac delta potential, scattering due to the considered interaction has been studied. Wave functions and discontinuity conditions of the problem considered have been derived in detail. Using the continuity equation, we have found a constraint implying the conservation law of the probability current. (orig.)
Scattering factor evaluation for internal dose assessment due to 60Co
International Nuclear Information System (INIS)
Gautam, Y.P.; Kumar, A.; Sharma, S.; Sharma, A.K.; Dube, B.; Hegde, A.G.
2008-01-01
Guidelines for the assessment of internal doses from monitoring suggest default measurement of uncertainties (i.e. lognormal scattering factor, SF) to be used for different types of monitoring data. In this paper, SF values have been evaluated for internal contamination due to 60 Co in two cases using whole body counting data. SF values of 1.04 and 1.03 were obtained for case I and II respectively while SF value of 1.03 was obtained using bioassay data for case I. SF evaluated is in good agreement with the default values given by IDEAS guidelines. (author)
H(10) due to radiation scattered in a 6 MV Linac for tomotherapy
International Nuclear Information System (INIS)
Vega C, H. R.; Esparza H, A.; Garcia R, M. G.; Reyes R, E.; Hernandez A, L.; Rivera, T.
2017-10-01
In order to determine the environmental equivalent dose (H(10)), due to the radiation that is dispersed over the body of a patient, 100 thermoluminescent dosimeters (TLD) around 6 MV TomoLINAC were used. The characteristics of the tomotherapy have the disadvantage that the shielding of the bunker increases considerably and for its design validated parameters are used for the conventional Linacs. In order to determine H(10) due to scattered radiation, measurements were made in the vicinity of the isocenter, while the 6 MeV photon beam was applied on a phantom. Also, TLDs were placed on the walls of the bunker that remained for 7 days, where approximately 50 patients were treated per day. At points close to the isocenter, the H(10) has an angular distribution caused by the phantom shape. In the bunker walls the highest H(10) was observed in the primary barriers. In the labyrinth, the impact of the scattered radiation was observed when measuring a greater value of the environmental equivalent dose in the wall furthest from the isocenter compared to the point located closest to it. (Author)
Polarization due to dust scattering in the planetary nebula Cn1-1
International Nuclear Information System (INIS)
Bhatt, H.C.
1989-01-01
The peculiar emission-line object Cn1-1 (=HDE330036=PK330+4 degrees 1), classified both as a symbiotic star and as a planetary nebula, was detected by the Infrared Astronomical Satellite (IRAS) as a strong source of far-infrared dust in the system. Bhatt and Mallik (1986) discussed the nature of the dust in Cn1-1 and argued that the object is a Type I protoplanetary nebula in a binary system. The argument presented here is that the polarization is intrinsic to Cn1-1 and is due to scattering by large (compared to interstellar) dust grains in the protoplanetary nebula that are asymmetrically distributed around the central star. The large degree of polarization (approximately 3 percent for the Cn1-1 distance of approximately 450 pc) with a large lambda(sub max) is naturally explained if it is caused by scattering by large dust grains in the Cn1-1 nebula. Since the H(sub alpha) line is also polarized at the same level and position angle as the continuum, the dust must be asymmetrically distributed around the central star. The morphology of the protoplanetary nebula in Cn1-1 may be bipolar. Thus, the polarization observations support the suggestion that Cn1-1 is a bipolar Type I planetary nebula
Possible Depolarization Mechanism due to Low Beta Squeeze
International Nuclear Information System (INIS)
Ranjbar, V.; Luccio, A.; Bai, M.
2008-01-01
Simulations reveal a potential depolarization mechanism during low beta squeeze. This depolarization appears to be driven by a spin tune modulation caused by spin precession through the strong low beta quads due to the vertical fields. The modulation of the spin tune introduces an additional snake resonance condition at ν s0 ± nν x - ν z l = integer which while the same numerology as the well known sextupole resonance, can operate in the absence of sextupole elements
Two-centre interference effects on the Thomas two-step scattering mechanisms
International Nuclear Information System (INIS)
Adivi, E Ghanbari
2010-01-01
The charge transfer process in the collision of fast protons with hydrogen molecules is theoretically investigated using the second-order Born approximation with correct boundary conditions. In addition to two first-order terms, the present calculations include the three second-order terms which correspond to the Thomas two-step scattering mechanisms. The interference effects, due to the scattering of the particles from two atomic centres, on the electron capture differential cross sections vary significantly with the orientation of the molecule and with the impact energy. After the averaging over all molecular orientations the interference patterns disappear but the Thomas peak becomes more pronounced. These patterns are also apparent in the differential cross sections as a function of the angle between the molecular axis and the incident beam direction. The integrated cross sections are calculated and the results are compared with available experimental data.
Elastic scattering of helium ions on 9Be nuclei and exchange mechanisms
International Nuclear Information System (INIS)
Burtebaev, N.; Dujsebaev, B.A.
1999-01-01
Among nuclei of 1p-shell 9 Be is an extremely deformed nucleus with cluster structure. This considerably impedes determination of nucleus-nucleus potential of interaction. The latter relates to the fact that cross-section of 3 He ion and ?-particle elastic scattering on light nuclei is formed by not only mechanism of mere potential nature but also by other processes of heavy breakaway and displacement as well as by effects of channel relation. Final probability of 6 He+ and 3 He and 5 He+? cluster existence in 9 Be nucleus can be determined in the processes of 3 He or ?-particle ion scattering. As a result, it can cause considerable growth of cross-section under backward angles due to exchange of impinging particle with identical cluster in a nucleus. In order to study the contribution of different mechanisms into formation of cross-section of elastic scattering of helium nuclides on 9 Be nucleus we have performed series of experiments in broad angular range at energies 8-20 MeV/nucleon at derived beams of isochronous cyclotron of the Institute of Nuclear Physics of Kazakhstan national Nuclear Centre
Pipa, Viktor; Vasko, Fedor; Mitin, Vladimir
1997-03-01
The low temperature energy and momentum relaxation rates of 2D electron gas placed near the free or clamped surface of a semi-infinit sample are calculated. To describe the electron-acoustic phonon interaction with allowance of the surface effect the method of elasticity theory Green functions was used. This method allows to take into account the reflection of acoustic waves from the surface and related mutual conversion of LA and TA waves. It is shown that the strength of the deformation potential scattering at low temperatures substantially depends on the mechanical conditions at the surface: relaxation rates are suppressed for the free surface while for the rigid one the rates are enhanced. The dependence of the conductivity on the distance between the 2D layer and the surface is discussed. The effect is most pronounced in the range of temperatures 2 sl pF < T < (2 hbar s_l)/d, where pF is the Fermi momentum, sl is the velocity of LA waves, d is the width of the quantum well.
Point spread function due to multiple scattering of light in the atmosphere
International Nuclear Information System (INIS)
Pękala, J.; Wilczyński, H.
2013-01-01
The atmospheric scattering of light has a significant influence on the results of optical observations of air showers. It causes attenuation of direct light from the shower, but also contributes a delayed signal to the observed light. The scattering of light therefore should be accounted for, both in simulations of air shower detection and reconstruction of observed events. In this work a Monte Carlo simulation of multiple scattering of light has been used to determine the contribution of the scattered light in observations of a point source of light. Results of the simulations and a parameterization of the angular distribution of the scattered light contribution to the observed signal (the point spread function) are presented. -- Author-Highlights: •Analysis of atmospheric scattering of light from an isotropic point source. •Different geometries and atmospheric conditions were investigated. •A parameterization of scattered light distribution has been developed. •The parameterization allows one to easily account for the light scattering in air. •The results will be useful in analyses of observations of extensive air shower
Mechanical Design of the NSTX High-k Scattering Diagnostic
International Nuclear Information System (INIS)
Feder, R.; Mazzucato, E.; Munsat, T.; Park, H.; Smith, D.R.; Ellis, R.; Labik, G.; Priniski, C.
2005-01-01
The NSTX High-k Scattering Diagnostic measures small-scale density fluctuations by the heterodyne detection of waves scattered from a millimeter wave probe beam at 280 GHz and λ = 1.07 mm. To enable this measurement, major alterations were made to the NSTX vacuum vessel and Neutral Beam armor. Close collaboration between the PPPL physics and engineering staff resulted in a flexible system with steerable launch and detection optics that can position the scattering volume either near the magnetic axis (ρ ∼ .1) or near the edge (ρ ∼ .8). 150 feet of carefully aligned corrugated waveguide was installed for injection of the probe beam and collection of the scattered signal in to the detection electronics
Mechanical Design of the NSTX High-k Scattering Diagnostic
Energy Technology Data Exchange (ETDEWEB)
Feder, R.; Mazzucato, E.; Munsat, T.; Park, H,; Smith, D. R.; Ellis, R.; Labik, G.; Priniski, C.
2005-09-26
The NSTX High-k Scattering Diagnostic measures small-scale density fluctuations by the heterodyne detection of waves scattered from a millimeter wave probe beam at 280 GHz and {lambda}=1.07 mm. To enable this measurement, major alterations were made to the NSTX vacuum vessel and Neutral Beam armor. Close collaboration between the PPPL physics and engineering staff resulted in a flexible system with steerable launch and detection optics that can position the scattering volume either near the magnetic axis ({rho} {approx} .1) or near the edge ({rho} {approx} .8). 150 feet of carefully aligned corrugated waveguide was installed for injection of the probe beam and collection of the scattered signal in to the detection electronics.
Scattering theory in quantum mechanics. Physical principles and mathematical methods
International Nuclear Information System (INIS)
Amrein, W.O.; Jauch, J.M.; Sinha, K.B.
1977-01-01
A contemporary approach is given to the classical topics of physics. The purpose is to explain the basic physical concepts of quantum scattering theory, to develop the necessary mathematical tools for their description, to display the interrelation between the three methods (the Schroedinger equation solutions, stationary scattering theory, and time dependence) to derive the properties of various quantities of physical interest with mathematically rigorous methods
Beam loss due to the aperture limitation resulting from intrabeam scattering
International Nuclear Information System (INIS)
Lee, S.Y.
1984-01-01
Diffusion equation is used to evaluate the beam loss in the presence of aperture limitation resulting from the intrabeam scattering. We discuss the effect of different boundary conditions. Satisfactory beam intensity can be maintained within the proposed RHIC operation time
International Nuclear Information System (INIS)
Broome, J.
1965-11-01
The programme SCATTER is a KDF9 programme in the Egtran dialect of Fortran to generate normalized angular distributions for elastically scattered neutrons from data input as the coefficients of a Legendre polynomial series, or from differential cross-section data. Also, differential cross-section data may be analysed to produce Legendre polynomial coefficients. Output on cards punched in the format of the U.K. A. E. A. Nuclear Data Library is optional. (author)
QED polarization asymmetries for e+e- scattering due to helicity flips
International Nuclear Information System (INIS)
Anders, T.B.; Sell, E.W.
1992-01-01
The polarization asymmetries for the e + e - scattering with polarized incoming of outgoing beams, which are proportional to the amplitudes φ 5 describing one helicity flip and φ 2 describing two helicity flips, have been calculated including their pure QED radiative corrections. These asymmetries are partly large and can be observed well at low energies. (orig.)
International Nuclear Information System (INIS)
Bjoernaa, N.; Havnes, O.; Jensen, J.O.; Trulsen, J.
1982-01-01
Precipitating protons in the energy range 1-100 keV are regularly present in the auroral ionosphere. These protons will produce enhancements in the intensity of the upshifted plasma line of the incoherently scattered spectrum. Similarly, secondary electrons produced by the precipitating protons give rise to enhanced plasma line intensities. For a quantitative discussion of these effects an experimentally measured proton flux is adapted and the corresponding secondary electron flux calculated. These particle fluxes are then applied in connection with the EISCAT radar facility. Both fluxes give rise to enhancements of the order of 20. It is possible to separate between proton and electron contributions to the enhanced plasma lines for scattering heights above the source region of secondary electrons. (Auth.)
Resistivity scaling due to electron surface scattering in thin metal layers
Zhou, Tianji; Gall, Daniel
2018-04-01
The effect of electron surface scattering on the thickness-dependent electrical resistivity ρ of thin metal layers is investigated using nonequilibrium Green's function density functional transport simulations. Cu(001) thin films with thickness d =1 -2 nm are used as a model system, employing a random one-monolayer-high surface roughness and frozen phonons to cause surface and bulk scattering, respectively. The zero-temperature resistivity increases from 9.7 ±1.0 μ Ω cm at d =1.99 nm to 18.7 ±2.6 μ Ω cm at d =0.9 0 nm, contradicting the asymptotic T =0 prediction from the classical Fuchs-Sondheimer model. At T =9 00 K, ρ =5.8 ±0.1 μ Ω cm for bulk Cu and ρ =13.4 ±1.1 and 22.5 ±2.4 μ Ω cm for layers with d =1.99 and 0.90 nm, respectively, indicating an approximately additive phonon contribution which, however, is smaller than for bulk Cu or atomically smooth layers. The overall data indicate that the resistivity contribution from surface scattering is temperature-independent and proportional to 1 /d , suggesting that it can be described using a surface-scattering mean-free path λs for 2D transport which is channel-independent and proportional to d . Data fitting indicates λs=4 ×d for the particular simulated Cu(001) surfaces with a one-monolayer-high surface roughness. The 1 /d dependence deviates considerably from previous 1 /d2 predictions from quantum models, indicating that the small-roughness approximation in these models is not applicable to very thin (<2 nm) layers, where the surface roughness is a considerable fraction of d .
Review of the inverse scattering problem at fixed energy in quantum mechanics
Sabatier, P. C.
1972-01-01
Methods of solution of the inverse scattering problem at fixed energy in quantum mechanics are presented. Scattering experiments of a beam of particles at a nonrelativisitic energy by a target made up of particles are analyzed. The Schroedinger equation is used to develop the quantum mechanical description of the system and one of several functions depending on the relative distance of the particles. The inverse problem is the construction of the potentials from experimental measurements.
Theoretical evaluation of self-shielding factors due to scattering resonances in foils
International Nuclear Information System (INIS)
Selander, W.N.
1960-06-01
A semi-analytical method is given for evaluating self-shielding factors for activation measurements which use thin foils having neutron scattering resonances. The energy loss by scattering in the foil is taken into account. The energy-dependent neutron angular distribution is expanded as a double series, the coefficients of which are (energy dependent) solutions of an infinite set of coupled integral equations. These are truncated in some suitable manner and solved numerically. The leading term of the series is proportional to the average, or effective flux in the activation sample. The product of this terra and the neutron capture cross-section is integrated numerically over the resonance to give the resonance self-shielding correction. Figure 4 shows resonance self-shielding factors derived in this mariner for the 132ev resonance in Co-59 and figure 5 shows similar results for the two Mn-55 resonances at 337ev and 1080ev. Self-shielding factors for 1/v capture are not significantly different from unity. (author)
Phononic thermal resistance due to a finite periodic array of nano-scatterers
Energy Technology Data Exchange (ETDEWEB)
Trang Nghiêm, T. T.; Chapuis, Pierre-Olivier [Univ. Lyon, CNRS, INSA-Lyon, Université Claude Bernard Lyon 1, CETHIL UMR5008, F-69621 Villeurbanne (France)
2016-07-28
The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects that are both subject to reciprocity. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the 5–100 K temperature range. It is observed that the associated thermal conductance has the same temperature dependence as that without phononic filtering.
Errors due to random noise in velocity measurement using incoherent-scatter radar
Directory of Open Access Journals (Sweden)
P. J. S. Williams
1996-12-01
Full Text Available The random-noise errors involved in measuring the Doppler shift of an 'incoherent-scatter' spectrum are predicted theoretically for all values of Te/Ti from 1.0 to 3.0. After correction has been made for the effects of convolution during transmission and reception and the additional errors introduced by subtracting the average of the background gates, the rms errors can be expressed by a simple semi-empirical formula. The observed errors are determined from a comparison of simultaneous EISCAT measurements using an identical pulse code on several adjacent frequencies. The plot of observed versus predicted error has a slope of 0.991 and a correlation coefficient of 99.3%. The prediction also agrees well with the mean of the error distribution reported by the standard EISCAT analysis programme.
Reduced thermal conductivity due to scattering centers in p-type SiGe alloys
International Nuclear Information System (INIS)
Beaty, J.S.; Rolfe, J.L.; Vandersande, J.; Fleurial. J.P.
1992-01-01
This paper reports that a theoretical model has been developed that predicts that the addition of ultra-fine, inert, phonon-scattering centers to SiGe thermoelectric material will reduce its thermal conductivity and improve its figure-of-merit. To investigate this prediction, ultra-fine particulates (20 Angstrom to 200 Angstrom) of boron nitride have been added to boron doped, p-type, 80/20 SiGe. All previous SiGe samples produced from ultra-fine SiGe powder without additions had lower thermal conductivities than standard SiGe, but high temperature (1525 K) heat treatment increased their thermal conductivity back to the value for standard SiGe. Transmission Electron Microscopy has been used to confirm the presence of occluded particulates and X-ray diffraction has been used to determine the composition to be BN
Photonic Rutherford scattering: A classical and quantum mechanical analogy in ray and wave optics
Selmke, Markus; Cichos, Frank
2013-06-01
Using Fermat's least-optical-path principle, the family of ray trajectories through a special (but common) type of a gradient refractive index lens n(r)=n0+ΔnR /r is solved analytically. The solution gives a ray equation r(ϕ) that is closely related to Rutherford scattering trajectories; we therefore refer to this refraction process as "photonic Rutherford scattering." It is shown that not only do the classical limits correspond but also the wave-mechanical pictures coincide—the time-independent Schrödingier equation and the Helmholtz equation permit the same mapping between the scattering of massive particles and optical scalar waves. Scattering of narrow beams of light finally recovers the classical trajectories. The analysis suggests that photothermal single-particle microscopy measures photonic Rutherford scattering in specific limits and allows for an individual single-scatterer probing. A macroscopic experiment is demonstrated to directly measure the scattering angle to impact parameter relation, which is otherwise accessible only indirectly in Rutherford-scattering experiments.
DEFF Research Database (Denmark)
Bekshaev, A. Ya; Angelsky, O. V.; Hanson, Steen Grüner
2012-01-01
between the forward- and backward-scattered momentum fluxes in the Rayleigh scattering regime appears due to the spin part of the internal energy flow in the incident beam. The transverse ponderomotive forces exerted on dielectric and conducting particles of different sizes are calculated and special......Based on the Mie theory and on the incident beam model via superposition of two plane waves, we analyze numerically the momentum flux of the field scattered by a spherical, nonmagnetic microparticle placed within the spatially inhomogeneous circularly polarized paraxial light beam. The asymmetry...
Energy Technology Data Exchange (ETDEWEB)
Hoogenboom, J.E. (Technische Hogeschool Delft (Netherlands))
1983-01-01
From the collision mechanics of inelastic discrete-level scattering several properties are derived for the secondary-neutron energy distribution (SNED) for inelastic continuum scattering, when conceived as scattering with continuously-distributed inelastic levels. Using assumptions about the level density and neutron cross section the SNED can be calculated and some examples are shown. A formula is derived to calculate from a given inelastic continuum SNED a function, which is proportional to the level density and the neutron cross section. From this relation further conditions follow for the SNED. Representations for the inelastic continuum SNED currently in use do not, in general, satisfy most of the derived conditions.
International Nuclear Information System (INIS)
Hoogenboom, J.E.
1983-01-01
From the collision mechanics of inelastic discrete-level scattering several properties are derived for the secondary-neutron energy distribution (SNED) for inelastic continuum scattering, when conceived as scattering with continuously-distributed inelastic levels. Using assumptions about the level density and neutron cross section the SNED can be calculated and some examples are shown. A formula is derived to calculate from a given inelastic continuum SNED a function, which is proportional to the level density and the neutron cross section. From this relation further conditions follow for the SNED. Representations for the inelastic continuum SNED currently in use do not, in general, satisfy most of the derived conditions. (author)
International Nuclear Information System (INIS)
Sugaya, Reija
1991-01-01
The velocity-space diffusion equation describing distortion of the velocity distribution function due to resonant wave-wave scattering of electromagnetic and electrostatic waves in an unmagnetized plasma is derived from the Vlasov-Maxwell equations by perturbation theory. The conservation laws for total energy and momentum densities of waves and particles are verified, and the time evolutions of the energy and momentum densities of particles are given in terms of the nonlinear wave-wave coupling coefficient in the kinetic wave equation. (author)
Second virial coefficient from the scattering operator in quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Cognola, G; Soldati, R; Zerbini, S [Libera Universita di Trento (Italy). Dept. di Matematica e Fisica
1977-12-17
A new expression is proposed for the second virial coefficient in quantum statistical mechanics in which there is no reference to the interaction potential, but only the S matrix appears. Then it is shown that our expression reproduces the well-known Beth-Uhlenbeck formula.
The mass transfer mechanism of fissile material due to fission
International Nuclear Information System (INIS)
Shafrir, N.H.
1975-01-01
A thin 252 Cf source of a mean thickness of an approXimately mono-atomic layer was used as an experimental model for the study of the basic mechanism of the knock-on process taking place in fissile material. Because of the thinness of the source it can be assumed that mainly primary knock-ons are formed. The ejection rate of knock-ons created by direct collisions between fission fragments and source atoms was measured as follows: the ejected atoms were collected in high vacuum on a catcher foil and 252 Cf determined by alpha spectroscopy using a silicon surface barrier detector. The number of 252 Cf ejected from the source in unit time could thus be determined while considering the anisotropy of ejection, geometry and counting efficiency. Taking into account the chemical composition of the source, eta(theor.) = 252 Cf atoms/fission was obtained. This result can be considered in reasonable agreement with experiment confirming that under the experimental conditions described, practically no knock-on cascade is formed. (B.G.)
Unified connected theory of few-body reaction mechanisms in N-body scattering theory
Polyzou, W. N.; Redish, E. F.
1978-01-01
A unified treatment of different reaction mechanisms in nonrelativistic N-body scattering is presented. The theory is based on connected kernel integral equations that are expected to become compact for reasonable constraints on the potentials. The operators T/sub +-//sup ab/(A) are approximate transition operators that describe the scattering proceeding through an arbitrary reaction mechanism A. These operators are uniquely determined by a connected kernel equation and satisfy an optical theorem consistent with the choice of reaction mechanism. Connected kernel equations relating T/sub +-//sup ab/(A) to the full T/sub +-//sup ab/ allow correction of the approximate solutions for any ignored process to any order. This theory gives a unified treatment of all few-body reaction mechanisms with the same dynamic simplicity of a model calculation, but can include complicated reaction mechanisms involving overlapping configurations where it is difficult to formulate models.
Formal scattering theory approach to S-matrix relations in supersymmetric quantum mechanics
International Nuclear Information System (INIS)
Amado, R.D.; Cannata, F.; Dedonder, J.P.
1988-01-01
Combining the methods of scattering theory and supersymmetric quantum mechanics we obtain relations between the S matrix and its supersymmetric partner. These relations involve only asymptotic quantities and do not require knowledge of the dynamical details. For example, for coupled channels with no threshold differences the relations involve the asymptotic normalization constant of the bound state removed by supersymmetry
Apocrypha of standard scattering theory (SST) and quantum mechanics of the de Broglie wave packet
International Nuclear Information System (INIS)
Ignatovich, V.K.
2001-01-01
It is shown that the Standard Scattering Theory (SST) does not correspond to the principles of Standard Quantum Mechanics (SQM). A more consistent theory is formulated. Some new results are obtained. Reflection and transmission of the de Broglie wave packet by thin layers of matter is considered
On the completeness of the natural modes for quantum mechanical potential scattering
Hoenders, B.J.
1979-01-01
The set of natural modes, associated with quantum mechanical scattering from a central potential of finite-range is shown to be complete. The natural modes satisfy a non-Hermitian homogeneous integral equation, or alternatively, are solutions of the time independent Schrödinger equation subject to a
Comprehensive study of the electron scattering mechanisms in 4H-SiC MOSFETs
Czech Academy of Sciences Publication Activity Database
Uhnevionak, V.; Burenkov, A.; Strenger, C.; Ortiz, G.; Bedel-Pereira, E.; Mortet, Vincent; Cristiano, F.; Bauer, A.J.; Pichler, P.
2015-01-01
Roč. 62, č. 8 (2015), s. 2562-2570 ISSN 0018-9383 Institutional support: RVO:68378271 Keywords : electron mobility * Hall effect * scattering mechanisms * SiC MOSFET Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.207, year: 2015
Mechanisms for the control of two-mode transient stimulated Raman scattering in liquids
International Nuclear Information System (INIS)
Spanner, Michael; Brumer, Paul
2006-01-01
Recent adaptive feedback control experiments demonstrated control of transient (i.e. nonimpulsive) Stokes emission from two closely spaced Raman-active modes in liquid methanol [e.g., B. J. Pearson et al., Phys. Rev. A 63, 063412 (2001)]. Optimally shaped pulses were found that selectively excited one of the two Stokes lines alone, optimized emission from both modes together, or completely suppressed all Stokes emission. Here, two general control mechanisms capable of affecting the ratio of intensities of the Stokes lines are identified. The first is operational when the duration of the pump pulse (t p ) is on the order of the collisional dephasing time (t d ). The ratio of the peak heights of the two Stokes lines can then be controlled by simply varying the duration and/or intensity of the pump pulse. The second operates when 1/t p is on the order of the energy separation of the two Raman modes, and hence when the two Raman modes are coupled due to overlapping nonlinear polarizations that drive the stimulated Raman scattering. In this regime, asymmetry in the spectral amplitudes within the pump pulse can control the asymmetry in the peak heights of the Stokes emission. Both these mechanisms have the same clear physical interpretation: shaping the pump pulse controls the nonlinear optical response of the medium, which in turn controls the stimulated Stokes emission, itself a χ (3) nonlinear effect. In neither mechanism does the ratio of peak heights in the Stokes spectrum reflect directly the ratio of excited-state populations associated with the two Raman modes, as was assumed in the experiments, nor does the control involve coherent quantum interference effects
Directory of Open Access Journals (Sweden)
Xi Shao
2016-03-01
Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.
Weaver, James; Lehmberg, Robert; Obenschain, Stephen; Kehne, David; Wolford, Matthew
2017-11-01
Stimulated rotational Raman scattering (SRRS) in the ultraviolet region (λ=248 nm) has been observed at the Nike laser over extended propagation paths in air during high power operation. Although this phenomenon is not significant for standard operating configurations at Nike, broadening of the laser spectrum and far-field focal profiles has been observed once the intensity-path length product exceeds a threshold of approximately 1 TW/cm. This paper presents experimental results and a new theoretical evaluation of these effects. The observations suggest that significantly broader spectra can be achieved with modest degradation of the final focal distribution. These results point to a possible path for enhanced laser-target coupling with the reduction of laser-plasma instabilities due to broad laser bandwidth produced by the SRRS.
International Nuclear Information System (INIS)
Fanack, C.; Boucher, I.; Heuraux, S.; Leclert, G.; Clairet, F.; Zou, X.L.
1996-01-01
Ordinary wave reflectometry in a plasma containing a localized density perturbation is studied with a 1-D model. The phase response is studied as a function of the wavenumber and position of the perturbation. It is shown that it strongly depends upon the perturbation shape and size. For a small perturbation wavenumber, the response is due to the oscillation of the cut-off layer. For larger wavenumbers, two regimes are found: for a broad perturbation, the phase response is an image of the perturbation itself; for a narrow perturbation, it is rather an image of the Fourier transform. For tokamak plasmas it turns out that, for the fluctuation spectra usually observed, the phase response comes primarily from those fluctuations that are localized at the cut-off. Results of a 2-D numerical model show that geometry effects are negligible for the scattering by radial fluctuations. (author)
National Research Council Canada - National Science Library
Pitarka, Arban; Helmberger, Don V; Ni, Sidao
2008-01-01
... into ongoing research for the development of simple empirical models of scattering that can be used in reducing the scatter in measures of Lg and coda wave magnitude and for discrimination purposes as well...
International Nuclear Information System (INIS)
Habara, Kosaku; Furukawa, Takashi; Shimozato, Tomohiro; Obata, Yasunori; Aoyama, Yuichi; Kawanami, Ryota; Hayashi, Naoki; Yasui, Keisuke; Matsuura, Kanji
2011-01-01
Image-guided radiation therapy using a gold marker-based tumor tracking technique provides precise patient setup and monitoring. However, the marker consists of high-Z material, and the resulting scattered rays tend to have adverse effects on the dose distribution of radiotherapy. The purpose of this study was to evaluate the dosimetric perturbation due to the use of a gold marker for radiotherapy in the lungs. The relative dose distributions were compared with film measurement, Monte Carlo simulation, and XiO calculation with the multi grid superposition algorithm using two types of virtual lung phantoms, which were composed of tough water phantoms, tough lung phantoms, cork boards, and a 2.0-mm-diameter gold ball. No dose increase and decrease in the vicinity of the gold ball was seen in the XiO calculations, although it was seen in the film measurements and the Monte Carlo simulation. The dose perturbation due to a gold marker cannot be evaluated using XiO calculation with the superposition algorithm when the tumor is near a gold marker (especially within 0.5 cm). To rule out the presence of such dose perturbations due to a gold marker, the distance between the gold marker and the tumor must therefore be greater than 0.5 cm. (author)
Experimental elucidation: microscopic mechanism of resonant X-ray scattering in manganite films
Ohsumi, H; Kiyama, T
2003-01-01
Resonant X-ray scattering experiments have been performed on perovskite manganite La sub 0 sub . sub 5 Sr sub 0 sub . sub 5 MnO sub 3 thin films, which are grown on three distinct perovskite with a coherent epitaxial strain and have a forced ferro-type orbital ordering of Mn 3d orbitals. Using an interference technique, we have successfully observed the resonant X-ray scattering signal from the system having the ferro-type orbital ordering and also revealed the energy scheme of Mn 4p bands. For the forced ferro-type orbital ordering system, the present results evidence that the resonant X-ray scattering signal originates from the band structure effect due to the Jahn-Teller distortion of a MnO sub 6 octahedron, and not from the Coulomb interaction between 3d and 4p electrons. (author)
Danailov, D; O'Connor, D J
2002-01-01
Recent experiments and our molecular-dynamics simulations indicate that the main signal of the angular scattering spectra of glancing incidence scattering are not affected by the thermal motion of surface atoms and can be explained by our row-model with averaged cylindrical potentials. At the ICACS-18 Conference [Nucl. Instr. and Meth. B 164-165 (2000) 583] we reported good agreement between experimental and calculated multimodal azimuthal angular scattering spectra for the glancing scattering of 10 and 15 keV [Nucl. Instr. and Meth. B 180 (2001) 265, Appl. Surf. Sci. 171 (2001) 113] He sup 0 beam along the [1 0 0] direction on the Fe(1 0 0) face. Our simulations also predicted that in contrast to the 2D angular scattering distribution, the 1D azimuthal angular distribution of scattered particles is very sensitive to the interaction potential used. Here, we report more detailed calculations incorporating the influence of terraces and surface steps on surface channeling, which show a reduction of the angular s...
Siddiqui-Jain, Adam; Hoj, Jacob P; Hargiss, J Blade; Hoj, Taylor H; Payne, Carter J; Ritchie, Collin A; Herron, Steven R; Quinn, Colette; Schuler, Jeffrey T; Hansen, Marc D H
2017-09-01
Stimulation of cultured epithelial cells with scatter factor/hepatocyte growth factor (HGF) results in individual cells detaching and assuming a migratory and invasive phenotype. Epithelial scattering recapitulates cancer progression and studies have implicated HGF signaling as a driver of cancer metastasis. Inhibitors of HGF signaling have been proposed to act as anti-cancer agents. We previously screened a small molecule library for compounds that block HGF-induced epithelial scattering. Most hits identified in this screen exhibit anti-mitotic properties. Here we assess the biological mechanism of a compound that blocks HGF-induced scattering with limited anti-mitotic activity. Analogs of this compound have one of two distinct activities: inhibiting either cell migration or cell proliferation with cell cycle arrest in G2/M. Each activity bears unique structure-activity relationships. The mechanism of action of anti-mitotic compounds is by inhibition of microtubule polymerization; these compounds entropically and enthalpically bind tubulin in the colchicine binding site, generating a conformational change in the tubulin dimer. Copyright © 2017 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D
2015-01-01
Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant
Energy Technology Data Exchange (ETDEWEB)
Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)
2015-06-15
Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant.
International Nuclear Information System (INIS)
Zeiger, E.M.
1978-01-01
New equations are presented for three- and four-body scattering, within the context of nonrelativistic quantum mechanics and a Hamiltonian scattering theory. For the three-body case Faddeev-type equations are presented which, although obtained from the rigorous Faddeev theory, only require two-body bound state wave functions and half-off-shell transition amplitudes as input. In addition, their effective potentials are independent of the three-body energy, and can easily be made real after an angular momentum decomposition. The equations are formulated in terms of physical transition amplitudes for three-body processes, except that in the breakup case the partial-wave amplitudes differ from the corresponding full amplitudes by a Watson final-state-interaction factor. Also presented are new equations for four-body scattering, obtained by generalizing our three-body formalism to the four-body case. These equations, although equivalent to those of Faddeev--Yakubovskii, are expressed in terms of singularity-free transition amplitudes, and their energy-independent effective potentials require only half-on-shell subsystem transition amplitudes (and bound state wave functions) as input. However, due to the detailed index structure of the Faddeev--Yakubovskii formalsim, the result of the generalization is considerably more complicated than in the three-body case
Energy loss mechanism for suspended micro- and nanoresonators due to the Casimir force
Gusso, André
2011-01-01
A so far not considered energy loss mechanism in suspended micro- and nanoresonators due to noncontact acoustical energy loss is investigated theoretically. The mechanism consists on the conversion of the mechanical energy from the vibratory motion of the resonator into acoustic waves on large nearby structures, such as the substrate, due to the coupling between the resonator and those structures resulting from the Casimir force acting over the separation gaps. Analytical expressions for the ...
Difference in x-ray scattering between metallic and non-metallic liquids due to conduction electrons
International Nuclear Information System (INIS)
Chihara, Junzo
1987-01-01
X-ray scattered intensity from a liquid metal as an electron-ion mixture is described using the structure factors, which are exactly expressed in terms of the static and dynamic direct correlation functions. This intensity for a metal is shown to differ from the usual scattered intensity from a non-metal in two points: the atomic form factor and the incoherent (Compton) scattering factor. It is shown that the valence electron form factor, which constitutes the atomic form factor in a liquid metal, leads to a determination of the electron-electron and electron-ion structure factors by combining the ionic structure factor. It is also shown that a part of the electron structure factor, which appears as the incoherent x-ray scattering, is usually approximated as the electron structure factor of the jellium model in the case of a simple metal. As a by-product, the x-ray scattered intensity from a crystalline metal and the inelastic scattering from a liquid metal are given by taking account of the presence of conduction electrons. In this way, we clarify some confusion which appeared in the proposal by Egelstaff et al for extracting the electron-electron correlation function in a metal from x-ray and neutron scattering experiments. A procedure to extract the electron-electron and electron-ion structure factors in a liquid metal is proposed on the basis of formula for scattered intensity derived here. (author)
Reconciling semiclassical and Bohmian mechanics. III. Scattering states for continuous potentials
International Nuclear Information System (INIS)
Trahan, Corey; Poirier, Bill
2006-01-01
In a previous paper [B. Poirier, J. Chem. Phys. 121, 4501 (2004)] a unique bipolar decomposition Ψ=Ψ 1 +Ψ 2 was presented for stationary bound states Ψ of the one-dimensional Schroedinger equation, such that the components Ψ 1 and Ψ 2 approach their semiclassical WKB analogs in the large-action limit. The corresponding bipolar quantum trajectories, as defined in the usual Bohmian mechanical formulation, are classical-like and well behaved, even when Ψ has many nodes or is wildly oscillatory. A modification for discontinuous potential stationary scattering states was presented in a second, companion paper [C. Trahan and B. Poirier, J. Chem. Phys.124, 034115 (2006), previous paper], whose generalization for continuous potentials is given here. The result is an exact quantum scattering methodology using classical trajectories. For additional convenience in handling the tunneling case, a constant-velocity-trajectory version is also developed
Quantum mechanical limit to plasmonic enhancement as observed by surface-enhanced Raman scattering.
Zhu, Wenqi; Crozier, Kenneth B
2014-10-14
Plasmonic nanostructures enable light to be concentrated into nanoscale 'hotspots', wherein the intensity of light can be enhanced by orders of magnitude. This plasmonic enhancement significantly boosts the efficiency of nanoscale light-matter interactions, enabling unique linear and nonlinear optical applications. Large enhancements are often observed within narrow gaps or at sharp tips, as predicted by the classical electromagnetic theory. Only recently has it become appreciated that quantum mechanical effects could emerge as the feature size approaches atomic length-scale. Here we experimentally demonstrate, through observations of surface-enhanced Raman scattering, that the emergence of electron tunnelling at optical frequencies limits the maximum achievable plasmonic enhancement. Such quantum mechanical effects are revealed for metallic nanostructures with gap-widths in the single-digit angstrom range by correlating each structure with its optical properties. This work furthers our understanding of quantum mechanical effects in plasmonic systems and could enable future applications of quantum plasmonics.
Modified random hinge transport mechanics and multiple scattering step-size selection in EGS5
International Nuclear Information System (INIS)
Wilderman, S.J.; Bielajew, A.F.
2005-01-01
The new transport mechanics in EGS5 allows for significantly longer electron transport step sizes and hence shorter computation times than required for identical problems in EGS4. But as with all Monte Carlo electron transport algorithms, certain classes of problems exhibit step-size dependencies even when operating within recommended ranges, sometimes making selection of step-sizes a daunting task for novice users. Further contributing to this problem, because of the decoupling of multiple scattering and continuous energy loss in the dual random hinge transport mechanics of EGS5, there are two independent step sizes in EGS5, one for multiple scattering and one for continuous energy loss, each of which influences speed and accuracy in a different manner. Further, whereas EGS4 used a single value of fractional energy loss (ESTEPE) to determine step sizes at all energies, to increase performance by decreasing the amount of effort expended simulating lower energy particles, EGS5 permits the fractional energy loss values which are used to determine both the multiple scattering and continuous energy loss step sizes to vary with energy. This results in requiring the user to specify four fractional energy loss values when optimizing computations for speed. Thus, in order to simplify step-size selection and to mitigate step-size dependencies, a method has been devised to automatically optimize step-size selection based on a single material dependent input related to the size of problem tally region. In this paper we discuss the new transport mechanics in EGS5 and describe the automatic step-size optimization algorithm. (author)
Dynamical basis sets for algebraic variational calculations in quantum-mechanical scattering theory
Sun, Yan; Kouri, Donald J.; Truhlar, Donald G.; Schwenke, David W.
1990-01-01
New basis sets are proposed for linear algebraic variational calculations of transition amplitudes in quantum-mechanical scattering problems. These basis sets are hybrids of those that yield the Kohn variational principle (KVP) and those that yield the generalized Newton variational principle (GNVP) when substituted in Schlessinger's stationary expression for the T operator. Trial calculations show that efficiencies almost as great as that of the GNVP and much greater than the KVP can be obtained, even for basis sets with the majority of the members independent of energy.
International Nuclear Information System (INIS)
Hamasha, K. M.; University of Tabuk, Tabuk
2010-01-01
Visible light scattering and absorption patterns were measured using a photoacoustic instrument at different locations in Irbid city. Measurments were perfoemed during the intervals 1-9 August 2007 and 7-13 October 2007 at the city center site (Palestine street) and the southern site (University Circle), respectively. The city center site is impacted by local urban and regional aerosols. The southern site is dominated by regional aerosols. Data from both sampling sites showed variety of diurnal light absorption and scattering patterns. During most of the measurement days, the highest light absorption peaks appeared in the morning, 7:00 - 9:30 AM, whereas the highest light scattering peaks appeared later, 9:30 - 11:00 AM. The earlier light absorption peaks are likely attributed to the elevated black carbon vehicular emission during the heavy traffic hours (rush hours) whereas, the later light scattering peaks are attributed to secondary aerosols generted in the atmosphere through photochmical reactions. The southern site (University Circle) exhibited a higher light scattering and a lower light absorption contribution to the light extinction, leading to a better visibility compared to the City Center site. The visibility is averaged at 44 km and 115 km at the city center site and southern site, respectively. (author).
A unified treatment of dynamics and scattering in classical and quantum statistical mechanics
International Nuclear Information System (INIS)
Prugovecki, E.
1978-01-01
The common formal features of classical and quantum statistical mechanics are investigated at three separate levels: at the level of L 2 spaces of wave-packets on GAMMA-space, of Liouville spaces B 2 consisting of density operators constructed from such wave-packets, and of phase-space representation spaces P of GAMMA distribution functions. It is shown that at the last level the formal similarities become so outstanding that all key quantities in P-space, such as Liouville operators, Hamiltonian functions, position and momentum observables, etc., are represented by expressions which to the zeroth order in (h/2π) coincide in the classical and quantum case, and in some instances coincide completely. Scattering theory on the B 2 Liouville spaces takes on the same formal appearance for classical and quantum statistical mechanics, and to the zeroth order in (h/2π) it coincides in both cases. This makes possible the formulation of a classical approximation to quantum scattering, and of a computational scheme for determining rhosup(out) from rhosup(in) for successive order of (h/2π). (Auth.)
DEFF Research Database (Denmark)
Dery, H.; Tromborg, Bjarne; Eisenstein, G.
2003-01-01
We describe a theoretical model for carrier-carrier scattering in an inverted semiconductor quantum well structure using a multisubband diagram. The model includes all possible nonvanishing interaction terms within the static screening approximation, and it enables one to calculate accurately...
DEFF Research Database (Denmark)
Nielsen, Stefan Kragh; Bindslev, Henrik; Salewski, Mirko
2010-01-01
Here we present collective Thomson scattering measurements of 1D fast-ion velocity distribution functions in neutral beam heated TEXTOR plasmas with sawtooth oscillations. Up to 50% of the fast ions in the centre are redistributed as a consequence of a sawtooth crash. We resolve various directions...
On mechanism of low-energy heavy ions scattering on a target surface with small atomic mass
Umarov, F F; Kudryashova, L B; Krylov, N M
2002-01-01
In the present work, an experimental study of low-energy (E sub 0 =20-500 eV) heavy Cs sup + ions scattering on target surfaces with small atomic masses (Al, Si, Ni) has been performed for more accurate definition of mechanism of scattering and evaluation of an opportunity for use of heavy ions scattering as a tool of surface layer analysis. It is shown that the dependence of the relative energies of scattered ions versus the initial energy E/E sub 0 (E sub 0) for Si (E sub b =4.64 eV/atom) and Ni (E sub b =4.43 eV/atom) approximately coincide despite the fact that the mass of Ni atom is twice as large as that of the Si atom mass. At the same time their binding energies E sub b are approximately equal to each other. It is found that the scattering angles of Cs sup + ions considerably exceed a limiting scattering angle theta sub l sub i sub m in a single collision. It has been established that the scattering of low-energy heavy ions by light targets is described by a non-binary mechanism of many-particle inter...
Correlating Scatter in Fatigue Life with Fracture Mechanisms in Forged Ti-6242Si Alloy
Sinha, V.; Pilchak, A. L.; Jha, S. K.; Porter, W. J.; John, R.; Larsen, J. M.
2018-04-01
Unlike the quasi-static mechanical properties, such as strength and ductility, fatigue life can vary significantly (by an order of magnitude or more) for nominally identical material and test conditions in many materials, including Ti-alloys. This makes life prediction and management more challenging for components that are subjected to cyclic loading in service. The differences in fracture mechanisms can cause the scatter in fatigue life. In this study, the fatigue fracture mechanisms were investigated in a forged near- α titanium alloy, Ti-6Al-2Sn-4Zr-2Mo-0.1Si, which had been tested under a condition that resulted in life variations by more than an order of magnitude. The crack-initiation and small crack growth processes, including their contributions to fatigue life variability, were elucidated via quantitative characterization of fatigue fracture surfaces. Combining the results from quantitative tilt fractography and electron backscatter diffraction, crystallography of crack-initiating and neighboring facets on the fracture surface was determined. Cracks initiated on the surface for both the shortest and the longest life specimens. The facet plane in the crack-initiating grain was aligned with the basal plane of a primary α grain for both the specimens. The facet planes in grains neighboring the crack-initiating grain were also closely aligned with the basal plane for the shortest life specimen, whereas the facet planes in the neighboring grains were significantly misoriented from the basal plane for the longest life specimen. The difference in the extent of cracking along the basal plane can explain the difference in fatigue life of specimens at the opposite ends of scatter band.
Iqbal, N.; Choudhury, P. K.
2017-12-01
The paper deals with scattering of electromagnetic (EM) waves by perfectly magnetic conducting (PMC) cylinder coated with chiro-ferrite medium under the assumption of oblique angle of incidence wave with perpendicular polarization (transverse electric; TE). An on-demand (in respect of orientation) kind of conducting sheath helix structure is assumed to exist at the outer surface of cylinder. The effects of sheath helix orientation, along with the material parameters, such as chirality admittance and gyrotropy, on the echo width as well as the magnitude and phase of the electric and magnetic fields are investigated. Control on the anisotropic property remains greatly useful in obtaining the required optical response from the scatterer - the feature which would find fabulous sensing related applications.
International Nuclear Information System (INIS)
Sugaya, Reiji
1989-01-01
General expressions of the matrix elements for nonlinear wave-particle scattering (nonlinear Landau and cyclotron damping) of electromagnetic and electrostatic waves in a homogeneous magnetized plasma are derived from the Vlasov-Maxwell equations. The kinetic wave equations obtained for electromagnetic waves are expressed by four-order tensors in the rotating and cartesian coordinates. No restrictions are imposed on the propagation angle to a uniform magnetic field, the Larmor radius, the frequencies, or the wave numbers. By electrostatic approximation of the dielectric tensor and the matrix elements the kinetic wave equations can be applied to the case in which two scattering waves are electrostatic or they are partially electrostatic. Further, the matrix elements in the limit of parallel or perpendicular propagation to the magnetic field are given. (author)
International Nuclear Information System (INIS)
Riess, J.; Duport, C.
1991-01-01
We report the first numerical results (with realistic parameter values) for the time evolution of a scattered Landau function in a model system. They give a striking illustration for the Hall velocity increase beyond the classical value of the conduction electrons in the quantum Hall regime. This phenomenon, which is crucial for the integer quantum Hall effect, is caused by a special kind of nonclassical particle dynamics induced by disorder and cannot be described by linear response theory
Energy Technology Data Exchange (ETDEWEB)
Ramos, Daniel, E-mail: daniel.ramos@csic.es; Frank, Ian W.; Deotare, Parag B.; Bulu, Irfan; Lončar, Marko [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)
2014-11-03
We investigate the coupling between mechanical and optical modes supported by coupled, freestanding, photonic crystal nanobeam cavities. We show that localized cavity modes for a given gap between the nanobeams provide weak optomechanical coupling with out-of-plane mechanical modes. However, we show that the coupling can be significantly increased, more than an order of magnitude for the symmetric mechanical mode, due to optical resonances that arise from the interaction of the localized cavity modes with standing waves formed by the reflection from thesubstrate. Finally, amplification of motion for the symmetric mode has been observed and attributed to the strong optomechanical interaction of our hybrid system. The amplitude of these self-sustained oscillations is large enough to put the system into a non-linear oscillation regime where a mixing between the mechanical modes is experimentally observed and theoretically explained.
DEFF Research Database (Denmark)
Uskov, Alexander; Protsenko, Igor E.; Mortensen, N. Asger
2014-01-01
We present a quantum mechanical approach to calculate broadening of plasmonic resonances in metallic nanostructures due to collisions of electrons with the surface of the structure. The approach is applicable if the characteristic size of the structure is much larger than the de Broglie electron...
(abstract) Sensitivity to Forest Biomass Based on Analysis of Scattering Mechanism
Way, JoBea; Bachman, Jennifer E.; Paige, David A.
1993-01-01
The estimation of forest biomass on a global scale is an important input to global climate and carbon cycle models. Remote sensing using synthetic aperture radar offers a means to obtain such a data set. Although it has been clear for some time that radar signals penetrate forest canopies, only recently has it been demonstrated that these signals are indeed sensitive to biomass. Inasmuch as the majority of a forest's biomass is in the trunks, it is important that the radar is sensing the trunk biomass as opposed to the branch or leaf biomass. In this study we use polarimetric AIRSAR P- and L-band data from a variety of forests to determine if the radar penetrates to the trunk by examining the scattering mechanism as determined using van Zyl's scattering interaction model, and the levels at which saturation occurs with respect to sensitivity of radar backscatter to total biomass. In particular, the added sensitivity of P-band relative to L-band is addressed. Results using data from the Duke Forest in North Carolina, the Bonanza Creek Experimental Forest in Alaska, Shasta Forest in California, the Black Forest in Germany, the temporate/boreal transition forests in northern Michigan, and coastal forests along the Oregon Transect will be presented.
International Nuclear Information System (INIS)
Requardt, M.
1984-01-01
In this paper we want to discuss the quantum mechanical measuring process within the realm of many body quantum theory. Our starting point is to consider this process as a special scattering phenomenon where within one of the partners, i.e. the many body measuring device, a collective coherent motion is induced by the interaction with the microobject. We start our investigation with the many body system having a large but finite number N of degrees of freedom which is the real situation. We then study in detail what will happen in the limit N->infinite, however emphasizing that this transition is actually only performed in the mind of the observer. This implies that certain tail events together with their phase correlations have to be truncated. We show that the dichotomy 'pure state' versus 'mixture' as outgoing scattering states will vanish in this limit in so far as it has no observable consequences provided one is only interested in the state of the microobject. Furthermore, we discuss the role of the observer, the notion of 'event', the relation between single preparation and ensemble picture, and the so-called 'reduction of the wave function' in the light of our approach, i.e. explaining the phenomena accompanying the measuring process in terms of many body quantum theory. (orig.)
Scattering mechanisms in shallow undoped Si/SiGe quantum wells
Directory of Open Access Journals (Sweden)
D. Laroche
2015-10-01
Full Text Available We report the magneto-transport study and scattering mechanism analysis of a series of increasingly shallow Si/SiGe quantum wells with depth ranging from ∼ 100 nm to ∼ 10 nm away from the heterostructure surface. The peak mobility increases with depth, suggesting that charge centers near the oxide/semiconductor interface are the dominant scattering source. The power-law exponent of the electron mobility versus density curve, μ ∝ nα, is extracted as a function of the depth of the Si quantum well. At intermediate densities, the power-law dependence is characterized by α ∼ 2.3. At the highest achievable densities in the quantum wells buried at intermediate depth, an exponent α ∼ 5 is observed. We propose and show by simulations that this increase in the mobility dependence on the density can be explained by a non-equilibrium model where trapped electrons smooth out the potential landscape seen by the two-dimensional electron gas.
Reconciling semiclassical and Bohmian mechanics. II. Scattering states for discontinuous potentials
International Nuclear Information System (INIS)
Trahan, Corey; Poirier, Bill
2006-01-01
In a previous paper [B. Poirier, J. Chem. Phys. 121, 4501 (2004)] a unique bipolar decomposition, Ψ=Ψ 1 +Ψ 2 , was presented for stationary bound states Ψ of the one-dimensional Schroedinger equation, such that the components Ψ 1 and Ψ 2 approach their semiclassical WKB analogs in the large action limit. Moreover, by applying the Madelung-Bohm ansatz to the components rather than to Ψ itself, the resultant bipolar Bohmian mechanical formulation satisfies the correspondence principle. As a result, the bipolar quantum trajectories are classical-like and well behaved, even when Ψ has many nodes or is wildly oscillatory. In this paper, the previous decomposition scheme is modified in order to achieve the same desirable properties for stationary scattering states. Discontinuous potential systems are considered (hard wall, step potential, and square barrier/well), for which the bipolar quantum potential is found to be zero everywhere, except at the discontinuities. This approach leads to an exact numerical method for computing stationary scattering states of any desired boundary conditions, and reflection and transmission probabilities. The continuous potential case will be considered in a companion paper [C. Trahan and B. Poirier, J. Chem. Phys. 124, 034116 (2006), following paper
A fish-like robot: Mechanics of swimming due to constraints
Tallapragada, Phanindra; Malla, Rijan
2014-11-01
It is well known that due to reasons of symmetry, a body with one degree of actuation cannot swim in an ideal fluid. However certain velocity constraints arising in fluid-body interactions, such as the Kutta condition classically applied at the trailing cusp of a Joukowski hydrofoil break this symmetry through vortex shedding. Thus Joukowski foils that vary shape periodically can be shown to be able to swim through vortex shedding. In general it can be shown that vortex shedding due to the Kutta condition is equivalent to nonintegrable constraints arising in the mechanics of finite-dimensional mechanical systems. This equivalence allows hydrodynamic problems involving vortex shedding, especially those pertaining to swimming and related phenomena to be framed in the context of geometric mechanics on manifolds. This formal equivalence also allows the design of bio inspired robots that swim not due to shape change but due to internal moving masses and rotors. Such robots lacking articulated joints are easy to design, build and control. We present such a fish-like robot that swims due to the rotation of internal rotors.
On mechanism of low-energy heavy ions scattering on a target surface with small atomic mass
Energy Technology Data Exchange (ETDEWEB)
Umarov, F.F. E-mail: farid1945@yahoo.com; Bazarbaev, N.N.; Kudryashova, L.B.; Krylov, N.M
2002-11-01
In the present work, an experimental study of low-energy (E{sub 0}=20-500 eV) heavy Cs{sup +} ions scattering on target surfaces with small atomic masses (Al, Si, Ni) has been performed for more accurate definition of mechanism of scattering and evaluation of an opportunity for use of heavy ions scattering as a tool of surface layer analysis. It is shown that the dependence of the relative energies of scattered ions versus the initial energy E/E{sub 0} (E{sub 0}) for Si (E{sub b}=4.64 eV/atom) and Ni (E{sub b}=4.43 eV/atom) approximately coincide despite the fact that the mass of Ni atom is twice as large as that of the Si atom mass. At the same time their binding energies E{sub b} are approximately equal to each other. It is found that the scattering angles of Cs{sup +} ions considerably exceed a limiting scattering angle {theta}{sub lim} in a single collision. It has been established that the scattering of low-energy heavy ions by light targets is described by a non-binary mechanism of many-particle interactions (simultaneous ion interaction with several target atoms). It has been shown that during the many-particle interactions the structure of energy spectra disappears; high relative energy of scattering ions and their dependence on energy of bombardment is observed. It has been found that the energy of scattered ions depends on binding energy, melting temperature and packing density of target atoms.
Energy Technology Data Exchange (ETDEWEB)
Silva, F. da [Associao EURATOM/IST, IPFN-LA, Instituto Superor Tecnico, Lisbon (Portugal); Heuraux, S. [Institut Jean Lamour, CNRS-Nancy-Universite, BP70239, Vandoeuvre-les-Nancy (France); Gusakov, E.; Popov, A. [Ioffe Institute, Polytekhnicheskaya, St Petersburg (Russian Federation)
2011-07-01
Forward-scattering under high level of turbulence or long propagation paths can induce significant effects, as predicted by theory, and impose a signature on the Doppler reflectometry response. Simulations using a FDTD (finite-difference time-domain) full-wave code have confirmed the main dependencies and general behavior described by theory but display a returned RMS power, at moderate amplitudes, half of the one predicted by theory due to the impossibility to reach the numerical requirements needed to describe the small wavenumber spectrum with the wanted accuracy.One justifying factor may be due to the splitting and enlargement of the probing beam. At high turbulence levels, the scattered power returning to the antenna is higher than the predicted by the theory probably due to the scattered zone being closer than the oblique cutoff. This loss of coherence of the wavefront induces a beam spreading, which is also responsible for a diminution of the wavenumber resolution. With a FDTD full-wave code we study the behavior of the probing beam under several amplitude levels of low wavenumber plasma turbulence, using long temporal simulations series to ensure statistical accuracy. (authors)
Hu, Zhongwei; Chulhai, Dhabih V; Jensen, Lasse
2016-12-13
Surface-enhanced hyper-Raman scattering (SEHRS) is the two-photon analogue of surface-enhanced Raman scattering (SERS), which has proven to be a powerful tool to study molecular structures and surface enhancements. However, few theoretical approaches to SEHRS exist and most neglect the atomistic descriptions of the metal surface and molecular resonance effects. In this work, we present two atomistic electrodynamics-quantum mechanical models to simulate SEHRS. The first is the discrete interaction model/quantum mechanical (DIM/QM) model, which combines an atomistic electrodynamics model of the nanoparticle with a time-dependent density functional theory description of the molecule. The second model is a dressed-tensors method that describes the molecule as a point-dipole and point-quadrupole object interacting with the enhanced local field and field-gradients (FG) from the nanoparticle. In both of these models, the resonance effects are treated efficiently by means of damped quadratic response theory. Using these methods, we simulate SEHRS spectra for benzene and pyridine. Our results show that the FG effects in SEHRS play an important role in determining both the surface selection rules and the enhancements. We find that FG effects are more important in SEHRS than in SERS. We also show that the spectral features of small molecules can be accurately described by accounting for the interactions between the molecule and the local field and FG of the nanoparticle. However, at short distances between the metal and molecule, we find significant differences in the SEHRS enhancements predicted using the DIM/QM and the dressed-tensors methods.
Nielsen, S. K.; Bindslev, H.; Salewski, M.; Bürger, A.; Delabie, E.; Furtula, V.; Kantor, M.; Korsholm, S. B.; Leipold, F.; Meo, F.; Michelsen, P. K.; Moseev, D.; Oosterbeek, J. W.; Stejner, M.; Westerhof, E.; Woskov, P.; TEXTOR Team
2010-09-01
Here we present collective Thomson scattering measurements of 1D fast-ion velocity distribution functions in neutral beam heated TEXTOR plasmas with sawtooth oscillations. Up to 50% of the fast ions in the centre are redistributed as a consequence of a sawtooth crash. We resolve various directions to the magnetic field. The fast-ion distribution is found to be anisotropic as expected. For a resolved angle of 39° to the magnetic field we find a drop in the fast-ion distribution of 20-40%. For a resolved angle of 83° to the magnetic field the drop is no larger than 20%.
Zhou, Wei; Sooryakumar, R.; King, Sean
2010-03-01
Low K dielectrics have predominantly replaced silicon dioxide as the interlayer dielectric material for interconnects in state of the art integrated circuits. To further reduce interconnect resistance-capacitance (RC) delays, additional reductions in the K for these low-K materials is being pursued by the introduction of controlled levels of porosity. The main challenge for porous low-K dielectrics is the substantial reduction in mechanical properties that is accompanied by the increased pore volume content needed to reduce K. We report on the application of the nondestructive Brillouin light scattering technique to monitor and characterize the mechanical properties of these porous films at thicknesses well below 200 nm that are pertinent to present applications. Observation of longitudinal and transverse standing wave acoustic resonances and the dispersion that accompany their transformation into traveling waves with finite in-plane wave vectors provides for the principal elastic constants that completely characterize the mechanical properties of these porous films. The mode amplitudes of the standing waves, their variation within the film, and the calculated Brillouin intensities account for most aspects of the spectra. The resulting elastic constants are compared with corresponding values obtained from other experimental techniques.
Brillouin light scattering studies of the mechanical properties of ultrathin low-k dielectric films
Link, A.; Sooryakumar, R.; Bandhu, R. S.; Antonelli, G. A.
2006-07-01
In an effort to reduce RC time delays that accompany decreasing feature sizes, low-k dielectric films are rapidly emerging as potential replacements for silicon dioxide (SiO2) at the interconnect level in integrated circuits. The main challenge in low-k materials is their substantially weaker mechanical properties that accompany the increasing pore volume content needed to reduce k. We show that Brillouin light scattering is an excellent nondestructive technique to monitor and characterize the mechanical properties of these porous films at thicknesses well below 200nm that are pertinent to present applications. Observation of longitudinal and transverse standing wave acoustic resonances and the dispersion that accompany their transformation into traveling waves with finite in-plane wave vectors provides for a direct measure of the principal elastic constants that completely characterize the mechanical properties of these ultrathin films. The mode amplitudes of the standing waves, their variation within the film, and the calculated Brillouin intensities account for most aspects of the spectra. We further show that the values obtained by this method agree well with other experimental techniques such as nanoindentation and picosecond laser ultrasonics.
Analysis of Mechanical Stresses Due to Voltage Dips in Fixed-Speed Wind Turbines
DEFF Research Database (Denmark)
Veluri, Badrinath; Santos-Martin, David; Jensen, Henrik Myhre
2011-01-01
stresses transients that may have a detrimental effect on the fatigue life of drivetrain system due to voltage dips. A rainflow cycle counting method for the stress history during the voltage dip event, analyses mean and amplitudes of the counted cycles, their occurrence moment and time of duration.......Voltage dips due to electrical grid faults generate transients of the generator electromagnetic torque which result in significant high stresses and noticeable vibrations for the wind turbine mechanical system. These events may also have a detrimental effect on the fatigue life of important...
International Nuclear Information System (INIS)
Ibrayeva, E.T.; Prmantayeva, B. A.; Kuterbekov, K. A.; Temerbayev, A. A.; Tleulessova, I. K.; Zhigalova, A.
2012-01-01
The purpose of the present work is studying the structure of various isotopes of lithium 6 , 7 , 8 , 9 Li and the mechanism of their interaction with protons in the processes of elastic scattering. Differential cross sections and analyzing powers for elastic proton scattering from nuclei of Li are calculated in the context of the Glauber diffraction theory. Comparison of the result of calculations with the experimental data has allowed to draw conclusions on the structure of the given nuclei and their interaction mechanisms. (Authors)
Reaction Mechanism and Structure Interplay for Proton Elastic Scattering from Halo Nuclei
International Nuclear Information System (INIS)
Crespo, R.; Johnson, R.C.
1999-01-01
The aim of this work is to clarify what properties of the projectile w.f. are relevant to describe elastic scattering of halo nuclei from stable nuclei. In particular, we examine how far elastic scattering observables probe correlation effects among projectile nucleons. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of 11 Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering cross sections can not, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead
Reaction mechanism and structure interplay for proton elastic scattering from halo nuclei
International Nuclear Information System (INIS)
Crespo, R.; Johnson, R. C.
1999-01-01
The aim of this work is to clarify what properties of the projectile w.f. are relevant to describe elastic scattering of halo nuclei from stable nuclei. In particular, we examine how far elastic scattering observables probe correlation effects among projectile nucleons. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of 11 Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering crosssections cannot, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead
Mechanical damage due to corrosion of parts of pump technology and valves of LWR power installations
International Nuclear Information System (INIS)
Hron, J.; Krumpl, M.
1986-01-01
Two types are described of uneven corrosion of austenitic chromium-nickel steel: pitting and slit corrosion. The occurrence of slit corrosion is typical of parts of pumping technology and valves. The corrosion damage of austenitic chromium-nickel steels spreads as intergranular, transgranular or mixed corrosion. In nuclear power facilities with LWR's, intergranular corrosion is due to chlorides and sulphur compounds while transgranular corrosion is due to the presence of dissolved oxygen and chlorides. In mechanically stressed parts, stress corrosion takes place. The recommended procedures are discussed of reducing the corrosion-mechanical damage of pumping equipment of light water reactors during design, production and assembly. During the service of the equipment, corrosion cracks are detected using nondestructive methods and surface cracks are repaired by grinding and welding. (E.S.)
Yue, Weisheng
2017-03-28
Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.
DEFF Research Database (Denmark)
Salewski, Mirko; Asunta, O.; Eriksson, L.-G.
2009-01-01
Auxiliary heating such as neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH) will accelerate ions in ITER up to energies in the MeV range, i.e. energies which are also typical for alpha particles. Fast ions of any of these populations will elevate the collective Thomson...... functions of fast ions generated by NBI and ICRH are calculated for a steady-state ITER burning plasma equilibrium with the ASCOT and PION codes, respectively. The parameters for the auxiliary heating systems correspond to the design currently foreseen for ITER. The geometry of the CTS system for ITER...... is chosen such that near perpendicular and near parallel velocity components are resolved. In the investigated ICRH scenario, waves at 50MHz resonate with tritium at the second harmonic off-axis on the low field side. Effects of a minority heating scheme with He-3 are also considered. CTS scattering...
International Nuclear Information System (INIS)
Lohmann, Bernd; Grum-Grzhimailo, Alexei N.; Kleinpoppen, Hans
2013-01-01
Derives parameters for electrons, photons, atoms, ions, molecules calculated from theory. Delivers the quantum mechanical knowledge of atomic and molecular physics. Presents state-of-the-art experiments in atomic and molecular physics and related theoretical approaches. The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or 'complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment 'complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The 'complete' experiment is, until today, hardly to perform
Energy Technology Data Exchange (ETDEWEB)
Lohmann, Bernd [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Grum-Grzhimailo, Alexei N. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics; Kleinpoppen, Hans
2013-07-01
Derives parameters for electrons, photons, atoms, ions, molecules calculated from theory. Delivers the quantum mechanical knowledge of atomic and molecular physics. Presents state-of-the-art experiments in atomic and molecular physics and related theoretical approaches. The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or 'complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment 'complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spirit of research in the direction of the complete experiment in atomic and molecular physics, considering some of the basic quantum processes: scattering, Auger decay and photo-ionization. It includes a description of the experimental methods used to realize, step by step, the complete experiment up to the level of the amplitudes and phases. The corresponding arsenal includes, beyond determining the total cross section, the observation of angle and spin resolved quantities, photon polarization and correlation parameters, measurements applying coincidence techniques, preparing initially polarized targets, and even more sophisticated methods. The 'complete' experiment is
International Nuclear Information System (INIS)
Kagan, V.D.; Karpenko, S.L.; Katilyus, R.
1989-01-01
Quenching of exciton luminescence in the constant electric field in cadmium sulfide at 1.8K, caused by impact ionization of free and delocalization of bound excitons by hot electrons is observed. When the field is increase up to 1 kW/cm continuous transfer from the Taundsen-Shockley law to the Davydov-Wolf one takes place. Among the samples studied pure samples are distinguished by the exciton spectrum, where, as it is shown in the work, the high-energy electrons lose quasipulse, radiating spontaneously piezophonons; in other samples scattering on impurities prevails. Theoretical processing of data on the bound exciton radiation line quenching in the moderate field region presents about 10 -4 values in pure and about 5x10 -6 cm ones in other samples for the 4 MeV energy electron free flight length. So, the optical methods used allowed one to determine high-energy electron relaxation mechanisms, prevailing in CdS at low temperature
International Nuclear Information System (INIS)
Sen, D.; Basu, A.N.; Sengupta, S.
1994-01-01
A critical analysis of the difference between the classical and quantum mechanical definitions of scattering cross sections for particles is presented. This leads to a clarification of the classical limit problem and suggests precise criteria for its validity. In particular these criteria are derived for both finite and infinite range potentials. (orig.)
Hayashi, Hiromitsu; Kuroki, Hideyuki; Higashi, Takaaki; Takeyama, Hideaki; Yokoyama, Naomi; Okabe, Hirohisa; Nitta, Hidetoshi; Beppu, Toru; Takamori, Hiroshi; Baba, Hideo
2017-07-01
Liver is an amazing organ that can undergo regenerative and atrophic changes inversely, depending on blood flow conditions. Although the regenerative mechanism has been extensively studied, the atrophic mechanism remains to be elucidated. To assess the molecular mechanism of liver atrophy due to reduced portal blood flow, we analyzed the gene expressions between atrophic and hypertrophic livers induced by portal vein embolization in three human liver tissues using microarray analyses. Thrombospondin (TSP)-1 is an extracellular protein and a negative regulator of liver regeneration through its activation of the transforming growth factor-β/Smad signaling pathway. TSP-1 was extracted as the most upregulated gene in atrophic liver compared to hypertrophic liver due to portal flow obstruction in human. Liver atrophic and hypertrophic changes were confirmed by HE and proliferating cell nuclear antigen staining and terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling. In an in vivo model with portal ligation, TSP-1 and phosphorylated Smad2 expression were continuously induced at 6 h and thereafter in the portal ligated liver, whereas the induction was transient at 6 h in the portal non-ligated liver. Indeed, while cell proliferation represented by proliferating cell nuclear antigen expression at 48 h was induced in the portal ligated liver, the sinusoidal dilatation and hepatocyte cell death with terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling was detectable at 48 h in the portal ligated liver. Obstructed portal flow induces persistent TSP-1 expression and transforming growth factor-β/Smad signal activation in atrophic liver. Thrombospondin-1 may be implicated in the liver atrophic change due to obstructed portal flow as a pro-atrophic factor. © 2016 The Japan Society of Hepatology.
International Nuclear Information System (INIS)
Wagner, P.
1976-04-01
Effects on graphite thermal conductivities due to controlled alterations of the graphite structure by impurity addition, porosity, and neutron irradiation are shown to be consistent with the phonon-scattering formulation 1/l = Σ/sub i equals 1/sup/n/ 1/l/sub i/. Observed temperature effects on these doped and irradiated graphites are also explained by this mechanism
Energy Technology Data Exchange (ETDEWEB)
Karamched, Phani S., E-mail: phani.karamched@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Wilkinson, Angus J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)
2011-01-15
Cross-correlation-based analysis of electron back-scatter diffraction (EBSD) patterns has been used to obtain high angular resolution maps of lattice rotations and elastic strains near carbides in a directionally solidified superalloy MAR-M-002. Lattice curvatures were determined from the EBSD measurements and used to estimate the distribution of geometrically necessary dislocations (GNDs) induced by the deformation. Significant strains were induced by thermal treatment due to the lower thermal expansion coefficient of the carbide inclusions compared to that of the matrix. In addition to elastic strains the mismatch was sufficient to have induced localized plastic deformation in the matrix leading to a GND density of 3 x 10{sup 13} m{sup -2} in regions around the carbide. Three-point bending was then used to impose strain levels within the range {+-}12% across the height of the bend bar. EBSD lattice curvature measurements were then made at both carbide-containing and carbide-free regions at different heights across the bar. The average GND density increases with the magnitude of the imposed strain (both in tension and compression), and is markedly higher near the carbides particles. The higher GND densities near the carbides (order of 10{sup 14} m{sup -2}) are generated by the large strain gradients produced around the plastically rigid inclusion during mechanical deformation with some minor contribution from the pre-existing residual deformation caused by the thermal mismatch between carbide and nickel matrix.
Crack growth retardation due to micro-roughness: a mechanism for overload effects in fatigue
International Nuclear Information System (INIS)
Suresh, S.
1982-01-01
A new mechanism for fatigue crack growth retardation following an overload is presented in this paper, based on a micro-roughness model. It is reasoned, with the aid of extensive experimental evidence available in the literature, that retardation following an overload is governed by the micromechanisms of near-threshold crack growth. This model is found to rationalize a number of hitherto unexplained experimental observations. Moreover, the present arguments, which suggest that plasticity-induced crack closure is not likely to be the primary mechanism for retardation following single overloads, do not exclude the role of residual stresses or blunting, but provide further mechanistic basis to account for the inconsistencies in the previous models. Additional sources of prolonged retardation, in terms of crack closure due to corrosion debris formed in moist environments, are suggested. It is pointed out that such environmental effects could play an important role in post-overload crack growth in certain alloy systems
Tavernelli, Ivano
2018-06-01
Self-interference embodies the essence of the particle-wave formulation of quantum mechanics (QM). According to the Copenhagen interpretation of QM, self-interference by a double-slit requires a large transverse coherence of the incident wavepacket such that it covers the separation between the slits. Bohmian dynamics provides a first step in the separation of the particle-wave character of matter by introducing deterministic trajectories guided by a pilot wave that follows the time-dependent Schrödinger equation. In this work, I present a new description of the phenomenon of self-interference using the geometrical formulation of QM introduced in Tavernelli (2016). In particular, this formalism removes the need for the concept of wavefunction collapse in the interpretation of the act of measurement i.e., the emergence of the classical world. The three QM formulations (Schrödinger, Bohmian, and geometrical) are applied to the description of the scattering of a free electron by a hydrogen atom and a double-slit. The corresponding interpretations of self-interference are compared and discussed.
Georgious, I. T.; Sun, C. T.
1992-01-01
The history of temperature rise due to internal dissipation of mechanical energy in insulated off-axis uniaxial specimens of the unidirectional thermoplastic composite (AS4/PEEK) has been measured. The experiment reveals that the rate of temperature rise is a polynomial function of stress amplitude: It consists of a quadratic term and a sixth power term. This fact implies that the specific heat of the composite depends on the stretching its microstructure undergoes during deformation. The Einstein theory for specific heat is used to explain the dependence of the specific heat on the stretching of the microstructure.
A mechanical velocity selector for a small angle scattering instrument on a pulsed neutron source
International Nuclear Information System (INIS)
Meardon, B.H.; Stewart, R.J.; Williams, W.G.
1978-11-01
Design parameters and performance calculations are given for a straight-slot velocity selector which can be used for discriminating between elastic and inelastic scattering events in small angle scattering experiments on a pulsed neutron source. The selector has a high transmittance over the wavelength range 3 A 5%. (author)
Probing edge-activated resonant Raman scattering from mechanically exfoliated 2D MoO3 nanolayers
International Nuclear Information System (INIS)
Yano, Taka-aki; Yoshida, Keisuke; Hayashi, Tomohiro; Hara, Masahiko; Hayamizu, Yuhei; Ohuchi, Fumio
2015-01-01
We report spatially resolved vibrational analysis of mechanically exfoliated single-crystalline α-MoO 3 nanolayers. Raman scattering from α-MoO 3 was enhanced predominantly at the outside edges of the nanolayers. The enhanced Raman scattering at the edges was attributed primarily to the enhanced resonant Raman effect caused by a high density of oxygen vacancies localized at the edges. The localized vacancy sites corresponded to a non-stoichiometric phase of MoO 3 , which would provide reactive sites with high catalytic activity. (paper)
Energy Technology Data Exchange (ETDEWEB)
Vega C, H. R.; Esparza H, A. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico); Garcia R, M. G. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Zacatecas, Calz. Pedro Coronel 16, Dependencias Federales, 98600 Guadalupe, Zacatecas (Mexico); Reyes R, E. [Universidad de Guanajuato, Campus Leon, Division de Ciencias e Ingenierias, Loma del Bosque 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Hernandez A, L. [Consejo Nacional de Ciencia y Tecnologia, CIBNOR, Mar Bermejo 195, Col. Playa Palo de Santa Rita, 23090 La Paz, Baja California Sur (Mexico); Rivera, T., E-mail: fermineutron@yahoo.com [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Calz. Legaria 694, Col. Irrigacion, 11500 Ciudad de Mexico (Mexico)
2017-10-15
In order to determine the environmental equivalent dose (H(10)), due to the radiation that is dispersed over the body of a patient, 100 thermoluminescent dosimeters (TLD) around 6 MV TomoLINAC were used. The characteristics of the tomotherapy have the disadvantage that the shielding of the bunker increases considerably and for its design validated parameters are used for the conventional Linacs. In order to determine H(10) due to scattered radiation, measurements were made in the vicinity of the isocenter, while the 6 MeV photon beam was applied on a phantom. Also, TLDs were placed on the walls of the bunker that remained for 7 days, where approximately 50 patients were treated per day. At points close to the isocenter, the H(10) has an angular distribution caused by the phantom shape. In the bunker walls the highest H(10) was observed in the primary barriers. In the labyrinth, the impact of the scattered radiation was observed when measuring a greater value of the environmental equivalent dose in the wall furthest from the isocenter compared to the point located closest to it. (Author)
International Nuclear Information System (INIS)
Choi, B.H.; Poe, R.T.
1985-01-01
We present a systematic formulation of the atom--surface scattering dynamics which includes the vibrational states of the atoms in the solid (phonons). The properties of the total scattering wave function of the system, a representation of the interaction potential matrix, and the characteristics of the independent physical solutions are all derived from the translational invariance of the full Hamiltonian. The scattering equations in the integral forms as well as the related Green functions were also obtained. The configurational representations of the Green functions, in particular, are quite different from those of the conventional scattering theory where the collision partners are spatially localized. Various versions of the integral expression of scattering, transition, and reactance matrices were also obtained. They are useful for introducing approximation schemes. From the present formulation, some specific theoretical schemes which are more realistic compared to those that have been employed so far and at the same time capable of yielding effective ab initio computation are derived in the following paper. The time reversal invariance and the microscopic reversibility of the atom--surface scattering were discussed. The relations between the in and outgoing scattering wave functions which are satisfied in the atom--surface system and important in the transition matrix methods were presented. The phonon annihilation and creation, and the adsorption and desorption of the atom are related through the time reversal invariance, and thus the microscopic reversibility can be tested by the experiment
Quantum mechanical study of elastic scattering and rotational excitation of CO by electrons
Onda, K.; Truhlar, D. G.
1980-01-01
Coupling calculations of differential, integral, and momentum transfer cross sections for pure elastic scattering and rotational excitation of CO by electron impact are reported. The calculations are based on a static charge distribution that has correct dipole and quadrupole moments, has cusps at the nuclei, and is augmented by an SCF treatment of charge polarization and a local approximation for exchange. The rotationally summed cross sections, with no adjustable parameters in the scattering calculation, are in reasonably good agreement with the experimental cross sections but are somewhat larger at small scattering angles.
Thermo-mechanical modelling of salt caverns due to fluctuating loading conditions.
Böttcher, N.
2015-12-01
This work summarizes the development and application of a numerical model for the thermo-mechanical behaviour of salt caverns during cyclic gas storage. Artificial salt caverns are used for short term energy storage, such as power-to-gas or compressed air energy storage. Those applications are characterized by highly fluctuating operation pressures due to the unsteady power levels of power plants based on renewable energy. Compression and expansion of the storage gases during loading and unloading stages lead to rapidly changing temperatures in the host rock of the caverns. This affects the material behaviour of the host rock within a zone that extends several meters into the rock mass adjacent to the cavern wall, and induces thermo-mechanical stresses and alters the creep response.The proposed model features the thermodynamic behaviour of the storage medium, conductive heat transport in the host rock, as well as temperature dependent material properties of rock salt using different thermo-viscoplastic material models. The utilized constitutive models are well known and state-of-the-art in various salt mechanics applications. The model has been implemented into the open-source software platform OpenGeoSys. Thermal and mechanical processes are solved using a finite element approach, coupled via a staggered coupling scheme. The simulation results allow the conclusion, that the cavern convergence rate (and thus the efficiency of the cavern) is highly influenced by the loading cycle frequency and the resulting gas temperatures. The model therefore allows to analyse the influence of operation modes on the cavern host rock or on neighbouring facilities.
Mechanisms of northeastern Brazil rainfall anomalies due to Southern Tropical Atlantic variability
Neelin, J.; Su, H.
2004-05-01
Observational studies have shown that the rainfall anomalies in eastern equatorial South America, including Nordeste Brazil, have a positive correlation with tropical southern Atlantic sea surface temperature (SST) anomalies. Such relationships are reproduced in model simulations with the quasi-equilibrium tropical circulation model (QTCM), which includes a simple land model. A suite of model ensemble experiments is analysed using observed SST over the tropical oceans, the tropical Atlantic and the tropical southern Atlantic (30S-0), respectively (with climatological SST in the remainder of the oceans). Warm tropical south Atlantic SST anomalies yield positive precipitation anomalies over the Nordeste and the southern edge of the Atlantic marine intertropical convergence zone (ITCZ). Mechanisms associated with moisture variations are responsible for the land precipitation changes. Increases in moisture over the Atlantic cause positive anomalies in moisture advection, spreading increased moisture downwind. Where the basic state is far from the convective stability threshold, moisture changes have little effect, but the margins of the climatological convection zone are affected. The increased moisture supply due to advection is enhanced by increases in low-level convergence required by moist static energy balances. The moisture convergence term is several times larger, but experiments altering the moisture advection confirm that the feedback is initiated by wind acting on moisture gradient. This mechanism has several features in common with the recently published "upped-ante" mechanism for El Nino impacts on this region. In that case, the moisture gradient is initiated by warm free tropospheric temperature anomalies increasing the typical value of low-level moisture required to sustain convection in the convection zones. Both mechanisms suggest the usefulness of coordinating ocean and land in situ observations of boundary layer moisture.
Key scattering mechanisms limiting the lateral transport in a modulation-doped polar heterojunction
Energy Technology Data Exchange (ETDEWEB)
Tien, Nguyen Thanh, E-mail: nttien@ctu.edu.vn; Thao, Pham Thi Bich [College of Natural Sciences, Can Tho University, 3-2 Road, Can Tho City (Viet Nam); Thao, Dinh Nhu [Center for Theoretical and Computational Physics, College of Education, Hue University, 34 Le Loi Street, Hue City (Viet Nam); Quang, Doan Nhat [Institute of Physics, Vietnamese Academy of Science and Technology, 10 Dao Tan Street, Hanoi (Viet Nam)
2016-06-07
We present a study of the lateral transport of a two-dimensional electron gas (2DEG) in a modulation-doped polar heterojunction (HJ). In contrast to previous studies, we assume that the Coulomb correlation among ionized impurities and among charged dislocations in the HJ is so strong that the 2DEG low-temperature mobility is not limited by impurity and dislocation scattering. The mobility, however, is specified by alloy disorder scattering and combined roughness scattering, which is the total effect induced by both the potential barrier and polarization roughness. The obtained results show that the alloy disorder and combined roughness scattering strongly depend on the alloy content and on the near-interface electron distribution. Our theory is capable of explaining the bell-shaped dependence of the lateral mobility on alloy content observed in AlGaN/GaN and on 2DEG density observed in AlN/GaN, which have not previously been explained.
Schwarz, Massimiliano; Cohen, Denis
2016-04-01
Rainfall is one of the major triggering factor of shallow landslide around the world. The increase of soil moisture in the soil influences the stability of a slope through the increase of soil bulk density, the reduction of soil apparent cohesion (due to suction stress), and the increase in pore water pressure.The spatio-temporal transformations of such properties of soil are know to be heterogeneous and under constant change. For instance, there may be a condition where, in cracked clay-soil, water, during a rain event, produces a rapid increase of pore water pressure along preferential flow-paths (crack or roots), while soil moisture and suction within the soil matrix change minimally. An another site in a sandy soil, the situation might be very different where the increase of soil moisture and pore water pressure, and the decrease of soil suction take place more or less simultaneously across the entire soil profile. In both of these cases topography plays a major role in determining the accumulation of water along the slope through different subsurface flows intensities and directions. In many documented cases in the Alps, shallow landslides may also be triggered by the punctual exfiltration of water from bedrock or weathered geological strata. The hydro-geological characteristics of the catchment control this mechanism. These different situations aim to give an idea of the large spectrum of hydrological triggering conditions of shallow landslides. The heterogeneities of these hydrological conditions represent a difficult issue in modeling shallow landslide triggering mechanisms. In the simplest models, hydrology is assumed to influence changes in pore water pressure only, mostly using one dimensional vertical infiltration models. More advanced models consider changes in apparent cohesion due to changes in soil moisture or include more complex hydrological models to simulate water flow and distribution during a rainfall event. However, most models at the
International Nuclear Information System (INIS)
Hategan, Cornel; Comisel, Horia; Ionescu, Remus A.
2004-01-01
The quasiresonant scattering consists from a single channel resonance coupled by direct interaction transitions to some competing reaction channels. A description of quasiresonant Scattering, in terms of generalized reduced K-, R- and S- Matrix, is developed in this work. The quasiresonance's decay width is, due to channels coupling, smaller than the width of the ancestral single channel resonance (resonance's direct compression). (author)
Mechanical effects associated with surface loading of dry rock due to glaciation
International Nuclear Information System (INIS)
Wahi, K.K.; Hunter, R.L.
1985-01-01
Many scenarios of interest for a repository in the Pasco Basin begin with glaciation. Loading and unloading of joints and fractures due to the weight of ice sheets could affect the hydrologic properties of the host rock and surrounding units. Scoping calculations performed using two-dimensional numerical models with simplifying assumptions predict stress changes and uplift or subsidence caused by an advancing glacier. The magnitudes of surface uplift and subsidence predicted by the study agree well with previous independent predictions. Peak stress unloading near the repository horizon is a small fraction of the ambient stress. Any resultant aperture increase is likewise small. Based on the results of this study, mechanical loading caused by a glacier is expected to have a minimal effect on rock permeability, assuming that the excess compressive loads do not crush the rock. 13 refs., 3 figs., 1 tab
Palm, Andreas; Midgren, Bengt; Janson, Christer; Lindberg, Eva
2016-01-01
Obesity hypoventilation syndrome (OHS) is often diagnosed late. The aim of this study was to analyse gender differences at initiation of long-term mechanical ventilation (LTMV) in patients with (OHS), to analyse gender differences in treatment effect and to study how the prescription of LTMV due to OHS has changed over time. Data on patients on LTMV due to OHS between 1996 and 2014 were obtained from Swedevox, a nationwide health quality registry of patients on LTMV in Sweden. When starting LTMV, women were generally older (age 64.4 ± 11.2 vs. 60.1 ± 12.1 years, p obese (BMI 43.0 ± 8.2 vs. 41.5 ± 7.9 kg/m2, p differ. During the study period, the age of patients at the initiation of LTMV rose by 3.4 years/decade (P = 0.001) in women and with 1.9 years/decade (P = 0.048) in men but there were no significant changes in BMI (P = 0.425). Diagnosis of OHS is more delayed in women and as a consequence the disease is more advanced when diagnosed. In spite of this, there is no gender difference in survival rate in patients with OHS treated with LTMV. More and older patients with OHS nowadays gain access to LTMV. Copyright © 2015 Elsevier Ltd. All rights reserved.
Conduction mechanism of leakage current due to the traps in ZrO2 thin film
International Nuclear Information System (INIS)
Seo, Yohan; Lee, Sangyouk; An, Ilsin; Jeong, Heejun; Song, Chulgi
2009-01-01
In this work, a metal-oxide-semiconductor capacitor with zirconium oxide (ZrO 2 ) gate dielectric was fabricated by an atomic layer deposition (ALD) technique and the leakage current characteristics under negative bias were studied. From the result of current–voltage curves there are two possible conduction mechanisms to explain the leakage current in the ZrO 2 thin film. The dominant mechanism is the space charge limited conduction in the high-electric field region (1.5–5.0 MV cm −1 ) while the trap-assisted tunneling due to the existence of traps is prevailed in the low-electric field region (0.8–1.5 MV cm −1 ). Conduction caused by the trap-assisted tunneling is found from the experimental results of a weak temperature dependence of current, and the trap barrier height is obtained. The space charge limited conduction is evidenced, for different temperatures, by Child's law dependence of current density versus voltage. Child's law dependence can be explained by considering a single discrete trapping level and we can obtain the activation energy of 0.22 eV
Conduction mechanism of leakage current due to the traps in ZrO2 thin film
Seo, Yohan; Lee, Sangyouk; An, Ilsin; Song, Chulgi; Jeong, Heejun
2009-11-01
In this work, a metal-oxide-semiconductor capacitor with zirconium oxide (ZrO2) gate dielectric was fabricated by an atomic layer deposition (ALD) technique and the leakage current characteristics under negative bias were studied. From the result of current-voltage curves there are two possible conduction mechanisms to explain the leakage current in the ZrO2 thin film. The dominant mechanism is the space charge limited conduction in the high-electric field region (1.5-5.0 MV cm-1) while the trap-assisted tunneling due to the existence of traps is prevailed in the low-electric field region (0.8-1.5 MV cm-1). Conduction caused by the trap-assisted tunneling is found from the experimental results of a weak temperature dependence of current, and the trap barrier height is obtained. The space charge limited conduction is evidenced, for different temperatures, by Child's law dependence of current density versus voltage. Child's law dependence can be explained by considering a single discrete trapping level and we can obtain the activation energy of 0.22 eV.
Mechanical Properties and Elastic Constants Due to Damage Accumulation and Amorphization in SiC
International Nuclear Information System (INIS)
Gao, Fei; Weber, William J.
2004-01-01
Damage accumulation due to cascade overlap, which was simulated previously, has been used to study the changes of elastic constants, bulk and elastic moduli as a function of dose. These mechanical properties generally decrease with increasing dose, and the rapid decrease at low-dose level indicates that point defects and small clusters play an important role in the changes of elastic constants rather than topological disorder. The internal strain relaxation has no effect on the elastic constants, C11 and C12, in perfect SiC, but it has a significant influence on all elastic constants calculated in damaged SiC. The elastic constants in the cascade-amorphized (CA) SiC decrease about 19%, 29% and 46% for C11, C12 and C44, respectively. The bulk modulus decrease 23% and the elastic modulus decreases 29%, which is consistent with experimental measurements. The stability of both the perfect SiC and CA-SiC under hydrostatic tension has been also investigated. All mechanical properties in the CA-SiC exhibit behavior similar to that in perfect SiC, but the critical stress at which the CA-SiC becomes structurally unstable is one order of magnitude smaller than that for perfect SiC
International Nuclear Information System (INIS)
Bao Xiaoyi; Zhang Chunshu; Li Wenhai; Eisa, M; El-Gamal, S; Benmokrane, B
2008-01-01
For the first time to our knowledge, distributed impact waves due to the highway traffic on concrete slabs reinforced with FRP bars are monitored in real time using stimulated Brillouin scattering. The impact wave is caused by the traffic passing on the highway pavement at high speed (>100 km h −1 ), which induced pressure on the concrete slabs, and in turn created a local birefringence change, leading to variation of the local state of polarization change (SOP). The pump and probe waves of the stimulated Brillouin scattering 'see' the SOP change and react with a decrease of the Brillouin gain or loss signal, when the pump and probe waves have the same input polarization state. The frequency difference between the pump and probe waves are locked at the static-strain-related Brillouin frequency. Optical fiber was embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montréal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz. A spatial resolution of 2 m was used over a sensing length of 300 m
Karlsson, Maths
2015-01-07
This article is concerned with the use of quasielastic neutron scattering as a technique for investigation of the dynamical properties of proton conducting oxides. Currently, the main interest in these materials comes from their promise as electrolytes in future electrochemical devices and particularly through their use as electrolytes in next-generation, intermediate-temperature, fuel cells. However, the realization of such devices depends critically on the development of new, more highly proton conducting oxides. Such a development depends on increasing the current understanding of proton conduction in oxides and for this purpose quasielastic neutron scattering is an important mean. The aim of this article is to introduce the non-specialist reader to the basic principles of quasielastic neutron scattering, its advantages and disadvantages, to summarize the work that has been done on proton conducting oxides using this technique, as well as to discuss future opportunities within this field of research.
International Nuclear Information System (INIS)
Matsuura, Hideaki; Sugiyama, Shota; Kajimoto, Shogo; Sawada, Daisuke; Nishimura, Yosuke; Kawamoto, Yasuko
2016-01-01
A knock-on tail formation in deuteron velocity distribution function due to nuclear elastic scattering (NES) by energetic protons and its observation method using γ-ray-generating "6Li(d,pγ)"7Li reaction are examined for proton-beam-injected deuterium plasmas. The proton velocity distribution function is obtained by means of the ion trajectory analysis in a Tokamak magnetic configuration. The knock-on tail in two-dimensional (2D) deuteron velocity distribution function due to NES by energetic protons is evaluated via Boltzmann collision integral and 2D Fokker-Planck simulation. From the 2D deuteron velocity distribution function obtained, enhancement of the emission rate of 0.48-MeV γ-rays by "6Li(d,p)"7Li*, "7Li*→"7Li+γ reaction due to NES is evaluated. It is shown that the γ-ray emission rate is significantly influenced by the magnitude of the knock-on tail, and the γ-ray-generating reaction can be a useful tool for the knock-on tail observation. (author)
Consideration on the Mechanism of Microwave Emission Due to Rock Fracture
Takano, Tadashi; Sugita, Seiji; Yoshida, Shingo; Maeda, Takashi
2010-05-01
Microwave emission due to rock fracture was found at 300 MHz, 2 GHz, and 22 GHz, and its power was calibrated in laboratory for the first time in the world. The observed waveform is impulsive, and contains correspondent frequency component inside the envelope at each frequency band. At such high frequencies, the electro-magnetic signal power can be calibrated as a radiating wave with high accuracy. Accordingly, it was verified that a substantial power is emitted. The microwave emission phenomena were also observed on occasions of hypervelocity impact, and esteemed as phenomena generally associated with material destruction. Earthquakes and volcanic activities are association with rock fractures so that the microwave is expected to be emitted. Actually, the e emission was confirmed by the data analysis of the brightness temperature obtained by a remote sensing satellite, which flew over great earthquakes of Wuenchan and Sumatra, and great volcanic eruptions of Reventador and Chanten. It is important to show the microwave emission during rock fracture in natural phenomena. Therefore, the field test to detect the microwave due to the collapse of a crater cliff was planned and persecuted at the volcano of Miyake-jima about 100 km south of Tokyo. Volcanic activity may be more convenient than an earthquake because of the known location and time. As a result, they observed the microwave emission which was strongly correlated with the cliff collapses. Despite of the above-mentioned phenomenological fruits, the reason of the microwave emission is not fixed yet. We have investigated the mechanism of the emission in consideration of the obtained data in rock fracture experiments so far and the study results on material destruction by hypervelocity impact. This paper presents the proposal of the hypothesis and resultant discussions. The microwave sensors may be useful to monitor natural hazards such as an earthquake or a volcanic eruption, because the microwave due to rock
Alteration of dentin-enamel mechanical properties due to dental whitening treatments.
Zimmerman, B; Datko, L; Cupelli, M; Alapati, S; Dean, D; Kennedy, M
2010-05-01
The mechanical properties of dentin and enamel affect the reliability and wear properties of a tooth. This study investigated the influence of clinical dental treatments and procedures, such as whitening treatments or etching prior to restorative procedures. Both autoclaved and non-autoclaved teeth were studied in order to allow for both comparison with published values and improved clinical relevance. Nanoindentation analysis with the Oliver-Pharr model provided elastic modulus and hardness across the dentin-enamel junction (DEJ). Large increases were observed in the elastic modulus of enamel in teeth that had been autoclaved (52.0 GPa versus 113.4 GPa), while smaller increases were observed in the dentin (17.9 GPa versus 27.9 GPa). Likewise, there was an increase in the hardness of enamel (2.0 GPa versus 4.3 GPa) and dentin (0.5 GPa versus 0.7 GPa) with autoclaving. These changes suggested that the range of elastic modulus and hardness values previously reported in the literature may be partially due to the sterilization procedures. Treatment of the exterior of non-autoclaved teeth with Crest Whitestrips, Opalescence or UltraEtch caused changes in the mechanical properties of both the enamel and dentin. Those treated with Crest Whitestrips showed a reduction in the elastic modulus of enamel (55.3 GPa to 32.7 GPa) and increase in the elastic modulus of dentin (17.2 GPa to 24.3 GPa). Opalescence treatments did not significantly affect the enamel properties, but did result in a decrease in the modulus of dentin (18.5 GPa to 15.1 GPa). Additionally, as expected, UltraEtch treatment decreased the modulus and hardness of enamel (48.7 GPa to 38.0 GPa and 1.9 GPa to 1.5 GPa, respectively) and dentin (21.4 GPa to 15.0 GPa and 1.9 GPa to 1.5 GPa, respectively). Changes in the mechanical properties were linked to altered protein concentration within the tooth, as evidenced by fluorescence microscopy and Fourier transform infrared spectroscopy. Published by Elsevier Ltd.
Inelastic scattering of {sup 9}Li and excitation mechanism of its first excited state
Energy Technology Data Exchange (ETDEWEB)
Al Falou, H. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Kanungo, R., E-mail: ritu@triumf.ca [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Andreoiu, C.; Cross, D.S. [Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Davids, B.; Djongolov, M. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Gallant, A.T. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of British Columbia, British Columbia V6T 1Z4 (Canada); Galinski, N.; Howell, D. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Kshetri, R.; Niamir, D. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Orce, J.N. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of the Western Cape, P/B X17, Bellville, ZA-7535 (South Africa); Shotter, A.C. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Sjue, S. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Tanihata, I. [Research Center for Nuclear Physics, Osaka University, Mihogaoka, Ibaraki, Osaka 567 0047 (Japan); Thompson, I.J. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Triambak, S. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Uchida, M. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Walden, P. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Wiringa, R.B. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)
2013-04-25
The first measurement of inelastic scattering of {sup 9}Li from deuterons at the ISAC facility is reported. The measured angular distribution for the first excited state confirms the nature of excitation to be an E2 transition. The quadrupole deformation parameter is extracted from an analysis of the angular distribution.
Inelastic scattering of 9Li and excitation mechanism of its first excited state
International Nuclear Information System (INIS)
Al Falou, H.; Kanungo, R.; Andreoiu, C.; Cross, D.S.; Davids, B.; Djongolov, M.; Gallant, A.T.; Galinski, N.; Howell, D.; Kshetri, R.; Niamir, D.; Orce, J.N.; Shotter, A.C.; Sjue, S.; Tanihata, I.; Thompson, I.J.; Triambak, S.; Uchida, M.; Walden, P.; Wiringa, R.B.
2013-01-01
The first measurement of inelastic scattering of 9 Li from deuterons at the ISAC facility is reported. The measured angular distribution for the first excited state confirms the nature of excitation to be an E2 transition. The quadrupole deformation parameter is extracted from an analysis of the angular distribution
International Nuclear Information System (INIS)
Heil, T.G.
1984-01-01
The research done under this contract should provide valuable contributions to our understanding of atomic collision processes. The essence of this project is the description of low energy atomic collision process using molecular states formed by the collision partners in the interaction region. Over the eight months that this contract has been in effect, significant progress has been made on both fundamental and applied levels. On the most basic level, we have recently developed a new diabatic representation of the scattering which has none of the defects associated with the most commonly used formulation of Smith. This may prove to be of great importance since a proper diabatic description is thought to be a more reasonable representation of the actual physical scattering process than the adiabatic description. It should be noted that there is a great deal of controversy surrounding the word proper but our new formulation satisfies most, if not all, criteria for diabatic states. In addition, we have carried out or initiated theoretical studies on a number of atomic scattering processes involving charge transfer reactions and proton-induced fine-structure transitions. Our calculations of differential scattering cross sections for low energy charge transfer reaction should be of particular importance. A number of experimental groups are now proposing to measure these cross sections which our calculations predict should have large, striking features. Such comparisons would provide valuable tests of the theory of low energy atomic collision processes on a more fundamental level than previous comparisons of the total cross sections
Scaling of heat transfer augmentation due to mechanical distortions in hypervelocity boundary layers
Flaherty, W.; Austin, J. M.
2013-10-01
We examine the response of hypervelocity boundary layers to global mechanical distortions due to concave surface curvature. Surface heat transfer and visual boundary layer thickness data are obtained for a suite of models with different concave surface geometries. Results are compared to predictions using existing approximate methods. Near the leading edge, good agreement is observed, but at larger pressure gradients, predictions diverge significantly from the experimental data. Up to a factor of five underprediction is reported in regions with greatest distortion. Curve fits to the experimental data are compared with surface equations. We demonstrate that reasonable estimates of the laminar heat flux augmentation may be obtained as a function of the local turning angle for all model geometries, even at the conditions of greatest distortion. This scaling may be explained by the application of Lees similarity. As a means of introducing additional local distortions, vortex generators are used to impose streamwise structures into the boundary layer. The response of the large scale vortices to an adverse pressure gradient is investigated. Surface streak evolution is visualized over the different surface geometries using fast response pressure sensitive paint. For a flat plate baseline case, heat transfer augmentation at similar levels to turbulent flow is measured. For the concave geometries, increases in heat transfer by factors up to 2.6 are measured over the laminar values. The scaling of heat transfer with turning angle that is identified for the laminar boundary layer response is found to be robust even in the presence of the imposed vortex structures.
Mechanism of Cuticle Hole Development in Human Hair Due to UV-Radiation Exposure
Directory of Open Access Journals (Sweden)
Kazuhisa Maeda
2018-03-01
Full Text Available Hair is easily damaged by ultraviolet (UV radiation, bleaching agents or permanent wave treatments, and as damage progresses, hair loses its gloss, develops split ends and breaks. However, the causes of hair damage due to UV radiation have not yet been clarified. We discovered that in one mechanism facilitating damage to wet hair by UV radiation, the unsaturated fatty acids in wet hair produce hydroxy radicals upon exposure to UV radiation, and these radicals produce cuticle holes between the cuticle layers. In wet hair exposed to UV radiation, cuticle holes were produced only between the cuticle layers, whereas when human hair was immersed in a solution containing hydroxy radicals produced by Fenton’s reaction, a random production of cuticle holes was noted. It is thought that hydroxy radicals are produced only between the cuticle layers by exposure to UV radiation, and cuticle holes are formed only in this region because one of the polyunsaturated fatty acids, linoleic acid, with a bis-allyl hydrogen, is found between the cuticle layers.
Directory of Open Access Journals (Sweden)
S. Ghods
2015-12-01
Full Text Available Cloude–Pottier entropy and α-angle are two important parameters for the interpretation of fully polarimetric data. They indicate the randomness of the polarisation of the back scattered waves and the scattering mechanisms of the targets respectively. For fully polarimetric data the H-α plane is presented which using the borders of it the full polarimetric data can be classified into 8 different physical scattering mechanisms. In recent years new approaches have proposed H-α classification spaces by mapping the points which are belong to each PSMs of FP data into the space of H/α for CP data and approximate borders were extracted for the classification purpose. In this paper a novel approach for defining H/α classification plane has been presented which maximizes the producer’s accuracy. The optimum borders have been found and the results of classification using the new plane have been compared with the rival method and the superiority of the new proposed method has been revealed.
International Nuclear Information System (INIS)
Stuchlik, Zdenek; Kolos, Martin
2016-01-01
To test the role of large-scale magnetic fields in accretion processes, we study the dynamics of the charged test particles in the vicinity of a black hole immersed into an asymptotically uniform magnetic field. Using the Hamiltonian formalism of the charged particle dynamics, we examine chaotic scattering in the effective potential related to the black hole gravitational field combined with the uniform magnetic field. Energy interchange between the translational and oscillatory modes of the charged particle dynamics provides a mechanism for charged particle acceleration along the magnetic field lines. This energy transmutation is an attribute of the chaotic charged particle dynamics in the combined gravitational and magnetic fields only, the black hole rotation is not necessary for such charged particle acceleration. The chaotic scatter can cause a transition to the motion along the magnetic field lines with small radius of the Larmor motion or vanishing Larmor radius, when the speed of the particle translational motion is largest and it can be ultra-relativistic. We discuss the consequences of the model of ionization of test particles forming a neutral accretion disc, or heavy ions following off-equatorial circular orbits, and we explore the fate of heavy charged test particles after ionization where no kick of heavy ions is assumed and only the switch-on effect of the magnetic field is relevant. We demonstrate that acceleration and escape of the ionized particles can be efficient along the Kerr black hole symmetry axis parallel to the magnetic field lines. We show that a strong acceleration of the ionized particles to ultra-relativistic velocities is preferred in the direction close to the magnetic field lines. Therefore, the process of ionization of Keplerian discs around the Kerr black holes can serve as a model of relativistic jets. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Stuchlik, Zdenek; Kolos, Martin [Silesian University in Opava, Faculty of Philosophy and Science, Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Opava (Czech Republic)
2016-01-15
To test the role of large-scale magnetic fields in accretion processes, we study the dynamics of the charged test particles in the vicinity of a black hole immersed into an asymptotically uniform magnetic field. Using the Hamiltonian formalism of the charged particle dynamics, we examine chaotic scattering in the effective potential related to the black hole gravitational field combined with the uniform magnetic field. Energy interchange between the translational and oscillatory modes of the charged particle dynamics provides a mechanism for charged particle acceleration along the magnetic field lines. This energy transmutation is an attribute of the chaotic charged particle dynamics in the combined gravitational and magnetic fields only, the black hole rotation is not necessary for such charged particle acceleration. The chaotic scatter can cause a transition to the motion along the magnetic field lines with small radius of the Larmor motion or vanishing Larmor radius, when the speed of the particle translational motion is largest and it can be ultra-relativistic. We discuss the consequences of the model of ionization of test particles forming a neutral accretion disc, or heavy ions following off-equatorial circular orbits, and we explore the fate of heavy charged test particles after ionization where no kick of heavy ions is assumed and only the switch-on effect of the magnetic field is relevant. We demonstrate that acceleration and escape of the ionized particles can be efficient along the Kerr black hole symmetry axis parallel to the magnetic field lines. We show that a strong acceleration of the ionized particles to ultra-relativistic velocities is preferred in the direction close to the magnetic field lines. Therefore, the process of ionization of Keplerian discs around the Kerr black holes can serve as a model of relativistic jets. (orig.)
International Nuclear Information System (INIS)
Bertagnolli, H.
1978-01-01
For the case of special molecular models representing the acetonitrile molecule the expansion coefficients of the molecular par distribution function are calculated by use of pertubation theory. These results are used to get theoretical access to scattering intensities in the frame of several approximations. The first model describes the molecule by three hard spheres and uses a hard sphere liquid as reference. In the second cast the calculations are based on an anisotropic Lennard-Jones potential by application of a model of overlapping ellipsoids and by use of a Lennard-Jones liquid as a reference system. In the third model dipolar attractive forces are taken into account with an anisotropic hard-sphere liquid as a reference. In the third model dipolar attractive forces are taken into account with an anisotropic hard-sphere liquid as a reference. Finally all the calculations with different intermolecular potentials are compared with neutron scattering experiments. (orig.) 891 HK [de
Malhotra, A.; Mathews, J. D.
2011-01-01
There has been much interest in the meteor physics community recently regarding the form that meteoroid mass flux arrives in the upper atmosphere. Of particular interest are the relative roles of simple ablation, differential ablation, and fragmentation in the meteoroid mass flux observed by the Incoherent Scatter Radars (ISR). We present here the first-ever statistical study showing the relative contribution of the above-mentioned three mechanisms. These are also one of the first meteor results from the newly-operational Resolute Bay ISR. These initial results emphasize that meteoroid disintegration into the upper atmosphere is a complex process in which all the three above-mentioned mechanisms play an important role though fragmentation seems to be the dominant mechanism. These results prove vital in studying how meteoroid mass is deposited in the upper atmosphere which has important implications to the aeronomy of the region and will also contribute in improving current meteoroid disintegration/ablation models.
Shu, Deming; Shvydko, Yuri; Stoupin, Stanislav A.; Khachatryan, Ruben; Goetze, Kurt A.; Roberts, Timothy
2015-04-14
A method and an ultrahigh-resolution spectrometer including a precision mechanical structure for positioning inelastic X-ray scattering optics are provided. The spectrometer includes an X-ray monochromator and an X-ray analyzer, each including X-ray optics of a collimating (C) crystal, a pair of dispersing (D) element crystals, anomalous transmission filter (F) and a wavelength (W) selector crystal. A respective precision mechanical structure is provided with the X-ray monochromator and the X-ray analyzer. The precision mechanical structure includes a base plate, such as an aluminum base plate; positioning stages for D-crystal alignment; positioning stages with an incline sensor for C/F/W-crystal alignment, and the positioning stages including flexure-based high-stiffness structure.
International Nuclear Information System (INIS)
Schumacher, Jan W.
2010-10-01
An analysis of the expected sensitivity of the ATLAS experiment at the Large Hadron Collider at CERN to alternative mechanisms of electroweak symmetry breaking in the dileptonic vector boson scattering channel is presented. With the generalized K-Matrix model of vector boson scattering recently implemented in the event generator Whizard, several additional resonances are investigated. Whizard is validated for ATLAS use and an interface for the Les Houches event format is adapted for the ATLAS software Athena. Systematic model and statistical Monte Carlo uncertainties are reduced with a signal definition using events reweighted in the couplings g of the new resonances. Angular correlations conserved by Whizard are used in the event selection. A multivariate analyzer is trained to take into account correlations between the selection variables and thereby to improve the sensitivity compared to cut analyses. The statistical analysis is implemented with a profile likelihood method taking into account systematic uncertainties and statistical uncertainties from Monte Carlo. Ensemble tests are performed to assure the applicability of the method. Expected discovery significances and coupling limits for new additional resonances in vector boson scattering are determined. (orig.)
Biswas, Nandita; Thomas, Susy; Sarkar, Anjana; Mukherjee, Tulsi; Kapoor, Sudhir
2009-09-01
Surface-enhanced Raman scattering (SERS) of thiamazole have been investigated in aqueous solution. Thiamazole is an important anti-thyroid drug that is used in the treatment of hyperthyroidism (over activity of the thyroid gland). Due to its medicinal importance, the surface adsorption properties of thiamazole have been studied. The experimental Raman and SERS data are supported with DFT calculations using B3LYP functional with LANL2DZ basis set. From the SERS spectra as well as theoretical calculations, it has been inferred that thiamazole is chemisorbed to the silver surface directly through the sulphur atom and the ring N atom, with a tilted orientation.
International Nuclear Information System (INIS)
Ruscak, M.; Zamboch, M.
1998-01-01
Reactor internals are subject to three principle operation influences: neutron and gamma irradiation, mechanical stresses, both static and dynamic, and coolant chemistry. Several cases of damage have been reported in previous years in both boiling and pressure water reactors. They are linked with the term of irradiation assisted stress corrosion cracking as a possible damage mechanism. In WWERs, the principal material used for reactor internals is austenitic titanium stabilized stainless steel 08Kh18N10T, however high strength steels are used as well. To assess the changes of mechanical properties and to determine whether sensitivity to intergranular cracking can be increased by high neutron fluences, the experimental program has been started. The goal is to assure safe operation of the internals as well as life management for all planned operation period. The program consists of tests of material properties, both mechanical and corrosion-mechanical. Detailed neutron fluxes calculation as well as stress and deformation calculations are part of the assessment. Model of change will be proposed in order to plan inspections of the facility. In situ measurements of internals will be used to monitor exact status of structure during operation. Tensile specimens manufactured from both base metal and model weld joint have been irradiated to the total fluences of 3-20 dpa. Changes of mechanical properties are tested by the tensile test, stress corrosion cracking tests are performed in the autoclave with water loop and active loading. Operation temperature, pressure and water chemistry are chosen for the tests. (author)
Joo, Min-Kyu; Moon, Byoung Hee; Ji, Hyunjin; Han, Gang Hee; Kim, Hyun; Lee, Gwanmu; Lim, Seong Chu; Suh, Dongseok; Lee, Young Hee
2017-02-08
As the thickness becomes thinner, the importance of Coulomb scattering in two-dimensional layered materials increases because of the close proximity between channel and interfacial layer and the reduced screening effects. The Coulomb scattering in the channel is usually obscured mainly by the Schottky barrier at the contact in the noise measurements. Here, we report low-temperature (T) noise measurements to understand the Coulomb scattering mechanism in the MoS 2 channel in the presence of h-BN buffer layer on the silicon dioxide (SiO 2 ) insulating layer. One essential measure in the noise analysis is the Coulomb scattering parameter (α SC ) which is different for channel materials and electron excess doping concentrations. This was extracted exclusively from a 4-probe method by eliminating the Schottky contact effect. We found that the presence of h-BN on SiO 2 provides the suppression of α SC twice, the reduction of interfacial traps density by 100 times, and the lowered Schottky barrier noise by 50 times compared to those on SiO 2 at T = 25 K. These improvements enable us to successfully identify the main noise source in the channel, which is the trapping-detrapping process at gate dielectrics rather than the charged impurities localized at the channel, as confirmed by fitting the noise features to the carrier number and correlated mobility fluctuation model. Further, the reduction in contact noise at low temperature in our system is attributed to inhomogeneous distributed Schottky barrier height distribution in the metal-MoS 2 contact region.
On the mechanism of spin-dependent (e,2e) scattering from a ferromagnetic surface
International Nuclear Information System (INIS)
Samarin, S N; Sergeant, A D; Pravica, L; Cvejanovic, D; Wilkie, P; Guagliardo, P; Williams, J F; Artamonov, O M; Suvorova, A A
2009-01-01
A simple model is suggested for a qualitative analysis of spin-dependent (e,2e) reaction on a ferromagnetic surface. The model is based on the scattering of the primary electron with the average spin projection 1 > by the valence electron with the average spin projection 2 >. To test the model the energy distributions of correlated electron pairs are measured for parallel and anti-parallel orientations of the magnetic moment of the cobalt film and polarization vector of the incident beam. The proposed model explains qualitatively the spin-asymmetry of the measured binding energy spectrum.
Mechanism design of the Thomson scattering diagnostic system for the TMX east mirror plug
International Nuclear Information System (INIS)
Lang, D.D.; Goodman, R.K.; Jenkins, S.L.; Wilkerson, J.A.; Parkinson, J.L.
1979-01-01
This Thomson scattering diagnostic system is used to measure the electron temperature and density of the east mirror plug of the Tandem Mirror Experiment (TMX) at Lawrence Livermore Laboratory. The measurements are made by firing a high-power ruby laser pulse through the plasma where the electrons then re-radiate a small fraction of the light. Because of the velocity of the electrons, the wavelength of the re-radiated light is Doppler shifted. The width of the Doppler-shifted wavelength spectrum is a measure of the temperature of the electrons in the plasma, and the total amount of re-radiated light is proportional to the electron density
International Nuclear Information System (INIS)
Bardel, Didier; Perez, Michel; Nelias, Daniel; Chaise, Thibaut; Garnier, Jerome; Bourlier, Florent
2014-01-01
The aim of this research is to link the microstructural state and the mechanical properties of an age hardening alloy during a fast heat treatment such as encountered during welding. A coupled model between precipitation state and mechanical properties is used to predict the yield strength and hardening behavior that can be observed experimentally. The method permits the identification of the kinematic and isotropic contributions in the hardening model. The methodology is applied to a 6061-T6 aluminium alloy which is used in the Jules Horowitz reactor vessel. The general idea of this methodology is to couple an efficient microstructural model to a mechanical one based on the dislocation theory and ad'hoc experiments. The theoretical background is based on the work of Kampmann and Wagner, known as the KWN model, to account for nucleation, growth/dissolution and coarsening of precipitates. This analysis requires transient thermo-mechanical experimental data. The efficiency of these models and their coupling are shown for a series 6XXX aluminium alloy which contains β'' and β' precipitates. Ultimately these models are coupled to a FEA model and allows to predict the distribution of precipitates within each element of the mesh, and subsequently its mechanical behavior. (authors)
Leyland, M J; Beurskens, M N A; Flanagan, J C; Frassinetti, L; Gibson, K J; Kempenaars, M; Maslov, M; Scannell, R
2016-01-01
The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.
Mechanical Kerr nonlinearities due to bipolar optical forces between deformable silicon waveguides.
Ma, Jing; Povinelli, Michelle L
2011-05-23
We use an analytical method based on the perturbation of effective index at fixed frequency to calculate optical forces between silicon waveguides. We use the method to investigate the mechanical Kerr effect in a coupled-waveguide system with bipolar forces. We find that a positive mechanical Kerr coefficient results from either an attractive or repulsive force. An enhanced mechanical Kerr coefficient several orders of magnitude larger than the intrinsic Kerr coefficient is obtained in waveguides for which the optical mode approaches the air light line, given appropriate design of the waveguide dimensions.
Three-dimensional quantum mechanical studies of D+H2 → HD+H reactive scattering
International Nuclear Information System (INIS)
Tang, K.T.; Choi, B.H.
1975-01-01
A three-dimensional quantum mechanical study is made on the reactive scattering of D+H 2 → DH+H. The differential and total cross sections as well as the S-matrix elements are obtained from the adiabatic distorted wave model. With the initial molecule H 2 in the ground rotational state, we calculated the cross sections for reactions to all possible rotational states of the product molecule DH. The potential used is that of the Porter and Karplus semiempirical surface. The reactive scattering is predominantly backward. However, the peak in the differential cross sections gradually shifts away from theta=π as the energy is increased, with higher rotational states shifting more. In the thermal energy region, there is virtually no scattering in forward directions. The reaction is endothermic but only slightly so. Although the 0→0 rotational transition contributes only a small fraction to the total reactive cross section, most product molecules prefer rotational states that are considerably lower than the highest one allowed by energy conservation. Differential cross sections summed over all possible final rotational states are significantly different from that of any one state. Previous three-dimensional quantum mechanical studies on this system are all limited to one final rotational state; these previous results are compared with the result of the corresponding case in the present study. The present results are also compared with the corresponding classical trajectory calculations on the same potential surface. Finally, the experimental measurements of Geddes, Kraus, and Fite are compared with the present results. Qualitatively, there are general agreements. but quantitatively the calculated cross sections are definitely too large as compared with the experimental ones. The most likely cause for this difference is that the potential surface used is ''too reactive.''
Review of collapse triggering mechanism of collapsible soils due to wetting
Directory of Open Access Journals (Sweden)
Ping Li
2016-04-01
Full Text Available Loess soil deposits are widely distributed in arid and semi-arid regions and constitute about 10% of land area of the world. These soils typically have a loose honeycomb-type meta-stable structure that is susceptible to a large reduction in total volume or collapse upon wetting. Collapse characteristics contribute to various problems to infrastructures that are constructed on loess soils. For this reason, collapse triggering mechanism for loess soils has been of significant interest for researchers and practitioners all over the world. This paper aims at providing a state-of-the-art review on collapse mechanism with special reference to loess soil deposits. The collapse mechanism studies are summarized under three different categories, i.e. traditional approaches, microstructure approach, and soil mechanics-based approaches. The traditional and microstructure approaches for interpreting the collapse behavior are comprehensively summarized and critically reviewed based on the experimental results from the literature. The soil mechanics-based approaches proposed based on the experimental results of both compacted soils and natural loess soils are reviewed highlighting their strengths and limitations for estimating the collapse behavior. Simpler soil mechanics-based approaches with less parameters or parameters that are easy-to-determine from conventional tests are suggested for future research to better understand the collapse behavior of natural loess soils. Such studies would be more valuable for use in conventional geotechnical engineering practice applications.
Zizka, J.; King, S.; Every, A.; Sooryakumar, R.
2018-04-01
To reduce the RC (resistance-capacitance) time delay of interconnects, a key development of the past 20 years has been the introduction of porous low-k dielectrics to replace the traditional use of SiO2. Moreover, in keeping pace with concomitant reduction in technology nodes, these low-k materials have reached thicknesses below 100 nm wherein the porosity becomes a significant fraction of the film volume. The large degree of porosity not only reduces mechanical strength of the dielectric layer but also renders a need for non-destructive approaches to measure the mechanical properties of such ultra-thin films within device configurations. In this study, surface Brillouin scattering (SBS) is utilized to determine the elastic constants, Poisson's ratio, and Young's modulus of these porous low-k SiOC:H films (˜ 25-250 nm thick) grown on Si substrates by probing surface acoustic phonons and their dispersions.
Hybrid theory and calculation of e-N2 scattering. [quantum mechanics - nuclei (nuclear physics)
Chandra, N.; Temkin, A.
1975-01-01
A theory of electron-molecule scattering was developed which was a synthesis of close coupling and adiabatic-nuclei theories. The theory is shown to be a close coupling theory with respect to vibrational degrees of freedom but is a adiabatic-nuclei theory with respect to rotation. It can be applied to any number of partial waves required, and the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations and not on experiment can be given as to which partial waves and energy domains require the various approximations. The theory allows all cross sections (i.e., pure rotational, vibrational, simultaneous vibration-rotation, differential and total) to be calculated. Explicit formulae for all the cross sections are presented.
International Nuclear Information System (INIS)
Miller, W.H.
1989-08-01
It has recently been discovered that the S-matrix version of the Kohn variational principle is free of the ''Kohn anomalies'' that have plagued other versions and prevented its general use. This has made a major contribution to heavy particle reactive (and also to electron-atom/molecule) scattering which involve non-local (i.e., exchange) interactions that prevent solution of the coupled channel equations by propagation methods. This paper reviews the methodology briefly and presents a sample of integral and differential cross sections that have been obtained for the H + H 2 → H 2 +H and D + H 2 → HD + H reactions in the high energy region (up to 1.2 eV translational energy) relevant to resonance structures reported in recent experiments. 35 refs., 11 figs
Structural phase transitions and Huang scattering
International Nuclear Information System (INIS)
Yamada, Yasusada
1980-01-01
The usefulness of the application of the concept of Huang scattering to the understandings of the origin of diffuse scatterings near structural phase transitions are discussed. It is pointed out that in several phase transitions, the observed diffuse scatterings can not be interpreted in terms of critical fluctuations of the order parameters associated with the structural phase transitions, and that they are rather interpreted as Huang scattering due to random distribution of individual order parameter which is 'dressed' by strain fields. Examples to show effective applications of this concept to analyze the experimental X-ray data and whence to understand microscopic mechanisms of structural phase transitions are presented. (author)
do Carmo, Eduardo; Goncalves Hönnicke, Marcelo
2018-05-01
There are different forms to introduce/illustrate the energy concepts for the basic physics students. The explosive seed dispersal mechanism found in a variety of trees could be one of them. Sibipiruna trees carry out fruits (pods) who show such an explosive mechanism. During the explosion, the pods throw out seeds several meters away. In this manuscript we show simple methodologies to estimate the energy amount stored in the Sibipiruna tree due to such a process. Two different physics approaches were used to carry out this study: by monitoring indoor and in situ the explosive seed dispersal mechanism and by measuring the elastic constant of the pod shell. An energy of the order of kJ was found to be stored in a single tree due to such an explosive mechanism.
Change of mechanical properties of Norway Spruce wood due to degradation caused by fire retardants
Czech Academy of Sciences Publication Activity Database
Kloiber, Michal; Frankl, Jiří; Drdácký, Miloš; Kučerová, I.; Tippner, J.; Bryscejn, Jan
2010-01-01
Roč. 55, č. 4 (2010), s. 23-38 ISSN 1336-4561 Grant - others:GAČR(CZ) GA103/07/1091 Program:GA Institutional research plan: CEZ:AV0Z20710524 Keywords : wood degradation * fire retardant * mechanical properties * tensile strength * hardness Subject RIV: JN - Civil Engineering Impact factor: 0.284, year: 2010
77 FR 41457 - Aging Management Associated With Wall Thinning Due to Erosion Mechanisms
2012-07-13
... Corrosion,'' based on the staff's review of several license renewal applications' flow-accelerated corrosion... address emergent issues not covered in license renewal guidance documents, such as the GALL Report and SRP... erosion mechanisms; (b) revise the definition of ``flow-accelerated corrosion'' and ``erosion'' to align...
Samochocki, Zbigniew; Owczarek, Witold; Rujna, Paweł; Raczka, Alicja
2007-01-01
Atopic dermatitis (AD) is a disease with a complex pathomechanism, it is very difficult to establish the exact factors which can either trigger or exacerbate the disease. Knowledge of the mechanisms involved in AD development can be increased by, among others, applying new diagnostic tests and careful assessment of the results obtained. The aim of this study was to determine the allergic mechanisms of hypersensitivity to selected aeroallergens in patients with AD. The study comprised 109 AD patients. In all the patients the total IgE level was measured and atopy patch tests and skin prick tests were performed. We also assessed the presence of specific IgE against house dust mite, birch-tree, mixed grass pollen and cat dander. The highest incidence of positive results was found for house dust mite allergens, irrespective of the test employed. Analysing hypersensitivity to all the examined allergens we revealed the presence of allergic mechanisms in 85.3% of the patients. In 30.2% of the examined individuals we proved a type I immunological response, in 45.9% -- both types I and IV in 9.2% -- only type IV in one patient. In 14.7% of the patients the results of all the tests performed were negative. Analysing hypersensitivity to particular aeroallergens, negative test results to house dust mite were observed in 25.8% of the patients. The percentage of positive results for birch pollen, grass pollen and cat dander were 45.0, 44.1 and 53.2, respectively. Analysis of the results showed that allergic reactions to the same aeroallergens may develop via different mechanisms. We also revealed that the coexistence of various mechanisms involved in the development of hypersensitivity to a particular aeroallergen may occur in individual patients.
Pathogenic mechanisms in chronic obstructive pulmonary disease due to biomass smoke exposure.
Silva, Rafael; Oyarzún, Manuel; Olloquequi, Jordi
2015-06-01
Chronic obstructive pulmonary disease (COPD) mortality and morbidity have increased significantly worldwide in recent decades. Although cigarette smoke is still considered the main risk factor for the development of the disease, estimates suggest that between 25% and 33% of COPD patients are non-smokers. Among the factors that may increase the risk of developing COPD, biomass smoke has been proposed as one of the most important, affecting especially women and children in developing countries. Despite the epidemiological evidence linking exposure to biomass smoke with adverse health effects, the specific cellular and molecular mechanisms by which this pollutant can be harmful for the respiratory and cardiovascular systems remain unclear. In this article we review the main pathogenic mechanisms proposed to date that make biomass smoke one of the major risk factors for COPD. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.
Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE
Directory of Open Access Journals (Sweden)
S. S. Cota
2007-06-01
Full Text Available This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates.
Phase transition in the rich-get-richer mechanism due to finite-size effects
International Nuclear Information System (INIS)
Bagrow, James P; Ben-Avraham, Daniel; Sun Jie
2008-01-01
The rich-get-richer mechanism (agents increase their 'wealth' randomly at a rate proportional to their holdings) is often invoked to explain the Pareto power-law distribution observed in many physical situations, such as the degree distribution of growing scale-free nets. We use two different analytical approaches, as well as numerical simulations, to study the case where the number of agents is fixed and finite (but large), and the rich-get-richer mechanism is invoked a fraction r of the time (the remainder of the time wealth is disbursed by a homogeneous process). At short times, we recover the Pareto law observed for an unbounded number of agents. In later times, the (moving) distribution can be scaled to reveal a phase transition with a Gaussian asymptotic form for r<1/2, and a Pareto-like tail (on the positive side) and a novel stretched exponential decay (on the negative side) for r<1/2
Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE)
International Nuclear Information System (INIS)
Cota, S.S.; Vasconcelos, V.; Senne Junior, M.; Carvalho, L.L.; Rezende, D.B.; Correa, R.F.
2007-01-01
This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE) samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates. (author)
Investigation of Triplet Exciplex Dynamics by Magnetic Field Effects due to the Triplet Mechanism
Ulrich, T.; Steiner, Ulrich; Föll, Rudolf E.
1983-01-01
A reaction scheme is described allowing for magnetic field effects on the chemical kinetics of triplet reactions due to the selective decay of triplet sublevels. The theoretical treatment of this scheme is outlined on the basis of a stochastic Liouville equation, taking into account the rotational diffusion of molecules in liquid solution. Whereas the exact solution of the general case is obtained by a numerical procedure as described by Pedersen and Freed, an approximate analytical expressio...
Frolova, Irina; Agakhanov, Murad
2018-03-01
The development of computing techniques to analyze underground structures, buildings in high-rise construction that would fully take account of the conditions of their design and operation, as well as the real material properties, is one of the important trends in structural mechanics. For the territory in high-rise construction it is necessary to monitor the deformations of the soil surface. When high-rise construction is recommended to take into account the rheological properties and temperature deformations of the soil, the effect of temperature on the mechanical characteristics of the surrounding massif. Similar tasks also arise in the creation and operation of underground parts of high-rise construction, which are used for various purposes. These parts of the structures are surrounded by rock massifs of various materials. The actual mechanical characteristics of such materials must be taken into account. The objective property of nearly all materials is their non-homogeneity, both natural and technological. The work addresses the matters of building nonhomogeneous media initial models based on the experimental evidence. This made it possible to approximate real dependencies and obtain the appropriate functions in a simple and convenient way.
Mechanism of high-T{sub c} superconductivity studied by neutron scattering
Energy Technology Data Exchange (ETDEWEB)
Yamada, Kazuyoshi [Tohoku Univ., Sendai (Japan). Faculty of Science
1998-03-01
La{sub 2-x}Sr{sub x}CuO{sub 4} is one of the typical high-T{sub c} cuprates where Sr-doping creates many phases from the Mott insulator at x=0 nonsuperconducting metal for x>0.26; the high-T{sub c} superconductivity appears for 0.06{<=}x{<=}0.26. We have grown large single crystals of La{sub 2-x}Sr{sub x}CuO{sub 4} over a wide the doping rate up to x=0.3 and performed systematic neutron scattering experiments for the first time. We obtained several results indicating an intimate relation between the dynamical spin correlations and the superconductivity. Incommensurate spatial modulation appears in the antiferromagnetic spin correlations beyond x=0.05 close to the lower boundary of the superconducting phase. We found that the degree of the spatial modulation or the incommensurability {delta} increases with doping and T{sub c} is linearly scaled with {delta} for x{<=}0.15. A well-defined spin excitation gap was observed only for x=0.15 where the T{sub c} reaches the maximum value. And the dynamical spin coherence degrades upon doping with x>>0.15. There results strongly suggest the essential role of the magnetically correlated region and the spatial spin modulation in the CuO{sub 2} planes to sustain or create the superconductivity. (author)
Mechanism of Pseudogap Detected by Electronic Raman Scattering: Phase Fluctuation or Hidden Order?
International Nuclear Information System (INIS)
Hong-Yan, Lu; Yuan, Wan; Xiang-Mei, He; Qiang-Hua, Wang
2009-01-01
We study the electronic Raman scattering in the cuprates to distinguish the two possible scenarios of the pseudo-gap normal state. In one scenario, the pseudogap is assumed to be caused by phase fluctuations of the preformed Cooper pairs. We find that pair-breaking peaks appear in both the B 1g and B 2g Raman channels, and they are smeared and tend to shift to the same energy with the increasing strength of phase fluctuations. Thus both channels reflect the same pairing energy scale, irrespectively of the doping level. In another scenario, the pseudogap is assumed to be caused by a hidden order that competes with the superconducting order. As an example, we assume that the hidden order is the d-density-wave (DDW) order. We find analytically and numerically that in the DDW normal state there is no Raman peak in the B 2g channel in a tight-binding model up to the second nearest-neighbor hopping, while the Raman peak in the B 1g channel reflects the energy gap caused by the DDW order. This behavior is in agreement with experiments in the pseudogap normal state. To gain further insights, we also calculate the Raman spectra in the DDW+SC state. We study the doping and temperature dependence of the peak energy in both channels and find a two-gap behavior, which is in agreement with recent Raman experiments. Therefore, our results shed light on the hidden order scenario for the pseudogap
Degradation of the Mechanical Properties of Zirconium-base alloys due to Interaction with Hydrogen
International Nuclear Information System (INIS)
Bertolino, Graciela
2001-01-01
Security aspects and the purpose to extend the nuclear power plants lifetime motivate the renovated interest on the influence of the environment and radiation on the mechanical properties of in-reactor materials.Zirconium based alloys are the family of alloys most extensively used in nuclear core components.A consequence of the interaction of the in-reactor environment with these alloys is the formation of brittle phase Zr hydride, a process that greatly affects the component integrity.In this work we present a experimental study of the hydrogen influence on the Z ry-4 mechanical properties at different temperatures.As a complement we also present results of a finite elements simulations of the fracture process.We performed standard metallurgical and mechanical characterization in commercial Z ry-4 samples to obtain their basic properties. Different hydrogen pickup techniques were applied to obtain H concentration of charged samples between 10 and 2000 ppm, homogeneous or mainly localized at the crack tip zone.To obtain the fracture toughness of the alloys specimens were tested using elastoplastic fracture mechanics techniques.Specifically we implement J-integral methodology with partial unloading compliance measurements.Tests were performed in a temperature range of 20 to 200 o C.The negative influence of the H content on material toughness probed to be important even at very small concentrations, with an effect that decreases when temperature increases.While there was observed no change in the fracture mechanism in homogeneous charged samples, specimens charged under a superimposed stress field fractured by brittle mode when were tested at 20 to 70 o C. SEM observations of the crack growth, the fracture surface morphology and precipitates content showed the influence of the precipitates on fracture at different H concentrations.At least three stages with different fracture behavior depending on H content were identified.Complementary to the experimental work we
International Nuclear Information System (INIS)
Wangler, M.
1978-01-01
By measuring cross section fluctuations in the area of heavily overlapping resonances (Ericson-fluctuations) one is able to extract nuclear properties like level width and level distance. For the elastic scattering case of polarized spin 1/2-particles at nuclei with zero spin one is able to determine the direct reaction part independently from the model by evaluating the polarized and unpolarized cross sections. For this reason the reaction 30 Si(p,p 0 ) and 30 Si(p,p 1 ) was measured with polarized protons in the angular range 50 0 0 , ΔTHETA = 10 0 . The bombarding energy was varied between 8.500 MeV and 10.680 MeV with 20 keV steps. A mean value of (18.5 +- 2.9) keV resulted for the coherence width that was in agreement for the measurements with polarized and unpolarized particles. To define a final value of the reaction mechanism in elastic scattering the direct part of reaction was determined for all angles. (orig.) [de
Nonlinear finite element analysis of the plantar fascia due to the windlass mechanism.
Cheng, Hsin-Yi Kathy; Lin, Chun-Li; Chou, Shih-Wei; Wang, Hsien-Wen
2008-08-01
Tightening of plantar fascia by passively dorsiflexing the toes during walking has functional importance. The purpose of this research was to evaluate the influence of big toe dorsiflexion angles upon plantar fascia tension (the windlass effect) with a nonlinear finite element approach. A two-dimensional finite element model of the first ray was constructed for biomechanical analysis. In order to imitate the windlass effect and to evaluate the mechanical responses of the plantar fascia under various conditions, 12 model simulations--three dorsiflexion angles of the big toe (45 degrees, 30 degrees, and 15 degrees), two plantar fascia properties (linear, nonlinear), and two weightbearing conditions (with body weight, without body weight)--were designed and analyzed. Our results demonstrated that nonlinear modeling of the plantar fascia provides a more sophisticated representation of experimental data than the linear one. Nonlinear plantar fascia setting also predicted a higher stress distribution along the fiber directions especially with larger toe dorsiflexion angles (45 degrees>30 degrees>15 degrees). The plantar fascia stress was found higher near the metatarsal insertion and faded as it moved toward the calcaneal insertion. Passively dorsiflexing the big toe imposes tension onto the plantar fascia. Windlass mechanism also occurs during stance phase of walking while the toes begin to dorsiflex. From a biomechanical standpoint, the plantar fascia tension may help propel the body upon its release at the point of push off. A controlled stretch via dorsiflexing the big toe may have a positive effect on treating plantar fasciitis by providing proper guidance for collagen regeneration. The windlass mechanism is also active during the stance phase of walking when the toes begin to dorsiflex.
Exponential energy growth due to slow parameter oscillations in quantum mechanical systems.
Turaev, Dmitry
2016-05-01
It is shown that a periodic emergence and destruction of an additional quantum number leads to an exponential growth of energy of a quantum mechanical system subjected to a slow periodic variation of parameters. The main example is given by systems (e.g., quantum billiards and quantum graphs) with periodically divided configuration space. In special cases, the process can also lead to a long period of cooling that precedes the acceleration, and to the desertion of the states with a particular value of the quantum number.
Genareau, K. D.; Cronin, S. J.; Stewart, C.; Back, E.
2015-12-01
Explosive volcanic eruptions are known to be a significant geohazard, but post- or inter-eruptive processes (such as lahars, landslides, and debris avalanches) can be equally damaging to local and regional areas by remobilizing deposits. Numerous studies have found that soluble salts bound to ash grain surfaces may be quickly released into exposed waters, often lowering pH and adding trace metals with both beneficial and deleterious effects on marine flora and fauna (e.g., Fe influx initiating blooms of marine phytoplankton). Most of the cation content of pyroclastic deposits is released slowly into the environment through weathering and alteration processes. However, other pathways exist through the physical comminution of pyroclasts in fluvial and marine settings. In this case, mechanical fracturing of pyroclasts during progressive stages of disaggregation will lead to exposure of reactive particle surfaces. This study evaluates the potential, ongoing effects on water quality by experimental, mechanical milling of pyroclasts and the evaluation of released metals into exposed waters using the pyroclastic density current deposits of both the 2010 eruption of Merapi and the 2014 eruption of Kelud (Java, Indonesia), which have a bulk basaltic andesite/andesite composition (60-65 wt% SiO2). The electrical conductivity (EC) of water samples positively correlates with Ca and Sr concentrations in the case of bulk ash, whole, and crushed lapilli, but correlates with Na for the milled samples. Compared to other stages of pyroclast disaggregation, milled lapilli have the greatest effect on the concentration of alkali elements and produce a significant increase in Ca, Na, K, and Si. Mechanical milling of pyroclasts grinds down minerals and glass, resulting in an increased EC, pH, and Na concentration of exposed waters. Similar experiments are currently being conducted using basalt (50 wt% SiO2) and rhyolite (70 wt% SiO2) deposits, and these results will be presented
Hamim, Salah Uddin Ahmed
2011-12-01
Epoxy polymers are an important class of material for use in various applications. Due to their hydrophilic nature, epoxy resins tend to absorb moisture. Absorption of moisture degrades the functional, structural and mechanical properties. For polymers, moisture absorption can lead to both reversible and irreversible changes. In this study, the combined effect of moisture and elevated temperature on the mechanical properties of Epon 862 and its nanocomposites were investigated. The extent of permanent damage on fracture toughness and flexural properties of epoxy, due to the aggressive degradation provided by hygrothermal ageing, was determined by drying the epoxy and their clay/epoxy nanocomposites after moisture absorption. From the investigation it was found out that, clay can help in reducing the negative effect of hygrothermal ageing. Significant permanent damage was observed for fracture toughness and modulus, while the extent of permanent damage was less significant for flexural strength. Failure mechanism of this nanocomposites were studied by using Scanning Electron Microscopy (SEM).
International Nuclear Information System (INIS)
Elcombe, C.R.; Mitchell, A.M.
1986-01-01
The exposure of cultured rat hepatocytes to mono(2-ethyhexyl)phthalate (MEHP) for 72 hr resulted in marked induction of peroxisomal enzyme activity (β-oxidation; cyanide-insensitive palmitoyl CoA oxidase) and concomitant increases in the number of peroxisomes. Similar treatment of cultured guinea pig, marmoset, or human hepatocytes revealed little or no effect of MEHP. In order to eliminate possible confounding influences of biotransformation, the proximate peroxisome proliferator(s) derived from MEHP have been identified. Using cultured hepatocytes these agents were found to be metabolite VI [mono(2-ethyl-5-oxohexyl) phthalate] and metabolite IX [mono(2-ethyl-5-hydroxyhexyl) phthalate]. The addition of these active metabolites to cultured guinea pig, marmoset, or human hepatocytes again revealed little effect upon peroxisomes or related enzyme activities (peroxisomal β-oxidation or microsomal lauric acid hydroxylation). These studies demonstrate a marked species difference in the response of hepatocytes to MEHP-elicited peroxisome proliferation. Preliminary studies have also suggested that peroxisome proliferation due to MEHP may be due to an initial biochemical lesion of fatty acid metabolism
Chen, Si; Tong, Xiaoqian; He, Huiwen; Ma, Meng; Shi, Yanqin; Wang, Xu
2017-04-05
A kind of body temperature controlled optical and thermal information storage light scattering display based on super strong liquid crystalline physical gel with special "loofah-like gel network" was successfully prepared. Such liquid crystal (LC) gel was obtained by mixing a dendritic gelator (POSS-G1-BOC), an azobenzene compound (2Azo2), and a phosphor tethered liquid crystalline host (5CB), which could show its best contrast ratio at around human body temperature under UV light because of the phosphor's fluorescence effect. The gel also has quite strong mechanical strength, which could be used in wearable device field especially under sunlight, even under the forcing conditions as harsh as being centrifuged for 10 min at the speed of 2000 r/min. The whole production process of such a display is quite simple and could lead to displays at any size through noncontact writing. We believe it will have wide applications in the future.
International Nuclear Information System (INIS)
Chatterjee, Alok; Kalia, Rajiv K.; Nakano, Aiichiro; Omeltchenko, Andrey; Tsuruta, Kenji; Vashishta, Priya; Loong, Chun-Keung; Winterer, Markus; Klein, Sylke
2000-01-01
Structure, mechanical properties, and sintering of nanostructured SiC (n-SiC) are investigated with neutron scattering and molecular-dynamics (MD) techniques. Both MD and the experiment indicate the onset of sintering around 1500 K. During sintering, the pores shrink while maintaining their morphology: the fractal dimension is ∼2 and the surface roughness exponent is ∼0.45. Structural analyses reveal that interfacial regions in n-SiC are disordered with nearly the same number of three- and fourfold coordinated Si atoms. The elastic moduli scale with the density as ∼ρ μ , where μ=3.4±0.1. (c) 2000 American Institute of Physics
Three-dimensional quantum mechanical studies of D+H2 → HD+H reactive scattering. II
International Nuclear Information System (INIS)
Choi, B.H.; Tang, K.T.
1975-01-01
Three-dimensional quantum mechanical calculations are carried out for the reactive scattering of D+H 2 →DH+H on the Yates--Lester potential surface. The differential and total cross sections as well as the S-matrix elements are obtained and are compared with the corresponding results obtained on the Porter--Karplus potential surface. The differential cross sections and the distributions over final angular momentum states are in much better agreement with the experimental measurements than the previous results obtained on the Porter--Karplus surface. However, the calculated threshold energy for the reaction seems too high whereas the threshold on the Porter--Karplus potential seems too low. These dynamic attributes are discussed in terms of the two-body potentials between the atom and the molecule
Quantum mechanical calculations of reactive scattering cross sections in bimolecular encounters
Pirkle, J. C., Jr.
1967-01-01
Study applies the nonequilibrium collision theory of reaction rates to the estimation of rate constants for simple reactions. The complications in the quantum mechanical description of chemical reactions and the care needed in approximating the exact wave function for the collision are shown.
Settlement mechanism of piled-raft foundation due to cyclic train loads and its countermeasure
Gu, Linlin; Ye, Guanlin; Wang, Zhen; Ling, Xianzhang; Zhang, Feng
2017-07-01
In this paper, numerical simulation with soil-water coupling finite element-finite difference (FE-FD) analysis is conducted to investigate the settlement and the excess pore water pressure (EPWP) of a piled-raft foundation due to cyclic high-speed (speed: 300km/h) train loading. To demonstrate the performance of this numerical simulation, the settlement and EPWP in the ground under the train loading within one month was calculated and confirmed by monitoring data, which shows that the change of the settlement and EPWP can be simulated well on the whole. In order to ensure the safety of train operation, countermeasure by the fracturing grouting is proposed. Two cases are analyzed, namely, grouting in No-4 softest layer and No-9 pile bearing layer respectively. It is found that fracturing grouting in the pile bearing layer (No-9 layer) has better effect on reducing the settlement.
Directory of Open Access Journals (Sweden)
Wendy Margarita Chávez-Montes
2016-04-01
Full Text Available Thermal stability as well as enhanced mechanical properties of poly-lactide (PLA can increase PLA applications for short-use products. The conjunction of adequate molecular weight (MW as well as satisfactory thermo-mechanical properties, together, can lead to the achievement of suitable properties. However, PLA is susceptible to thermal degradation and thus an undesired decay of MW and a decrease of its mechanical properties during processing. To avoid this PLA degradation, nanofiller is incorporated as reinforcement to increase its thermo-mechanical properties. There are many papers focusing on filler effects on the thermal stability and mechanical properties of PLA/nanocomposites; however, these investigations lack an explanation of polymer/filler interactions. We propose interactions between PLA and Cloisite30B (C30B as nanofiller. We also study the effects on the thermal and mechanical properties due to molecular weight decay after exposure to artificial weathering. PLA blank and nanocomposites were subjected to three time treatments (0, 176, and 360 h of exposure to artificial weathering in order to achieve comparable materials with different MW. MW was acquired by means of Gel Permeation Chromatography (GPC. Thermo-mechanical properties were investigated through Thermogravimetric Analysis (TGA, Differential Scanning Calorimetry (DSC, X-ray Diffraction (XRD, Dynamic Mechanical Thermal Analysis (DMTA and Fourier Transform Infrared Spectroscopy (FTIR.
[Influence of mechanical effect due to MRI-magnet on tattoo seal and eye makeup].
Morishita, Yuta; Miyati, Tosiaki; Ueda, Jousei; Shimizu, Mitsuru; Hamaguchi, Takashi; Fujiwara, Yasuhiro; Hayashi, Hiroyuki
2008-05-20
The purpose of our study was to assess the mechanical effect on tattoo seals and eye makeup caused by a spatial magnetic gradient in the magnetic resonance imaging (MRI) system. Seven kinds of tattoo seals and three kinds of eye makeup, i.e., mascara, eye shadow, and eyeliner were used. On a 3.0-Tesla MRI, we determined these deflection angles according to a method established by the American Society for Testing and Materials (ASTM) at the position that produced the greatest magnetically induced deflection. Eighty-five percent of the tattoo seals showed deflection angles greater than 45 degrees of the ASTM guidelines, and the mascara and eye shadow showed over 40 degrees. This was because these contained ferromagnetic pigments such as an iron oxide, but those translational forces were very small owing to slight mass. However, it is desirable that these should be removed before MRI examination to prevent secondary problems.
International Nuclear Information System (INIS)
Montazer, P.
1985-01-01
One of the effects of excavating an underground opening in fractured rocks is a modification of the state of the stress in the rock mass in the vicinity of the opening. This effect causes changes in the geometry of the cross sections of the fracture planes, which in turn results in modification of the hydrologic properties of the fractures of the rock mass. The significance of the orientation of the fractures and their stiffness on the extent of the modification of the hydrologic properties as a result of excavation of underground openings is demonstrated. A conceptual model is presented to illustrate the complexity of the coupled hydrological-mechanical phenomena in the unsaturated zone. This conceptual model is used to develop an investigative program to assess the extent of the effect at a proposed repository site for storing high-level nuclear wastes
A heating mechanism of ions due to large amplitude coherent ion acoustic wave
International Nuclear Information System (INIS)
Yajima, Nobuo; Kawai, Yoshinobu; Kogiso, Ken.
1978-05-01
Ion heating mechanism in a plasma with a coherent ion acoustic wave is studied experimentally and numerically. Ions are accelerated periodically in the electrostatic potential of the coherent wave and their oscillation energy is converted into the thermal energy of ions through the collision with the neutral atoms in plasma. The Monte Carlo calculation is applied to obtain the ion temperature. The amplitude of the electrostatic potential, the mean number of collisions and the mean life time of ions are treated as parameters in the calculation. The numerical results are compared with the experiments and both of them agree well. It is found that the ion temperature increases as the amplitude of the coherent wave increases and the high energy tail in the distribution function of ions are observed for the case of large wave-amplitude. (author)
Influence of mechanical effect due to MRI-magnet on tattoo seal and eye makeup
International Nuclear Information System (INIS)
Morishita, Yuta; Ueda, Jousei; Miyati, Tosiaki; Hamaguchi, Takashi; Shimizu, Mitsuru; Fujiwara, Yasuhiro; Hayashi, Hiroyuki
2008-01-01
The purpose of our study was to assess the mechanical effect on tattoo seals and eye makeup caused by a spatial magnetic gradient in the magnetic resonance imaging (MRI) system. Seven kinds of tattoo seals and three kinds of eye makeup, i.e., mascara, eye shadow, and eyeliner were used. On a 3.0-Tesla MRI, we determined these deflection angles according to a method established by the American Society for Testing and Materials (ASTM) at the position that produced the greatest magnetically induced deflection. Eighty-five percent of the tattoo seals showed deflection angles greater than 45 degrees of the ASTM guidelines, and the mascara and eye shadow showed over 40 degrees. This was because these contained ferromagnetic pigments such as an iron oxide, but those translational forces were very small owing to slight mass. However, it is desirable that these should be removed before MRI examination to prevent secondary problems. (author)
Rasool, Nouman; Iftikhar, Saima; Amir, Anam; Hussain, Waqar
2018-03-01
Pyrazinamide is known to be the most effective treatment against tuberculosis disease and is known to have bacteriostatic action. By targeting the bacterial spores, this drug reduces the chances for the progression of the infection in organisms. In recent years, increased instances of the drug resistance of bacterial strains are reported. Pyrazinamidase, activator for pyrazinamide, leads to resistance against the drug due to mutagenicity across the world. The present study aimed at the quantum mechanistic analysis of mutations in pyrazinamidase to gain insights into the mechanism of this enzyme. Quantum mechanical calculations were performed to analyse the effect of mutations at the metal coordination site using ORCA software program. Moreover, conformational changes in PZase binding cavity has also been analysed due to mutations of binding pocket residues using CASTp server. In order to elucidate the behaviour of the mutant pyrazinamidase, docking of PZA in the binding pocket of PZase was performed using AutoDock Vina. Analysis of results revealed that iron showed weak binding with the metal coordination site of the mutant proteins due to alteration in electron transfer mechanism. The binding cavity of the mutant PZase has undergone major conformational changes as the volume of pocket increased due to bulky R-chains of mutated amino acids. These conformational changes lead to weak binding of the drug at binding cavity of PZase and reduce the drug activation mechanism leading to increased drug resistance in the bacterial strains. Copyright © 2017 Elsevier Inc. All rights reserved.
de Carvalho, Alberito Rodrigo; Andrade, Alexandro; Peyré-Tartaruga, Leonardo Alexandre
2015-01-01
One goal of the locomotion is to move the body in the space at the most economical way possible. However, little is known about the mechanical and energetic aspects of locomotion that are affected by low back pain. And in case of occurring some damage, little is known about how the mechanical and energetic characteristics of the locomotion are manifested in functional activities, especially with respect to the energy-minimizer mechanisms during locomotion. This study aimed: a) to describe the main energy-minimizer mechanisms of locomotion; b) to check if there are signs of damage on the mechanical and energetic characteristics of the locomotion due to chronic low back pain (CLBP) which may endanger the energy-minimizer mechanisms. This study is characterized as a narrative literature review. The main theory that explains the minimization of energy expenditure during the locomotion is the inverted pendulum mechanism, by which the energy-minimizer mechanism converts kinetic energy into potential energy of the center of mass and vice-versa during the step. This mechanism is strongly influenced by spatio-temporal gait (locomotion) parameters such as step length and preferred walking speed, which, in turn, may be severely altered in patients with chronic low back pain. However, much remains to be understood about the effects of chronic low back pain on the individual's ability to practice an economic locomotion, because functional impairment may compromise the mechanical and energetic characteristics of this type of gait, making it more costly. Thus, there are indications that such changes may compromise the functional energy-minimizer mechanisms. Copyright © 2014 Elsevier Editora Ltda. All rights reserved.
Choi, Yong-Min; Kim, Han-Kyul; Shim, Wooyoung; Anwar, Muhammad Ayaz; Kwon, Ji-Woong; Kwon, Hyuk-Kwon; Kim, Hyung Joong; Jeong, Hyobin; Kim, Hwan Myung; Hwang, Daehee; Kim, Hyung Sik; Choi, Sangdun
2015-01-01
The chemotherapeutic use of cisplatin is limited by its severe side effects. In this study, by conducting different omics data analyses, we demonstrated that cisplatin induces cell death in a proximal tubular cell line by suppressing glycolysis- and tricarboxylic acid (TCA)/mitochondria-related genes. Furthermore, analysis of the urine from cisplatin-treated rats revealed the lower expression levels of enzymes involved in glycolysis, TCA cycle, and genes related to mitochondrial stability and confirmed the cisplatin-related metabolic abnormalities. Additionally, an increase in the level of p53, which directly inhibits glycolysis, has been observed. Inhibition of p53 restored glycolysis and significantly reduced the rate of cell death at 24 h and 48 h due to p53 inhibition. The foremost reason of cisplatin-related cytotoxicity has been correlated to the generation of mitochondrial reactive oxygen species (ROS) that influence multiple pathways. Abnormalities in these pathways resulted in the collapse of mitochondrial energy production, which in turn sensitized the cells to death. The quenching of ROS led to the amelioration of the affected pathways. Considering these observations, it can be concluded that there is a significant correlation between cisplatin and metabolic dysfunctions involving mROS as the major player.
Mechanisms of Gait Asymmetry Due to Push-Off Deficiency in Unilateral Amputees.
Adamczyk, Peter Gabriel; Kuo, Arthur D
2015-09-01
Unilateral lower-limb amputees exhibit asymmetry in many gait features, such as ground force, step time, step length, and joint mechanics. Although these asymmetries result from weak prosthetic-side push-off, there is no proven mechanistic explanation of how that impairment propagates to the rest of the body. We used a simple dynamic walking model to explore possible consequences of a unilateral impairment similar to that of a transtibial amputee. The model compensates for reduced push-off work from one leg by performing more work elsewhere, for example during the middle of stance by either or both legs. The model predicts several gait abnormalities, including slower forward velocity of the body center-of-mass during intact-side stance, greater energy dissipation in the intact side, and more positive work overall. We tested these predictions with data from unilateral transtibial amputees (N = 11) and nonamputee control subjects (N = 10) walking on an instrumented treadmill. We observed several predicted asymmetries, including forward velocity during stance phases and energy dissipation from the two limbs, as well as greater work overall. Secondary adaptations, such as to reduce discomfort, may exacerbate asymmetry, but these simple principles suggest that some asymmetry may be unavoidable in cases of unilateral limb loss.
Energy Technology Data Exchange (ETDEWEB)
Andrade Landeta, J.; Lascano, I.
2017-07-01
A theorical model has been developed based on the theory of Ginzburg-Landau-Devonshire to study and predict the effects the decreasing of size particle in a nanosphere of PbTiO3 subjected to the action of depolarization fields and mechanical stress. It was considered that the nanosphere is surrounded by a layer of space charges on its surface, and containing 180° domains generated by minimizing free energy of depolarization. Energy density of depolarization, wall domain and electro-elastic energy have been incorporated into the free energy of the theory Ginzburg-Landau-Devonshire. Free energy minimization was performed to determine the spontaneous polarization and transition temperature system. These results show that the transition temperature for nanosphere is substantially smaller than the corresponding bulk material. Also, it has been obtained that the stability of the ferroelectric phase of nanosphere is favored for configurations with a large number of 180° domains, with the decreasing of thickness space charge layer, and the application of tensile stress and decreases with compressive stress. (Author)
Modeling mechanisms of vegetation change due to fire in a semi-arid ecosystem
White, J.D.; Gutzwiller, K.J.; Barrow, W.C.; Randall, L.J.; Swint, P.
2008-01-01
Vegetation growth and community composition in semi-arid environments is determined by water availability and carbon assimilation mechanisms specific to different plant types. Disturbance also impacts vegetation productivity and composition dependent on area affected, intensity, and frequency factors. In this study, a new spatially explicit ecosystem model is presented for the purpose of simulating vegetation cover type changes associated with fire disturbance in the northern Chihuahuan Desert region. The model is called the Landscape and Fire Simulator (LAFS) and represents physiological activity of six functional plant types incorporating site climate, fire, and seed dispersal routines for individual grid cells. We applied this model for Big Bend National Park, Texas, by assessing the impact of wildfire on the trajectory of vegetation communities over time. The model was initialized and calibrated based on landcover maps derived from Landsat-5 Thematic Mapper data acquired in 1986 and 1999 coupled with plant biomass measurements collected in the field during 2000. Initial vegetation cover change analysis from satellite data showed shrub encroachment during this time period that was captured in the simulated results. A synthetic 50-year climate record was derived from historical meteorological data to assess system response based on initial landcover conditions. This simulation showed that shrublands increased to the detriment of grass and yucca-ocotillo vegetation cover types indicating an ecosystem-level trajectory for shrub encroachment. Our analysis of simulated fires also showed that fires significantly reduced site biomass components including leaf area, stem, and seed biomass in this semi-arid ecosystem. In contrast to other landscape simulation models, this new model incorporates detailed physiological responses of functional plant types that will allow us to simulated the impact of increased atmospheric CO2 occurring with climate change coupled with fire
Calik, Eyup Serhat; Limandal, Husnu Kamil; Arslan, Umit; Tort, Mehmet; Yildiz, Ziya; Bayram, Ednan; Dag, Ozgur; Kaygin, Mehmet Ali; Erkut, Bilgehan
2015-12-14
Leaflet escape of prosthetic valve is rare but potentially life threatening. Early diagnosis is essential on account of avoiding mortality, and emergency surgical correction is compulsory. This complication has previously been reported for both monoleaflet and bileaflet valve models. A 30-year-old man who had undergone mitral valve replacement with a bileaflet valve 8 years prior at another center was admitted with acute-onset with cardiogenic shock as an emergency case. Transthoracic echocardiograms showed acute-starting severe mitral regurgitation associated with prosthetic mitral valve. There was a suspicious finding of a single prosthetic mitral leaflet. But the problem related with the valve wasn't specifically determined. The patient underwent emergent surgery for replacement of the damaged prosthetic valves immediately. There was no tissue impingement and thrombosis, one of the two leaflets was absent, and there were no signs of endocarditis or pannus formation in the prosthetic valve. The missing leaflet could not be found within the cardiac cavity. The abdominal fluoroscopic study and plain radiography were unable to detect the escaped leaflet during surgery. The damaged valve was removed and a replacement 29 mm bileaflet mechanical valve was inserted by right lateral thoracotomy. After post-operative week one, the abdominal computed tomography scan and the ultrasound showed the escaped leaflet in the left femoral artery. Fifteen days after the surgery the escaped leaflet was removed safely from the left femoral artery and the patient made a complete recovery. The escaped leaflet showed a fracture of one of the pivot systems caused by structural failure. Early cardiac surgery should be applied because of life-threatening problems.
Okandan, Murat
In the CMOS technology the gate dielectric is the most critical layer, as its condition directly dictates the ultimate performance of the devices. In this thesis, the wear-out and failure mechanisms in ultra-thin (around 50A and lower) oxides are investigated. A new degradation phenomenon, quasi-breakdown (or soft-breakdown), and the annealing and stressing behavior of devices after quasi-breakdown are considered in detail. Devices that are in quasi-breakdown continue to operate as switches, but the gate leakage current is two orders of magnitude higher than the leakage in healthy devices and the stressing/annealing behavior of the devices are completely altered. This phenomenon is of utmost interest, since the reduction in SiO2 dielectric thickness has reached its physical limits, and the quasi-breakdown behavior is seen to dominate as a failure mode in this regime. The quasi-breakdown condition can be brought on by stresses during operation or processing. To further study this evolution through stresses and anneals, cyclic current-voltage (I-V) measurement has been further developed and utilized in this thesis. Cyclic IV is a simple and fast, two terminal measurement technique that looks at the transient current flowing in an MOS system during voltage sweeps from accumulation to inversion and back. During these sweeps, carrier trapping/detrapping, generation and recombination are observed. An experimental setup using a fast electrometer and analog to digital conversion (A/D) card and the software for control of the setup and data analysis were also developed to gain further insight into the detailed physics involved. Overall, the crucial aspects of wear-out and quasi-breakdown of ultrathin dielectrics, along with the methods for analyzing this evolution are presented in this thesis.
Energy Technology Data Exchange (ETDEWEB)
Kim, Yong Rae; Yan, Jieshen; Kim, Jae-Woong [Yeungnam Univ., Gyeongsan (Korea, Republic of); Song, Gyu Yeong [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)
2017-01-15
Welding deformation is a permanent deformation that is caused in structures by welding heat. Welding distortion is the primary cause of reduced productivity, due to welded structural strength degradation, low dimensional accuracy, and appearance. As a result, research and numerous experiments are being carried out to control welding deformation. The aim of this study is to analyze the mechanism of longitudinal bending deformation due to welding. Welding experiments and numerical analyses were performed for this study. The welding experiments were performed on 4 mm and 8.5 mm thickness steel plates, and the numerical analysis was conducted on the welding deformation using the FE software MSC.marc.
Norsworthy, Mark A.; Ruch, Marc L.; Hamel, Michael C.; Clarke, Shaun D.; Hausladen, Paul A.; Pozzi, Sara A.
2018-03-01
We present the first measurements of energy-dependent light output from carbon recoils in the liquid organic scintillator EJ-309. For this measurement, neutrons were produced by an associated particle deuterium-tritium generator and scattered by a volume of EJ-309 scintillator into stop detectors positioned at four fixed angles. Carbon recoils in the scintillator were isolated using triple coincidence among the associated particle detector, scatter detector, and stop detectors. The kinematics of elastic and inelastic scatter allowed data collection at eight specific carbon recoil energies between 2.86 and 3.95 MeV. We found the light output caused by carbon recoils in this energy range to be approximately 1.14% of that caused by electrons of the same energy, which is comparable to the values reported for other liquid organic scintillators. A comparison of the number of scattered neutrons at each angle to a Monte Carlo N-Particle eXtended simulation indicates that the ENDF/B-VII.1 evaluation of differential cross sections for 14.1 MeV neutrons on carbon has discrepancies with the experiment as large as 55%, whereas those reported in the JENDL-4.0u evaluation agree with experiment.
Wood, Kathleen; Tobias, Douglas J.; Kessler, Brigitte; Gabel, Frank; Oesterhelt, Dieter; Mulder, Frans A. A.; Zaccai, Giuseppe; Weik, Martin
2010-01-01
There is increasing interest in the contribution of methyl groups to the overall dynamics measured by neutron scattering experiments of proteins. In particular an inflection observed in atomic mean square displacements measured as a function of temperature on high resolution spectrometers (similar
Kleinpoppen, Hans; Grum-Grzhimailo, Alexei N
2013-01-01
The main goal of this book is to elucidate what kind of experiment must be performed in order to determine the full set of independent parameters which can be extracted and calculated from theory, where electrons, photons, atoms, ions, molecules, or molecular ions may serve as the interacting constituents of matter. The feasibility of such perfect' and-or `complete' experiments, providing the complete quantum mechanical knowledge of the process, is associated with the enormous potential of modern research techniques, both, in experiment and theory. It is even difficult to overestimate the role of theory in setting of the complete experiment, starting with the fact that an experiment can be complete only within a certain theoretical framework, and ending with the direct prescription of what, and in what conditions should be measured to make the experiment `complete'. The language of the related theory is the language of quantum mechanical amplitudes and their relative phases. This book captures the spi...
International Nuclear Information System (INIS)
Hans-Joachim, Frank
2001-01-01
In the frame of European harmonization, a lot of changes on requirements for designer and manufacturer of mechanical components have been performed. Differed organizations are involved in preparing future requirements for nuclear application. On one side the French German cooperation on the development of EPR. At the origin of this project was the common decision in 1989 of Framatome and Siemens to cooperate through NPI, to design the Nuclear Island, which meets the future needs of utilities. EDF and a group of the main German Utilities joined this cooperation in 1991 and since then they have been totally involved to the progress of the work. In addition, all the process was backed up to the end by the strong cooperation between the French and the German. Safety Authorities, which have a long lasting cooperation to define common requirements, which have to be applied to future Nuclear Power Plants. Furthermore an organization has been set up to elaborate common codes related to the EPR design, at the level of the French design and construction rules (RCC) or the German KTA safety standards, the so-called EPR technical codes (ETC). On the other side, the European utilities co-operate on a much broader basis for the establishment of European Utilities Requirements (EUR). These requirements are prepared by a group of European utilities that represent the major European electricity generating companies that are determined to keep the nuclear option open. The technical requirements specified in the EUR document define the boundaries in which future plants need to be designed in order to be acceptable for the needs of the utilities and in order to fulfill the basic requirements of competitive power generation costs and licensability in all countries represented in the EUR group. All the new requirements have to be applied by designer and manufacturer. Siemens /SNP act as a designer of a lot of various vessels and tanks, heat exchangers and other items of process
International Nuclear Information System (INIS)
Ramani, D.T.
1977-01-01
The importance of knowledge of structural integrity of a reactor vessel due to thermal shock effects, is related to safety and operational requirements in assessing the adequacy and flawless functioing of the nuclear power systems. Followig a loss-of-coolant accident (LOCA) condition the integrity of the reactor vessel due to a sudden thermal shock induced by actuation of emergency core cooling system (ECCS), must be maintained to ensure safe and orderly shutdown of the reactor and its components. The paper encompasses criteria underlaying a fracture mechanics method of analysis to evaluate structural integrity of a typical 950 MWe PWR vessel as a result of very drastic changes in thermal and mechanical stress levels in the reactor vessel wall. The main object of this investigation therefore consists in assessing the capability of a PWR vessel to withstand the most critical thermal shock without inpairing its ability to conserve vital coolant owing to probable crack propagation. (Auth.)
International Nuclear Information System (INIS)
Martinschitz, K.
2005-06-01
Biological materials represent hierarchical nano fibre composites with complicated morphology and architecture varying on the nm level. The mechanical response of those materials is influenced by many parameters like chemical composition and crystal structure of constituents, preferred orientation, internal morphology with specific sizes of features etc. In-situ wide-angle x-ray scattering (WAXS) combined with mechanical tests provide a unique means to evaluate structural changes in biological materials at specific stages of tensile experiments. In this way it is possible to identify distinct architectural/compositional elements responsible for specific mechanical characteristics of the biological materials. In this thesis, structure-property relationship is analyzed using in-situ WAXS in the tissues of Picea abies, coir fibre, bacterial cellulose and cellulose II based composites. The experiments were performed at the beamline ID01 of European synchrotron radiation facility in Grenoble, France. The tissues were strained in a tensile stage, while the structural changes were monitored using WAXS. Complex straining procedures were applied including cyclic straining. One of the main goals was to understand the stiffness recovery and strain hardening effects in the tissues. The results demonstrate that, in all cellulosics, the orientation of the cellulose crystallites is only the function of the external strain while the stiffness depends on the specific stage of the tensile experiment. Whenever the strain is increased, the tissues exhibit stiffness equal or larger than the initial one. The recovery of the mechanical function is attributed to the molecular mechanistic effects operating between the crystalline domains of the cellulose. (author)
A. A. Panfilov
2013-01-01
The paper presents the results of laboratory experiments on electromagnetic emission excitation (electric component of electromagnetic field) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, cha...
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Akihisa, E-mail: ayamamoto@icems.kyoto-u.ac.jp, E-mail: tanaka@uni-heidelberg.de; Tanaka, Motomu, E-mail: ayamamoto@icems.kyoto-u.ac.jp, E-mail: tanaka@uni-heidelberg.de [Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120 Heidelberg (Germany); Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto 606-8501 (Japan); Abuillan, Wasim; Körner, Alexander [Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120 Heidelberg (Germany); Burk, Alexandra S. [Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120 Heidelberg (Germany); Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Ries, Annika [Institute of Organic and Biomolecular Chemistry, University of Göttingen, 37077 Göttingen (Germany); Werz, Daniel B. [Institute of Organic Chemistry, Technische Universität Braunschweig, 38106 Braunschweig (Germany); Demé, Bruno [Institut Laue-Langevin, 38042 Grenoble Cedex 9, Grenoble (France)
2015-04-21
The mechanical properties of multilayer stacks of Gb3 glycolipid that play key roles in metabolic disorders (Fabry disease) were determined quantitatively by using specular and off-specular neutron scattering. Because of the geometry of membrane stacks deposited on planar substrates, the scattered intensity profile was analyzed in a 2D reciprocal space map as a function of in-plane and out-of-plane scattering vector components. The two principal mechanical parameters of the membranes, namely, bending rigidity and compression modulus, can be quantified by full calculation of scattering functions with the aid of an effective cut-off radius that takes the finite sample size into consideration. The bulkier “bent” Gb3 trisaccharide group makes the membrane mechanics distinctly different from cylindrical disaccharide (lactose) head groups and shorter “bent” disaccharide (gentiobiose) head groups. The mechanical characterization of membranes enriched with complex glycolipids has high importance in understanding the mechanisms of diseases such as sphingolipidoses caused by the accumulation of non-degenerated glycosphingolipids in lysosomes or inhibition of protein synthesis triggered by the specific binding of Shiga toxin to Gb3.
Lamaignère, Laurent; Gaudfrin, Kévin; Donval, Thierry; Natoli, Jeanyves; Sajer, Jean-Michel; Penninckx, Denis; Courchinoux, Roger; Diaz, Romain
2018-04-30
Forward pump pulses with nanosecond duration are able to generate an acoustic wave via electrostriction through a few centimeters of bulk silica. Part of the incident energy is then scattered back on this sound wave, creating a backward Stokes pulse. This phenomenon known as stimulated Brillouin scattering (SBS) might induce first energy-loss, variable change of the temporal waveform depending on the location in the spatial profile making accurate metrology impossible, and moreover it might also initiate front surface damage making the optics unusable. Experiments performed on thick fused silica optics at 355 nm with single longitudinal mode pulses allowed us to detect, observe and quantify these backward pulses. Experimental results are first compared to theoretical calculations in order to strengthen our confidence in metrology. On this basis a phase-modulator has been implemented on the continuous-wave seeders of the lasers leading to pulses with a wide spectrum that suppress SBS and do not exhibit temporal overshoots that also reduce Kerr effects. The developed set-ups are used to check the reduction of the backward stimulated Brillouin scattering and they allow measuring with accuracy the rear surface damage of thick fused silica optics.
International Nuclear Information System (INIS)
Lee, Changwon; Park, Sukyung
2012-01-01
Stereocilia are the basic sensory units of nature's inertial sensors and are highly sensitive over broad dynamic ranges, which is a major challenge in the design of conventional engineering sensors. The high sensitivity that is maintained by stereocilia was hypothesized to exist due to a combination of adaptation and negative stiffness mechanisms, which shift the region of highest sensitivity toward the active operation range of the stereocilia bundle. To examine the adaptation hypothesis in terms of its potential applicability to future applications regarding the design of inertial sensors, we developed a mechanical mimicry of the interplay between negative stiffness and the adaptation of the stereocilia that produces spontaneous oscillation of the hair bundle. The mechanical model consists of an inverted pendulum and a fixed T-bar that mimic the interaction of two adjacent stereocilia. To focus on the interaction of one gating spring and the corresponding adaptation motor without the effect of coupling from the other gating springs attached to the neighboring stereocilia, we fixed one bar that contains the adaptation motor. To emulate the negative resistance of the tip-link due to the transient stiffness softening by the gating ion channel, a magnet pair was attached to the top of the inverted pendulum and the fixed T-bar. Readjustment of the tip-link tension by the ‘slipping down and climbing up’ motion of the adaptation molecular motors was demonstrated by the side-to-side movement of the magnet by a step motor. The negative stiffness region was observed near the equilibrium position and shifted with the activation of the adaptation motor. The temporal demonstration of the stiffness shift was measured as a spontaneous oscillation. The results showed that the interplay between the negative stiffness and the adaptation mechanism was mechanically produced by the combination of a repulsive force and its continuous readjustment and is better understood through a
Energy Technology Data Exchange (ETDEWEB)
Williams, Robert W. [Department of Biomedical Informatics, Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD 20815 (United States)], E-mail: bob@bob.usuhs.mil; Schluecker, Sebastian [Institute of Physical Chemistry, University of Wuerzburg, Wuerzburg (Germany); Hudson, Bruce S. [Department of Chemistry, Syracuse University, Syracuse, NY (United States)
2008-01-22
A scaled quantum mechanical harmonic force field (SQMFF) corrected for anharmonicity is obtained for the 23 K L-alanine crystal structure using van der Waals corrected periodic boundary condition density functional theory (DFT) calculations with the PBE functional. Scale factors are obtained with comparisons to inelastic neutron scattering (INS), Raman, and FT-IR spectra of polycrystalline L-alanine at 15-23 K. Calculated frequencies for all 153 normal modes differ from observed frequencies with a standard deviation of 6 wavenumbers. Non-bonded external k = 0 lattice modes are included, but assignments to these modes are presently ambiguous. The extension of SQMFF methodology to lattice modes is new, as are the procedures used here for providing corrections for anharmonicity and van der Waals interactions in DFT calculations on crystals. First principles Born-Oppenheimer molecular dynamics (BOMD) calculations are performed on the L-alanine crystal structure at a series of classical temperatures ranging from 23 K to 600 K. Corrections for zero-point energy (ZPE) are estimated by finding the classical temperature that reproduces the mean square displacements (MSDs) measured from the diffraction data at 23 K. External k = 0 lattice motions are weakly coupled to bonded internal modes.
International Nuclear Information System (INIS)
Williams, Robert W.; Schluecker, Sebastian; Hudson, Bruce S.
2008-01-01
A scaled quantum mechanical harmonic force field (SQMFF) corrected for anharmonicity is obtained for the 23 K L-alanine crystal structure using van der Waals corrected periodic boundary condition density functional theory (DFT) calculations with the PBE functional. Scale factors are obtained with comparisons to inelastic neutron scattering (INS), Raman, and FT-IR spectra of polycrystalline L-alanine at 15-23 K. Calculated frequencies for all 153 normal modes differ from observed frequencies with a standard deviation of 6 wavenumbers. Non-bonded external k = 0 lattice modes are included, but assignments to these modes are presently ambiguous. The extension of SQMFF methodology to lattice modes is new, as are the procedures used here for providing corrections for anharmonicity and van der Waals interactions in DFT calculations on crystals. First principles Born-Oppenheimer molecular dynamics (BOMD) calculations are performed on the L-alanine crystal structure at a series of classical temperatures ranging from 23 K to 600 K. Corrections for zero-point energy (ZPE) are estimated by finding the classical temperature that reproduces the mean square displacements (MSDs) measured from the diffraction data at 23 K. External k = 0 lattice motions are weakly coupled to bonded internal modes
Energy Technology Data Exchange (ETDEWEB)
Liebscher, S
1989-04-01
The change-over from underground to opencast operation in the Woelfersheim workings commenced in 1962 to ensure the coal supply to the power station that was expanded by a 64 MW unit. With due attention to soil mechanics features, a working scheme was evolved for the dredger-mobile conveyor-belt-stacker-system, which as regards the arrangement of the cuts takes into account not only the required output, but also the rock mechanics conditions in the Woelfersheim workings. Operational problems that occur in connection with changes to batter slopes are discussed in the present paper. After the coal has been worked-out in the individual sections of the field opencast residual pits remain, the slopes of which have to be stabilized by means of appropriate measures. (orig.).
Energy Technology Data Exchange (ETDEWEB)
Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, Canada N6A 3K7 (Canada)]. E-mail: msingh@uwo.ca
2007-03-26
We have investigated the switching mechanism due to the spontaneous emission cancellation in a photonic band gap (PBG) material doped with an ensemble of four-level nano-particles. The effect of the dipole-dipole interaction has also been studied. The linear susceptibility has been calculated in the mean field theory. Numerical simulations for the imaginary susceptibility are performed for a PBG material which is made from periodic dielectric spheres. It is predicted that the system can be switched between the absorbing state and the non-absorbing state by changing the resonance energy within the energy bands of the photonic band gap material.0.
Panfilov, A. A.
2014-06-01
The paper presents the results of laboratory experiments on electromagnetic emissions excitation (the electric component of electromagnetic fields) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, change with an increasing number of hits. It was found that strong electromagnetic signals, generated while rock samples were fracturing, were accompanied by repetitive weak but perceptible variations in the electric field intensity in short frequency ranges.
Energy Technology Data Exchange (ETDEWEB)
Wang, Yan [Univ. of Tennessee, Knoxville, TN (United States); Rademaker, Louk [Univ. of California, Santa Barbara, CA (United States); Dagotto, Elbio R. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnston, Steven [Univ. of Tennessee, Knoxville, TN (United States)
2017-08-18
Here, the discovery of an enhanced superconducting transition temperature T_{c} in monolayers of FeSe grown on several oxide substrates has opened a new route to high-T_{c} superconductivity through interface engineering. One proposal for the origin of the observed enhancement is an electronphonon (e-ph) interaction across the interface that peaked at small momentum transfers. In this paper, we examine the implications of such a coupling on the phononic properties of the system. We show that a strong forward scattering leads to a sizable broadening of phonon lineshape, which may result in charge instabilities at long-wavelengths. However, we further find that the inclusion of Coulombic screening significantly reduces the phonon broadening. Our results show that one might not expect anomalously broad phonon linewidths in the FeSe interface systems, despite the fact that the e-ph interaction has a strong peak in the forward scattering (small \\bfq ) direction.
Directory of Open Access Journals (Sweden)
Andrés Gené-Sampedro
2012-04-01
Full Text Available A 41-year-old patient with visual disturbances after an ocular trauma in right eye three years before was carefully analyzed and discussed. No corneal or intraocular sequelae were present. Only a significant anisocoria could be observed. Right eye (RE achieved a best spectacle-corrected visual acuity (BSCVA of 0.05 LogMAR with a refraction of +0.50 sphere and −1.25 cylinder. Left eye (LE achieved a BSCVA of 0.0 LogMAR with a refraction of +0.75 sphere and −1.00 cylinder. In photopic conditions pupil diameter was 4.96 mm for RE and 3.02 mm for LE whereas in scotopic conditions, these values were 7.45 mm and 6.71 mm, respectively. More significant levels of higher-order corneal and ocular aberrations were found in RE for the same pupil size. In addition, the scattering index (OSI was 3.8 in RE and 1.0 in LE (4-mm pupil. In conclusion, anisocoria can lead to relevant visual disturbances if significant interocular differences in ocular aberrations and scattering are present.
Aggarwal, Roshan L; Farrar, Lewis W; Greeneltch, Nathan G; Van Duyne, Richard P; Polla, Dennis L
2013-02-01
The surface-enhanced coherent anti-Stokes Raman scattering (SECARS) from a self-assembled monolayer (SAM) of benzenethiol on a silver-coated surface-enhanced Raman scattering (SERS) substrate has been measured for the 1574 cm(-1) SERS mode. A value of 9.6 ± 1.7×10(-14) W was determined for the resonant component of the SECARS signal using 17.8 mW of 784.9 nm pump laser power and 7.1 mW of 895.5 nm Stokes laser power; the pump and Stokes lasers were polarized parallel to each other but perpendicular to the grooves of the diffraction grating in the spectrometer. The measured value of resonant component of the SECARS signal is in agreement with the calculated value of 9.3×10(-14) W using the measured value of 8.7 ± 0.5 cm(-1) for the SERS linewidth Γ (full width at half-maximum) and the value of 5.7 ± 1.4×10(-7) for the product of the Raman cross section σSERS and the surface concentration Ns of the benzenethiol SAM. The xxxx component of the resonant part of the third-order nonlinear optical susceptibility |3 χxxxx((3)R)| for the 1574 cm(-1) SERS mode has been determined to be 4.3 ± 1.1×10(-5) cm·g(-1)·s(2). The SERS enhancement factor for the 1574 cm(-1) mode was determined to be 3.6 ± 0.9×10(7) using the value of 1.8×10(15) molecules/cm(2) for Ns.
International Nuclear Information System (INIS)
Sugano, M; Yoshida, Y; Hojo, M; Shikimachi, K; Hirano, N; Nagaya, S
2008-01-01
Tensile fatigue tests were carried out at 77 K for YBCO-coated conductors fabricated by metal-organic chemical vapor deposition (MOCVD). The S-N relationship, variation of critical current (I c ) during cyclic loading and microscopic fatigue damage were investigated. Fatigue strength at 10 6 cycles was evaluated to be σ max = 1300 MPa and 890 MPa under the stress ratios of 0.5 and 0.1. Two different mechanisms of fatigue damage, depending on the number of stress cycles to failure, were observed. In one of the fracture mechanisms, fatigue behavior is characterized by overall fracture which occurs at 10 4 -10 5 cycles. For these specimens, I c after unloading does not degrade before overall fracture. Although only shallow slip bands were found at the Ag surface, fatigue cracks were found on the Hastelloy C-276 surface of the fractured specimen. These results suggest that overall fracture due to cyclic stress was caused by fatigue of the Hastelloy substrate. In the other fracture mechanism, even though overall fracture did not occur at 10 6 cycles, a slight decrease of I c was detected after 10 5 cycles. No fatigue crack was found on the Hastelloy surface, while deep slip bands corresponding to the initial stage of fatigue crack were observed on the Ag surface. From these results, we concluded that I c degradation at a high cycle number is attributed to the fatigue of the Ag stabilizing layer
International Nuclear Information System (INIS)
Wright, H.L.; Meason, J.L.; Wolf, M.; Harvey, J.T.
1976-01-01
Measurements have been performed on the perturbing effect of a number of scattering materials by the 'free-field' neutron leakage spectrum from a Godiva Type Critical Assembly (White Sands Missile Range Fast Burst Reactor). The results of these measurements are interpreted in relation to some of the general parameters characterizing a neutron environment, namely, the average neutron energy >10 KeV, the spectral index and the hardness parameter. Three neutron spectrum measurements have been performed, each under different experimental configurations of scattering materials. Results from these measurements show the following with relation to the spectral index: (1) The neutron environment on the core surface and at 12-inches from the core surface (free-field) yield a spectral index of 6.8, (2) The neutron environment behind a 4.75-inch Plexiglas plate yield 4.6 for the spectral index and (3) The neutron environment behind a 2-inch aluminum plate yield 6.7 for the spectral index. It is concluded that the core surface and the 12-inch from core surface neutron environment are identical with the 'free-field' neutron environment at 20-inches when considering only those neutrons with energy >10 KeV. On the other hand, it appears that the 4.75 inches of Plexiglas severely perturbs the 'free-field' neutron environment, i.e., a much harder neutron spectrum >10 KeV. In the situation where 2-inches of aluminum is used as the perturbing medium, essentially no change in the neutron spectrum >10 KeV is noted
2009-07-07
inversion technique that is based on different weights for relatively high frequency waveform modeling of Pnl and relatively long period surface waves (Tan...et al., 2006). Pnl and surface waves are also allowed to shift in time to take into account of uncertainties in velocity structure. Joint...inversion of Pnl and surface waves provides better constraints on focal depth as well as source mechanisms. The pure strike-slip mechanism of the earthquake
On the mechanical stress of Zr, Zry, and other materials due to the formation of oxide layers
International Nuclear Information System (INIS)
Hofmann, P.
1977-06-01
Several mechanisms are indicated which during oxidation of sheets, tubes, and cylinders of pure metals and alloys might lead to plastic deformation of the remaining uncorroded cross section. Some experimental methods are described which allow evaluation of stresses occurring in oxide layers. The main reason for the creep deformation of flat and tubular specimens made of Zr and Zr alloys lies in the stresses that arise from volume increase due to the growth of oxide layers. Plastic deformations of the sheet metal specimens can be up to 100% and are anisotropic. In tubular specimens the changes in geometry (axial, radial) are much smaller in the course of oxidation and attain 2% at the maximum for Zr- or Zry-tubes and go up to 10% for Ta-tubes when no differential pressure is applied simultaneously. (orig.) [de
Nagata, Yuka; Muro, Yoshinao; Todokoro, Kazuo
1997-01-01
Megakaryocytes undergo a unique differentiation program, becoming polyploid through repeated cycles of DNA synthesis without concomitant cell division. However, the mechanism underlying this polyploidization remains totally unknown. It has been postulated that polyploidization is due to a skipping of mitosis after each round of DNA replication. We carried out immunohistochemical studies on mouse bone marrow megakaryocytes during thrombopoietin- induced polyploidization and found that during this process megakaryocytes indeed enter mitosis and progress through normal prophase, prometaphase, metaphase, and up to anaphase A, but not to anaphase B, telophase, or cytokinesis. It was clearly observed that multiple spindle poles were formed as the polyploid megakaryocytes entered mitosis; the nuclear membrane broke down during prophase; the sister chromatids were aligned on a multifaced plate, and the centrosomes were symmetrically located on either side of each face of the plate at metaphase; and a set of sister chromatids moved into the multiple centrosomes during anaphase A. We further noted that the pair of spindle poles in anaphase were located in close proximity to each other, probably because of the lack of outward movement of spindle poles during anaphase B. Thus, the reassembling nuclear envelope may enclose all the sister chromatids in a single nucleus at anaphase and then skip telophase and cytokinesis. These observations clearly indicate that polyploidization of megakaryocytes is not simply due to a skipping of mitosis, and that the megakaryocytes must have a unique regulatory mechanism in anaphase, e.g., factors regulating anaphase such as microtubule motor proteins might be involved in this polyploidization process. PMID:9334347
Reish, O; Townsend, D; Berry, S A; Tsai, M Y; King, R A
1995-01-01
Deficiency of cystathionine beta-synthase (CBS) is a genetic disorder of transsulfuration resulting in elevated plasma homocyst(e)ine and methionine and decreased cysteine. Affected patients have multisystem involvement, which may include light skin and hair. Reversible hypopigmentation in treated homocystinuric patients has been infrequently reported, and the mechanism is undefined. Two CBS-deficient homocystinuric patients manifested darkening of their hypopigmented hair following treatment that decreased plasma homocyst(e)ine. We hypothesized that homocyst(e)ine inhibits tyrosinase, the major pigment enzyme. The activity of tyrosinase extracted from pigmented human melanoma cells (MNT-1) that were grown in the presence of homocysteine was reduced in comparison to that extracted from cells grown without homocysteine. Copper sulfate restored homocyst(e)ine-inhibited tyrosinase activity when added to the culture cell media at a proportion of 1.25 mol of copper sulfate per 1 mol of DL-homocysteine. Holo-tyrosinase activity was inhibited by adding DL-homocysteine to the assay reaction mixture, and the addition of copper sulfate to the reaction mixture prevented this inhibition. Other tested compounds, L-cystine and betaine did not affect tyrosinase activity. Our data suggest that reversible hypopigmentation in homocystinuria is the result of tyrosinase inhibition by homocyst(e)ine and that the probable mechanism of this inhibition is the interaction of homocyst(e)ine with copper at the active site of tyrosinase. Images Figure 1 PMID:7611281
Gunathilaka, Mahesh Lakmal; Niriella, Madunil Anuk; Luke, Nathasha Vihangi; Piyarathna, Chathura Lakmal; Siriwardena, Rohan Chaminda; De Silva, Arjuna Priyadarshin; de Silva, Hithanadura Janaka
2017-07-03
Hydrocarbon-induced occupational liver injury is a well-known clinical entity among petroleum industry workers. There are many types of hydrocarbon exposure, with inhalation being the most common. Hydrocarbon-induced occupational liver injury is a rarely suspected and commonly missed etiological agent for liver injury. We report a case of a non-petroleum industry worker with chronic liver disease secondary to hydrocarbon-induced occupational liver injury caused by chronic low-grade hydrocarbon ingestion due to occupational malpractice. A 23-year-old Sri Lankan man who was a motor mechanic presented to our hospital with decompensated cirrhosis. He had been chronically exposed to gasoline via inadvertent ingestion due to occupational malpractice. He used to remove gasoline from carburetors by sucking and failed to practice mouth washing thereafter. On evaluation, he had histologically proven established cirrhosis. A comprehensive history and workup ruled out other nonoccupational etiologies for cirrhosis. The patient's long-term occupational gasoline exposure and clinical course led us to a diagnosis of hydrocarbon-induced occupational liver injury leading to decompensated cirrhosis. Hydrocarbon-induced occupational liver injury should be considered as a cause when evaluating a patient with liver injury with possible exposure in relevant occupations.
International Nuclear Information System (INIS)
Bayat, Mehdi; Saleem, M.; Sahari, B.B.; Hamouda, A.M.S.; Mahdi, E.
2009-01-01
Rotating disks have many applications in the aerospace industry such as gas turbines and gears. These disks normally work under thermo mechanical loads. Minimizing the weight of such components can help reduce the overall payload in aerospace industry. For this purpose, a rotating functionally graded (FG) disk with variable thickness under a steady temperature field is considered in this paper. Thermo elastic solutions and the weight of the disk are related to the material grading index and the geometry of the disk. It is found that a disk with parabolic or hyperbolic convergent thickness profile has smaller stresses and displacements compared to a uniform thickness disk. Maximum radial stress due to centrifugal load in the solid disk with parabolic thickness profile may not be at the center unlike uniform thickness disk. Functionally graded disk with variable thickness has smaller stresses due to thermal load compared to those with uniform thickness. It is seen that for a given value of grading index, the FG disk having concave thickness profile is the lightest in weight whereas the FG disk with uniform thickness profile is the heaviest. Also for any given thickness profile, the weight of the FG disk lies in between the weights of the all-metal and the all-ceramic disks.
Energy Technology Data Exchange (ETDEWEB)
Malpartida Moya, John E.; Sota, Giancarlo Massucco de la; Seri, Walter [Compania Operadora de Gas del Amazonas, Lima (Peru)
2009-07-01
Every pipeline integrity management system evaluates and controls various threats. On pipelines which have particular characteristics as it is the case of the Andean pipelines and pipelines crossing jungles, one of the main threats are the external forces. Even, this threat causes a greater number of failures than other threats like corrosion or the third part damage. Facing this situation, the pipeline integrity management system of TgP has achieved an important development in the use and suitable handling of the information provided by diverse techniques of pipeline mechanical inspection and geotechnical inspection of the right-of-way (ROW). This document presents our methodology, which interrelate information of the in-line inspection, information of geotechnical inspections of the ROW, instrumentation (Strain Gages), topographic monitoring, among others. All this information is supported in a Geographic Information System (GIS) which allows us to integrate the information. By means of the pipeline integrity management system we control potential risks due to external forces, we have been able to act before events become critical, with no occurrence of failures. This system allows us simultaneously to optimize efforts and preserve the mechanical integrity of our pipelines, not producing neither personal nor environmental nor economical affectation. (author)
Energy Technology Data Exchange (ETDEWEB)
Yassi, Yousef; hashemloo, Safar [Iranian Research Organization for Science and Technology (IROST), No. 29 Forssat St., Enghelaab Ave., Tehran (Iran)
2010-10-15
Agnew turbine is an axial micro hydro of Kaplan type, with its main shaft subtending 45 to the line of horizon. Due to governmental power generating programs for limited hydro potentials in Iran and on the basis of a joint project between the University of Glasgow and the Iranian Research Organization for Science and Technology (IROST), the turbine was developed to operate under low heads and limited flow potentials in Iran. However the turbine was originally designed to operate without any guide vanes and test results showed that the turbine achieved an efficiency of 62% at its best point of performance. Later a modified Agnew turbine, consisting of a guide blades mechanism was designed and manufactured, at (IROST). The mechanism was so designed that it was also used as a second support for the turbine's main shaft. The standard turbine tests proved that; the modified version of the Agnew turbine had 23% higher efficiency at its best performance point; compared to the original design. Then the effects of the improvements on the turbine were studied on the performance of the turbine at part loads. However, efficiency improvements were observed under all part load conditions. (author)
International Nuclear Information System (INIS)
Yassi, Yousef; Hashemloo, Safar
2010-01-01
Agnew turbine is an axial micro hydro of Kaplan type, with its main shaft subtending 45 deg. to the line of horizon. Due to governmental power generating programs for limited hydro potentials in Iran and on the basis of a joint project between the University of Glasgow and the Iranian Research Organization for Science and Technology (IROST), the turbine was developed to operate under low heads and limited flow potentials in Iran. However the turbine was originally designed to operate without any guide vanes and test results showed that the turbine achieved an efficiency of 62% at its best point of performance. Later a modified Agnew turbine, consisting of a guide blades mechanism was designed and manufactured, at (IROST). The mechanism was so designed that it was also used as a second support for the turbine's main shaft. The standard turbine tests proved that; the modified version of the Agnew turbine had 23% higher efficiency at its best performance point; compared to the original design. Then the effects of the improvements on the turbine were studied on the performance of the turbine at part loads. However, efficiency improvements were observed under all part load conditions.
Lunn, R. J.; Kinali, M.; Pytharouli, S.; Shipton, Z.; Stillings, M.; Lord, R.
2016-12-01
The drainage and refilling of a surface water reservoir beside the Grimsel Test Site (GTS) underground rock laboratory in Switzerland, has provided a unique opportunity to study in-situ rock mechanical, hydraulic and chemical interactions under large-scale stress changes. The reservoir was drained in October/November 2014 to enable dam maintenance and extension of the regional hydropower tunnel system. Reservoir drainage will have caused rapid unloading of the surrounding rock mass. The GTS sits 37m below the top of the reservoir and 200-600m away laterally within the mountainside on the eastern bank of the reservoir. Gradual refilling of the reservoir, via natural snowmelt and runoff, commenced in February 2015. As part of the European LASMO Project, researchers at Strathclyde, funded by Radioactive Waste Management Ltd., have been investigating mechanical-chemical-hydraulic coupling within the rock mass as an analogue for glacial unloading and loading of a future Geological Disposal Facility. We have deployed three 3-component and 6 single-component micro-seismometers within the GTS and surrounding hydropower tunnel network. In parallel, we have implemented a groundwater sampling programme, using boreholes within the GTS, for temporal determination of geochemistry and flow rate. Preliminary data analyses show geochemical anomalies during unloading, as well as detection of microseismic events. The signal-to-noise ratio of the micro-seismic data is extremely poor. Noise amplitude, and frequency content, variy throughout each day, between days, and from month-to-month on a highly unpredictable basis. This is probably due to the multitude of hydropower turbines and pump-storage systems within the surrounding mountains. To discriminate micro-seismic events, we have developed a new methodology for characterizing background noise within the seismic signal and combined this with cross-correlations techniques generally applied in microseismic analysis of hydraulic
Rahman, Masoud; Tajabadi, Fariba; Shooshtari, Leyla; Taghavinia, Nima
2011-04-04
Hollow structures show both light scattering and light trapping, which makes them promising for dye-sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO(2) fibers are prepared by layer-by-layer (LbL) self-assembly deposition of TiO(2) nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO(2) dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes (poly(diallyldimethylammonium chloride), PDDA). Decreasing the molecular weight of the polyelectrolyte results in more deposition of nanoparticles in each dip cycle with narrower pore size distribution. Fibers prepared by the deposition of crystalline TiO(2) nanoparticles show higher surface area and higher pore volume than amorphous nanoparticles. Scattering coefficients and backscattering properties of fibers are investigated and compared with those of commercial P25 nanoparticles. Composite P25-fiber films are electrophoretically deposited and employed as the photoanode in DSSC. Photoelectrochemical measurements showed an increase of around 50% in conversion efficiency. By employing the intensity-modulated photovoltage and photocurrent spectroscopy methods, it is shown that the performance improvement due to addition of fibers is mostly due to the increase in light-harvesting efficiency. The high surface area due to the nanoparticulate structure and strong light harvesting due to the hollow structure make these fibers promising scatterers in DSSCs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Jahn, H.
1980-01-01
Absolute values of secondary energy-dependent inelastic neutron scattering cross sections can be calculated either with the master equation pre-equilibrium formalism of Cline and Blann or with Blann's more recent geometry-dependent hybrid model. The master equation formalism was used at Dubna and Dresden to reproduce experimental results for 14 MeV incident energy. The geometry-dependent hybrid model was used at Karlsruhe to cover for a number of materials the whole range from 5 to 14 MeV incident energy and to reproduce smoothed experimental spectra at 7.45 and 14 MeV. Only the geometry-dependent hybrid model accounts for scattering in the diffuse nuclear surface and thus for a certain average over the direct interaction. It is also free of any fit parameters other than those of the usual optical model. The master equation calculations, on the other hand, are based on nucleon-nucleon scattering cross sections inserted into the high-energy approximation of Kikuchi and Kawai for the intranuclear transition rate. Other approaches require either mass- or energy-dependent or more global fit parameters for a satisfactory reproduction of experimental results, but a genuine prediction of the incident-energy dependence of the inelastic neutron cross section, especially below 14 MeV, is needed for transport and shielding calculations for instance in connection with fusion reactor design studies. (author)
Role of electron-electron scattering on spin transport in single layer graphene
Directory of Open Access Journals (Sweden)
Bahniman Ghosh
2014-01-01
Full Text Available In this work, the effect of electron-electron scattering on spin transport in single layer graphene is studied using semi-classical Monte Carlo simulation. The D’yakonov-P’erel mechanism is considered for spin relaxation. It is found that electron-electron scattering causes spin relaxation length to decrease by 35% at 300 K. The reason for this decrease in spin relaxation length is that the ensemble spin is modified upon an e-e collision and also e-e scattering rate is greater than phonon scattering rate at room temperature, which causes change in spin relaxation profile due to electron-electron scattering.
International Nuclear Information System (INIS)
Fernandez, L; Fernandez, G.E; Bertolino, G; Meyer, G
2001-01-01
The study of mechanical properties degradation of zirconium alloys due to hydrides assumes fundamental importance in the nuclear industry.During normal nuclear reactors operation, structural parts absorbed hydrogen generated from radiolysis of water, causing detrimental effects on mechanical properties.As a consequence, these materials are easily cracked in the presence of mechanical solicitation due to loss of ductility of the hydride-phase.The presence of cracks indicates fracture mechanic as the most suitable methodology in the study of mechanical properties degradation.In this work we used the crack tip opening displacement (CTOD) criteria to evaluate the detrimental effects on mechanical properties with the observation in SEM of crack propagation.The samples used were SEN (B) of Zry-4 and cathodic homogenous charged with hydrogen concentrations lower than 400 ppm
Energy Technology Data Exchange (ETDEWEB)
Schumacher, Jan W
2010-10-15
An analysis of the expected sensitivity of the ATLAS experiment at the Large Hadron Collider at CERN to alternative mechanisms of electroweak symmetry breaking in the dileptonic vector boson scattering channel is presented. With the generalized K-Matrix model of vector boson scattering recently implemented in the event generator Whizard, several additional resonances are investigated. Whizard is validated for ATLAS use and an interface for the Les Houches event format is adapted for the ATLAS software Athena. Systematic model and statistical Monte Carlo uncertainties are reduced with a signal definition using events reweighted in the couplings g of the new resonances. Angular correlations conserved by Whizard are used in the event selection. A multivariate analyzer is trained to take into account correlations between the selection variables and thereby to improve the sensitivity compared to cut analyses. The statistical analysis is implemented with a profile likelihood method taking into account systematic uncertainties and statistical uncertainties from Monte Carlo. Ensemble tests are performed to assure the applicability of the method. Expected discovery significances and coupling limits for new additional resonances in vector boson scattering are determined. (orig.)
Enhanced J/psi suppression due to gluon depletion
Hwa, R. C.; Pisut, J.; Pisutova, N.
1997-01-01
The nonlinear effect of gluon depletion in the collision of large nuclei can be large. It is due to multiple scatterings among comoving partons initiated by primary scattering of partons in the colliding nuclei. The effect can give rise to substantial suppression of $J/\\psi$ production in very large nuclei, even if the linear depletion effect is insignificant for the collisions of nuclei of smaller sizes. This mechanism offers a natural explanation of the enhanced suppression in the Pb-Pb dat...
International Nuclear Information System (INIS)
Yano, M.; Manabe, A.; Shoji, T.; Kato, A.; Ono, K.; Harada, M.; Kohlbrecher, J.
2014-01-01
The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd 2 Fe 14 B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the Teubner–Stray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains
Dapor, Maurizio
2018-03-29
Quantum information theory deals with quantum noise in order to protect physical quantum bits (qubits) from its effects. A single electron is an emblematic example of a qubit, and today it is possible to experimentally produce polarized ensembles of electrons. In this paper, the theory of the polarization of electron beams elastically scattered by atoms is briefly summarized. Then the POLARe program suite, a set of computer programs aimed at the calculation of the spin-polarization parameters of electron beams elastically interacting with atomic targets, is described. Selected results of the program concerning Ar, Kr, and Xe atoms are presented together with the comparison with experimental data about the Sherman function for low kinetic energy of the incident electrons (1.5eV-350eV). It is demonstrated that the quantum-relativistic theory of the polarization of electron beams elastically scattered by atoms is in good agreement with experimental data down to energies smaller than a few eV.
Mahdavi, Sahel; Maghsoudi, Yasser; Amani, Meisam
2017-07-01
Environmental conditions have considerable effects on synthetic aperture radar (SAR) imagery. Therefore, assessing these effects is important for obtaining accurate and reliable results. In this study, three series of RADARSAT-2 SAR images were evaluated. In each of these series, the sensor configuration was fixed, but the environmental conditions differed. The effects of variable environmental conditions were also investigated on co- and cross-polarized backscattering coefficients, Freeman-Durden scattering contributions, and the pedestal height in different classes of a forest area in Ottawa, Ontario. It was observed that the backscattering coefficient of wet snow was up to 2 dB more than that of dry snow. The absence of snow also caused a decrease of up to 3 dB in the surface scattering of ground and up to 5 dB in that of trees. In addition, the backscatter coefficients of ground vegetation, hardwood species, and softwood species were more similar at temperatures below 0°C than those at temperatures above 0°C. Moreover, the pedestal height was generally greater at temperatures above 0°C than at temperatures below 0°C. Finally, the highest class separability was observed when the temperature was at or above 0°C and there was no snow on the ground or trees.
Exchange interaction in scattering on the bound state
International Nuclear Information System (INIS)
Arkhipov, A.A.; Savrin, V.I.
1975-01-01
In the framework of the one-time formulation of three-body problem in quantum field theory, the problem of scattering on the bound state is considered for the case when one of the incident particles is identical to one of the particles of the target. It is shown that due to the identical nature of these particles the exchange interaction takes place which can be connected with the mechanism of scattering on the bound state with the rearrangement
International Nuclear Information System (INIS)
Shu, D; Stoupin, S; Khachatryan, R; Goetze, K A; Roberts, T; Shvyd'ko, Y; Mundboth, K; Collins, S
2013-01-01
There are many scientific applications, especially involving topics related to the equilibrium atomic-scale dynamics of condensed matter, that require both a narrower and a steeper resolution function and access to a broader dynamic range than are currently available. To meet these important scientific needs, a prototype of a novel ultrahigh-resolution inelastic x-ray scattering spectrometer system has been designed and constructed at undulator-based beamline 30-ID at the Advanced Photon Source, Argonne National Laboratory. This prototype is designed to meet challenging mechanical and optical specifications for performing so-called CDFDW angular-dispersive x-ray crystal optics, which include a central ultra-thin CFW crystal and a pair of dispersing elements. The abbreviation CDFDW stands for: C – collimating crystal, D – dispersing-element crystal (two D-crystals are used in each CDFDW), F – anomalous transmission filter, and W – wavelength-selector crystal [1]. The mechanical design of the ultrahigh-resolution inelastic x-ray scattering spectrometer, as well as the preliminary test results of its precision positioning performance are presented in this paper.
Decoherence due to elastic rayleigh scattering
CSIR Research Space (South Africa)
Uys, H
2010-11-01
Full Text Available . acknowledges support from Georgia Tech and IARPA. D.M. is supported by NSF. This work was supported by the DARPA OLE program and by IARPA. This manuscript is the contribution of NIST and is not subject to U.S. copyright. *huys@csir.co.za †john...
Sadeghzadeh, S.
2017-11-01
Two-dimensional (2D) materials have recently attracted a great attraction. This paper provides a detailed discussion on the rupture mechanisms of different allotropes of boron. As a new 2D material by using a reactive molecular dynamics model, probable types of rupture for borophene sheets were studied, among which two dominant mechanisms were observed: creation of the cracks and formation of nanopores. The results obtained are compared to those for graphene and h-BN nano sheets, although the rupture mechanism was completely different from the graphene and h-BN sheets. The simulations suggested that borophene might remain more stable against external mechanical loads than graphene and BN sheets. Cracking leads to larger strain along the loading direction, whereas the creation of local pores spends the imposed energy for breaking the internal bonds and so flowing the external energy into the various bonds increases the number of pores. For the armchair-types, cracking is a dominant mechanism while for the zigzag-type the common mechanism is the creation of nanopores. These interesting results may help to design a new class of semiconductors that remain stable even when are sustaining uncontrollable external stresses.
International Nuclear Information System (INIS)
Andrikopoulos, K S; Yannopoulos, S N; Voyiatzis, G A; Kolobov, A V; Ribes, M; Tominaga, J
2006-01-01
We report on an inelastic (Raman) light scattering study of the local structure of amorphous GeTe (a-GeTe) films. A detailed analysis of the temperature-reduced Raman spectra has shown that appreciable structural changes occur as a function of temperature. These changes involve modifications of atomic arrangements such as to facilitate the rapid amorphous to crystal transformation, which is the major advantage of phase-change materials used in optical data storage media. A particular structural model, supported by polarization analysis, is proposed which is compatible with the experimental data as regards both the structure of a-GeTe and the crystallization transition. The remarkable difference between the Raman spectrum of the crystal and the glass can thus naturally be accounted for
International Nuclear Information System (INIS)
Reiter, G F; Deb, Aniruddha
2014-01-01
Neutron Compton scattering(NCS) measurements of the momentum distribution of light ions using the Vesuvio instrument at ISIS provide a sensitive local probe of the environment of those ions. NCS measurements of the proton momentum distribution in bulk water show only small deviations from the usual picture of water as a collection of molecules, with the protons covalently bonded to an oxygen and interacting weakly, primarily electrostatically, with nearby molecules. However, a series of measurements of the proton momentum distribution in carbon nanotubes, xerogel, and Nafion show that the proton delocalizes over distances of 0.2-0.3Å when water is confined on the scale of 20Å. This delocalization must be the result of changes in the Born-Oppenheimer surface for the protons, which would imply that there are large deviations in the electron distribution from that of a collection of weakly interacting molecules. This has been observed at Spring-8 using x-ray Compton scattering. The observed deviation in the valence electron momentum distribution from that of bulk water is more than an order of magnitude larger than the change observed in bulk water as the water is heated from just above melting to just below boiling. We conclude that the protons and electrons in nano-confined water are in a qualitatively different ground state from that of bulk water. Since the properties of this state persist at room temperature, and the confinement distance necessary to observe it is comparable to the distance between the elements of biological cells, this state presumably plays a role in the functioning of those cells
Jensen, Craig C.; Lydersen, Tore; Johnson, Paul R.; Weiss, Shannon R.; Marconi, Michael R.; Cleave, Mary L.; Weber, Patricia
2012-01-01
Background: Using mechanical restraints to protect a person who engaged in dangerous self-injury was decreased by manipulation of an establishing operation involving the client choosing the staff person who would work with her. Materials and Methods: The client was a 28-year-old woman diagnosed with autism, bipolar disorder, static cerebral…
Texture and magnetic property evolution of non-oriented Fe–Si steel due to mechanical cutting
International Nuclear Information System (INIS)
Xiong, Xuesong; Hu, Shubing; Hu, Ke; Zeng, Siqi
2016-01-01
Microstructures and textures as well as magnetic properties of a non-oriented Fe–Si steel with thickness of 0.5 mm and medium silicon content after mechanical cutting were investigated. The results from electron backscatter diffraction (EBSD) analysis indicated that in the cut edge zone, mechanical cutting resulted in a significant increase in low-angle boundaries (LAGBs, 2°≤θ≤15°) and dislocation densities from both the upper surface (in the shear zone) and the lower surface (in the fracture zone). Mechanical cutting also led to a visible change in textures, such as, intensity decrease of λ fiber (<001>∥normal direction [ND]) and γ fiber (<111>∥ND) components from the upper surface as well as Goss texture ({110}<001>texture) from the lower surface. Microstructure and texture changes from the upper surface seem to be more obvious than these from the lower surface. The results from single sheet testing showed mechanical cutting induced an evident deterioration in magnetic properties and a clear change in hysteresis loop of the steel, and these variations became more obvious with increasing cutting length per mass from 0.86 m/kg to 2.57 m/kg. The largest increment of iron loss reached to 18.45% and 21.76% when the flux density was at 1.0 T and 1.5 T, respectively. The possible main reasons for the changes in magnetic properties and hysteresis loops were discussed in terms of the texture factor TF or residual stress. - Highlights: • Microstructures and textures in the cut edge zone were characterized via EBSD. • Microstructure and texture differences between different surfaces were analyzed. • Quantitative effect of mechanical cutting on magnetic properties was investigated.
Directory of Open Access Journals (Sweden)
Joergen L. Jensen
2016-01-01
Full Text Available In partially anchored timber frame shear walls, hold-down devices are not provided; hence the uplift forces are transferred by the fasteners of the sheathing-to-framing joints into the bottom rail and via anchor bolts from the bottom rail into the foundation. Since the force in the anchor bolts and the sheathing-to-framing joints do not act in the same vertical plane, the bottom rail is subjected to tensile stresses perpendicular to the grain and splitting of the bottom rail may occur. This paper presents simple analytical models based on fracture mechanics for the analysis of such bottom rails. An existing model is reviewed and several alternative models are derived and compared qualitatively and with experimental data. It is concluded that several of the fracture mechanics models lead to failure load predictions which seem in sufficiently good agreement with the experimental results to justify their application in practical design.
2014-12-31
frequency A/C motor. The drive chain is configured such that a belt rotates an eccentric disk and a momentum fly wheel to minimize the unsteady...b) thrust bearing for pitch oscillation. Connection Bar Movement Lever Arm Fly Wheel Eccentric Disk V-Belt 5-hp A/C Motor Flow Pulley diameter... eccentric disk and drive mechanism, and (b) thrust bearing for pitch oscillation
Energy Technology Data Exchange (ETDEWEB)
Sun, Z. [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); Retraint, D., E-mail: delphine.retraint@utt.fr [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); Baudin, T.; Helbert, A.L.; Brisset, F. [ICMMO, Univ Paris-Sud, Université Paris-Saclay, UMR CNRS 8182, 91405 Orsay Cedex (France); Chemkhi, M.; Zhou, J. [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); Kanouté, P. [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); ONERA, The French Aerospace Lab, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France)
2017-02-15
Electron Backscatter Diffraction technique is used to characterize the microstructure of 316L steel generated by Surface Mechanical Attrition Treatment (SMAT) before and after low cycle fatigue tests. A grain size gradient is generated from the top surface to the interior of the samples after SMAT so that three main regions can be distinguished below the treated surface: (i) the ultra-fine grain area within 5 μm under the top surface with preferably oriented grains, (ii) the intermediate area where the original grains are partially transformed, and (iii) the edge periphery area where the original grains are just mechanically deformed with the presence of plastic slips. Fatigue tests show that cyclic loading does not change the grain orientation spread and does not activate any plastic slip in the ultra-fine grain top surface area induced by SMAT. On the opposite, in the plastically SMAT affected region including the intermediate area and the edge periphery area, new slip systems are activated by low cycle fatigue while the grain orientation spread is increased. These results represent a first very interesting step towards the characterization and understanding of mechanical mechanisms involved during the fatigue of a grain size gradient material. - Highlights: •LCF tests are carried out on specimens processed by SMAT. •EBSD is used to investigate microstructural changes induced by LCF. •A grain size gradient is generated by SMAT from surface to the bulk of the fatigue samples. •New slip systems are activated by LCF and GOS is increased in plastically deformed region. •However, these phenomena are not observed in the top surface ultra-fine grain area.
International Nuclear Information System (INIS)
Sun, Z.; Retraint, D.; Baudin, T.; Helbert, A.L.; Brisset, F.; Chemkhi, M.; Zhou, J.; Kanouté, P.
2017-01-01
Electron Backscatter Diffraction technique is used to characterize the microstructure of 316L steel generated by Surface Mechanical Attrition Treatment (SMAT) before and after low cycle fatigue tests. A grain size gradient is generated from the top surface to the interior of the samples after SMAT so that three main regions can be distinguished below the treated surface: (i) the ultra-fine grain area within 5 μm under the top surface with preferably oriented grains, (ii) the intermediate area where the original grains are partially transformed, and (iii) the edge periphery area where the original grains are just mechanically deformed with the presence of plastic slips. Fatigue tests show that cyclic loading does not change the grain orientation spread and does not activate any plastic slip in the ultra-fine grain top surface area induced by SMAT. On the opposite, in the plastically SMAT affected region including the intermediate area and the edge periphery area, new slip systems are activated by low cycle fatigue while the grain orientation spread is increased. These results represent a first very interesting step towards the characterization and understanding of mechanical mechanisms involved during the fatigue of a grain size gradient material. - Highlights: •LCF tests are carried out on specimens processed by SMAT. •EBSD is used to investigate microstructural changes induced by LCF. •A grain size gradient is generated by SMAT from surface to the bulk of the fatigue samples. •New slip systems are activated by LCF and GOS is increased in plastically deformed region. •However, these phenomena are not observed in the top surface ultra-fine grain area.
Energy Technology Data Exchange (ETDEWEB)
Torok, J
1995-03-01
The concrete roof of a near-surface radioactive waste repository is the principle protection against water infiltration and intrusion. The following potential roof failure mechanism is examined: carbon dioxide generated by the biodegradation of organic materials in the repository initiates corrosion of reinforcing steel embedded in the concrete roof. Because the bottom surface of the roof is mostly under tension, it is susceptible to cracking. The migration path for carbon dioxide is through cracks in the concrete between the bottom of the roof and the reinforcing bars. Carbonate corrosion of the reinforcing bars may result in concrete spalling, more extensive rebar corrosion and ultimately structural failure. Attention is brought to this failure mechanism because it has generally been overlooked in repository performance assessments. Literature relevant to the above failure is reviewed. Prerequisites for rebar corrosion are the presence of carbon dioxide and oxygen in the repository gas, high relative humidity and through-cracks in the concrete. High carbon dioxide concentrations and relative humidity are expected in the repository. The oxygen concentration in the repository is expected to be very low, and that is expected to minimize rebar corrosion rates. Cracks are likely to form in locations with high tensile stresses. Healing of the cracks could be a mitigating factor, but based on our analysis, it can not be relied on. To minimize the potential of this failure mechanism occurring with the Intrusion Resistant Underground Structure (IRUS), Canada`s proposed near-surface repository, carbon dioxide from the repository gas will be absorbed by the reactive, porous concrete placed between the waste and the roof. (author). 4 refs.
International Nuclear Information System (INIS)
Torok, J.
1995-03-01
The concrete roof of a near-surface radioactive waste repository is the principle protection against water infiltration and intrusion. The following potential roof failure mechanism is examined: carbon dioxide generated by the biodegradation of organic materials in the repository initiates corrosion of reinforcing steel embedded in the concrete roof. Because the bottom surface of the roof is mostly under tension, it is susceptible to cracking. The migration path for carbon dioxide is through cracks in the concrete between the bottom of the roof and the reinforcing bars. Carbonate corrosion of the reinforcing bars may result in concrete spalling, more extensive rebar corrosion and ultimately structural failure. Attention is brought to this failure mechanism because it has generally been overlooked in repository performance assessments. Literature relevant to the above failure is reviewed. Prerequisites for rebar corrosion are the presence of carbon dioxide and oxygen in the repository gas, high relative humidity and through-cracks in the concrete. High carbon dioxide concentrations and relative humidity are expected in the repository. The oxygen concentration in the repository is expected to be very low, and that is expected to minimize rebar corrosion rates. Cracks are likely to form in locations with high tensile stresses. Healing of the cracks could be a mitigating factor, but based on our analysis, it can not be relied on. To minimize the potential of this failure mechanism occurring with the Intrusion Resistant Underground Structure (IRUS), Canada's proposed near-surface repository, carbon dioxide from the repository gas will be absorbed by the reactive, porous concrete placed between the waste and the roof. (author). 4 refs
International Nuclear Information System (INIS)
Lamehi-Rachti, M.; Mittig, W.
1976-01-01
The inequality of Bell has been tested by the measurement of the spin correlation in proton-proton scattering. Measurements were made at E/sub p/ = 13.2 and 13.7 MeV using carbon analyzers of 18.6 and 29 mg/cm 2 , respectively, accumulating a total of 10 4 coincidences. The experimental analyzing power, geometric correlation coefficients, and energy spectra are compared to the result of a Monte Carlo simulation of the apparatus. The results are in good agreement with quantum mechanics and in disagreement with the inequality of Bell if the same additional assumptions are made. The conditions for comparing the results of the experiments to the inequality of Bell are discussed
Drug-resistant molecular mechanism of CRF01_AE HIV-1 protease due to V82F mutation
Liu, Xiaoqing; Xiu, Zhilong; Hao, Ce
2009-05-01
Human immunodeficiency virus type 1 protease (HIV-1 PR) is one of the major targets of anti-AIDS drug discovery. The circulating recombinant form 01 A/E (CRF01_AE, abbreviated AE) subtype is one of the most common HIV-1 subtypes, which is infecting more humans and is expanding rapidly throughout the world. It is, therefore, necessary to develop inhibitors against subtype AE HIV-1 PR. In this work, we have performed computer simulation of subtype AE HIV-1 PR with the drugs lopinavir (LPV) and nelfinavir (NFV), and examined the mechanism of resistance of the V82F mutation of this protease against LPV both structurally and energetically. The V82F mutation at the active site results in a conformational change of 79's loop region and displacement of LPV from its proper binding site, and these changes lead to rotation of the side-chains of residues D25 and I50'. Consequently, the conformation of the binding cavity is deformed asymmetrically and some interactions between PR and LPV are destroyed. Additionally, by comparing the interactive mechanisms of LPV and NFV with HIV-1 PR we discovered that the presence of a dodecahydroisoquinoline ring at the P1' subsite, a [2-(2,6-dimethylphenoxy)acetyl]amino group at the P2' subsite, and an N2 atom at the P2 subsite could improve the binding affinity of the drug with AE HIV-1 PR. These findings are helpful for promising drug design.
Directory of Open Access Journals (Sweden)
Chunde Piao
2015-01-01
Full Text Available Based on FBG fiber Bragg grating technology and BOTDA distributed optical fiber sensing technology, this study uses fine sand to simulate overburden layer in vertical shaft model equipment. It studies the placing technique and test method for optical fiber sensors in the overburden layer, combined with MODFLOW software to simulate the change of the water head value when the overburden layer is losing water, and obtains the deformation features of overburden layer. The results show, at the beginning of water loss, the vertical deformation increases due to larger hydraulic pressure drop, while the deformation decreases gradually and tends to be stable with the hydraulic pressure drop reducing. The circumferential deformation is closely related to such factors as the distance between each drainage outlet, the variations of water head value, and the method of drainage. The monitoring result based on optical fiber sensing technology is consistent with the characteristics of water loss in overburden layer simulated by MODFLOW software, which shows that the optical fiber sensing technology applied to monitor shaft overburden layer is feasible.
Thermal-neutron multiple scattering: critical double scattering
International Nuclear Information System (INIS)
Holm, W.A.
1976-01-01
A quantum mechanical formulation for multiple scattering of thermal-neutrons from macroscopic targets is presented and applied to single and double scattering. Critical nuclear scattering from liquids and critical magnetic scattering from ferromagnets are treated in detail in the quasielastic approximation for target systems slightly above their critical points. Numerical estimates are made of the double scattering contribution to the critical magnetic cross section using relevant parameters from actual experiments performed on various ferromagnets. The effect is to alter the usual Lorentzian line shape dependence on neutron wave vector transfer. Comparison with corresponding deviations in line shape resulting from the use of Fisher's modified form of the Ornstein-Zernike spin correlations within the framework of single scattering theory leads to values for the critical exponent eta of the modified correlations which reproduce the effect of double scattering. In addition, it is shown that by restricting the range of applicability of the multiple scattering theory from the outset to critical scattering, Glauber's high energy approximation can be used to provide a much simpler and more powerful description of multiple scattering effects. When sufficiently close to the critical point, it provides a closed form expression for the differential cross section which includes all orders of scattering and has the same form as the single scattering cross section with a modified exponent for the wave vector transfer
Scattering Solar Thermal Concentrators
Energy Technology Data Exchange (ETDEWEB)
Giebink, Noel C. [Pennsylvania State Univ., State College, PA (United States)
2015-01-31
This program set out to explore a scattering-based approach to concentrate sunlight with the aim of improving collector field reliability and of eliminating wind loading and gross mechanical movement through the use of a stationary collection optic. The approach is based on scattering sunlight from the focal point of a fixed collection optic into the confined modes of a sliding planar waveguide, where it is transported to stationary tubular heat transfer elements located at the edges. Optical design for the first stage of solar concentration, which entails focusing sunlight within a plane over a wide range of incidence angles (>120 degree full field of view) at fixed tilt, led to the development of a new, folded-path collection optic that dramatically out-performs the current state-of-the-art in scattering concentration. Rigorous optical simulation and experimental testing of this collection optic have validated its performance. In the course of this work, we also identified an opportunity for concentrating photovoltaics involving the use of high efficiency microcells made in collaboration with partners at the University of Illinois. This opportunity exploited the same collection optic design as used for the scattering solar thermal concentrator and was therefore pursued in parallel. This system was experimentally demonstrated to achieve >200x optical concentration with >70% optical efficiency over a full day by tracking with <1 cm of lateral movement at fixed latitude tilt. The entire scattering concentrator waveguide optical system has been simulated, tested, and assembled at small scale to verify ray tracing models. These models were subsequently used to predict the full system optical performance at larger, deployment scale ranging up to >1 meter aperture width. Simulations at an aperture widths less than approximately 0.5 m with geometric gains ~100x predict an overall optical efficiency in the range 60-70% for angles up to 50 degrees from normal. However, the
Lin, Yung-Sheng; Tzeng, Yau-Ting; Chang, Chien-Cheng; Chu, Chin-Chou
2017-11-01
A numerical study is conducted to investigate the force mechanisms for a 3D heaving flexible plate from the perspective of a diagnostic force element analysis (Chang 1992). The problem is relevant to a simplified flapping fish-tail with the front edge held fixed in space. The flow is assumed to be laminar with the Reynolds numbers fixed at Re =200 or 500, and the Strouhal number St ranging from 0.1 to 0.6, and the flexure amplitude of the plate a0 for 0.1 to 0.25 (dimensionless). It is shown that heaving, whilst increasing thrust generation, also reduces the frictional drag, yet the flexibility promotes thrust generation at the expense of accruing more frictional drag. In the literature, the thrust exerted on the tail-mimicking plate is largely credited to the vortices in the wake. However, this study performs a regional force analysis to show that the vorticity in the wake region supplies approximately 20-30% of the total thrust, especially in the cases of strong thrust generation. Comparable contributions come also from the regions direct above and below the heaving plate (mainly including the attached vortices) as well as from the two side regions (mainly including the tip vortices) next to the flapping plate. In addition, the potential motion associated with the unsteady flapping and the contribution from the surface vorticity are non-negligible constituent force components. MOST, TAIWAN under Contacts NO. 105-2221-E-002-097-MY3 and NO. 105-2221-E-002 -105 -MY3.
Donne, A. J. H.
1994-01-01
Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is
Applied electromagnetic scattering theory
Osipov, Andrey A
2017-01-01
Besides classical applications (radar and stealth, antennas, microwave engineering), scattering and diffraction are enabling phenomena for some emerging research fields (artificial electromagnetic materials or metamaterials, terahertz technologies, electromagnetic aspects of nano-science). This book is a tutorial for advanced students who need to study diffraction theory. The textbook gives fundamental knowledge about scattering and diffraction of electromagnetic waves and provides some working examples of solutions for practical high-frequency scattering and diffraction problems. The book focuses on the most important diffraction effects and mechanisms influencing the scattering process and describes efficient and physically justified simulation methods - physical optics (PO) and the physical theory of diffraction (PTD) - applicable in typical remote sensing scenarios. The material is presented in a comprehensible and logical form, which relates the presented results to the basic principles of electromag...
International Nuclear Information System (INIS)
Sitenko, A.
1991-01-01
This book emerged out of graduate lectures given by the author at the University of Kiev and is intended as a graduate text. The fundamentals of non-relativistic quantum scattering theory are covered, including some topics, such as the phase-function formalism, separable potentials, and inverse scattering, which are not always coverded in textbooks on scattering theory. Criticisms of the text are minor, but the reviewer feels an inadequate index is provided and the citing of references in the Russian language is a hindrance in a graduate text
International Nuclear Information System (INIS)
Stirling, W.G.; Perry, S.C.
1996-01-01
We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO 3 is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs
Inversion assuming weak scattering
DEFF Research Database (Denmark)
Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus
2013-01-01
due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...
Light scattering by soap films
Vrij, A.
A theory is constructed describing the scattering from a liquid film (e.g., a soap film) of a light beam polarized normal to the plane of incidence. This scattering is due to the small irregular corrugations caused by thermal motion. The interference of the reflected incident beam with its multiple
International Nuclear Information System (INIS)
Firsova, N E; Firsov, Yu A
2012-01-01
For the first time the influence of out-of-plane deformations, which always exist in graphene, on the non-stationary processes is considered for the case of a monolayer graphene nanoresonator. A new loss mechanism for this device caused by dissipative intra-valley currents stipulated by synthetic electric fields is studied. These fields are generated by time-dependent gauge fields arising in a graphene membrane due to its intrinsic out-of-plane distortions and the influence of the external periodic electromotive force. The corresponding formula for the quality factor has a quantum mechanical origin and includes quantum mechanical parameters. This loss mechanism accounts for an essential part (about 40%) of losses in a graphene nanoresonator and it is specific just for graphene. The ways of minimization of this kind of dissipation (an increase in the quality factor of the electromechanical system) are discussed. It is explained why one can enhance the quality factor by correctly choosing a combination of strains (by strain engineering). In addition, it is shown that the quality factor can be increased by switching on a magnetic field perpendicular to the graphene membrane.
Protasiewicz, Marcin; Rojek, Aleksandra; Gajek, Jacek; Mysiak, Andrzej
2013-01-01
We report a case of a 65-year-old female patient after replacement of aortic and mitral valve with mechanical prostheses and implantation of a pacemaker hospitalized in our clinic due to acute coronary syndrome complicated with cardiac arrest due to ventricular fibrillation. The electrocardiogram performed on admission showed signs of myocardial infarction with concomitant ventricular pacing. After successful resuscitation the coronary angiography was performed, which showed occlusion of the left circumflex artery (LCx) by thrombus. On the basis of intravascular ultrasound imaging the presence of vulnerable plaque, parietal thrombus and dissection of LCx were excluded. It suggested that occlusion of the LCx resulted from its embolism by left-sided heart thrombus due to subtherapeutic oral anticoagulation. In this case suboptimal anticoagulation was partially iatrogenic. Two weeks before the patient had been given vitamin K intravenously due to indeterminable international normalized ratio (INR) level, which caused transient resistance to oral anticoagulants. This case report illustrates tragic difficulties in the treatment with vitamin K antagonists, which concern as many as 2/3 of anticoagulated patients. These troubles contributed to the search for new, more efficient and safer anticoagulants. There are two classes of new oral anticoagulant drugs, which do not require monitoring of coagulation: direct thrombin inhibitors (e.g. dabigatran) and factor Xa inhibitors (e.g. rivaroxaban). In spite of their proven efficacy in the prevention of ischaemic stroke related to atrial fibrillation and prevention or treatment of deep vein thrombosis and pulmonary embolism, the use of new oral anticoagulants for the treatment of patients with mechanical valve prostheses needs further research.
International Nuclear Information System (INIS)
Christillin, P.
1986-01-01
The theory of nuclear Compton scattering is reformulated with explicit consideration of both virtual and real pionic degrees of freedom. The effects due to low-lying nuclear states, to seagull terms, to pion condensation and to the Δ dynamics in the nucleus and their interplay in the different energy regions are examined. It is shown that all corrections to the one-body terms, of diffractive behaviour determined by the nuclear form factor, have an effective two-body character. The possibility of using Compton scattering as a complementary source of information about nuclear dynamics is restressed. (author)
International Nuclear Information System (INIS)
Botto, D.J.; Pratt, R.H.
1979-05-01
The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A -2 based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required
Energy Technology Data Exchange (ETDEWEB)
Botto, D.J.; Pratt, R.H.
1979-05-01
The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.
International Nuclear Information System (INIS)
Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Li, Yinsheng; Sugino, Hideharu
2011-01-01
The magnitude of Niigata-ken Chuetsu-Oki earthquake in 2007 was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the crack growth behaviors due to the cyclic overload like large earthquake. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor (ΔK). However, ΔK is inappropriate in a loading condition beyond small scale yielding. In this study, the crack growth behaviors for piping materials were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic overload beyond small scale yielding could be the sum of fatigue and ductile crack growth. The retardation effect of excessive loading on the crack growth was observed after the loading. The modified Wheeler model using J-integral has been proposed for the prediction of retardation effect. Finally, an evaluation method for crack growth behaviors due to the cyclic overload is suggested. (author)
Influence of interface scattering on shock waves in heterogeneous solids
International Nuclear Information System (INIS)
Zhuang Shiming; Ravichandran, Guruswami; Grady, Dennis E.
2002-01-01
In heterogeneous media, the scattering due to interfaces between dissimilar materials play an important role in shock wave dissipation and dispersion. In this work the influence of interface scattering effect on shock waves was studied by impacting flyer plates onto periodically layered polycarbonate/6061 aluminum, polycarbonate/304 stainless steel and polycarbonate/glass composites. The experimental results (using VISAR and stress gauges) indicate that the rise time of the shock front decreases with increasing shock strength, and increases with increasing mechanical impedance mismatch between layers; the strain rate at the shock front increases by about the square of the shock stress. Experimental and numerical results also show that due to interface scattering effect the shock wave velocity in periodically layered composites decreases. In some cases the shock velocity of a layered heterogeneous composite can be lower than that of either of its components
X-ray scattering of soft matter
International Nuclear Information System (INIS)
Stribeck, N.
2007-01-01
This coherently written volume summarizes the analytical power of modern X-ray scattering in the field of soft matter. Applications of X-ray scattering to soft matter have advanced considerably within recent years, both conceptually and technically. There are now mature high-power X-ray sources, synchrotrons and rotating anodes, as well as high-speed detectors, which have become readily available and which make the whole process more viable. High-quality time-resolved experiments on polymer structure can now be performed with ease, a major advancement due to the genuine power of the scattering method. This manual is a detailed description of simple tools that can elucidate the mechanisms of structure evolution in the studied materials. It is also a step-by-step guide to more advanced methods of the latest X-ray scattering techniques, and breaks down these methods. Data analysis based on clear, unequivocal results is rendered simple and straightforward - with a stress on the careful planning of experiments and adequate recording of all required data. This book, then, serves as a useful ready-reference guide. It has been written for the modern scientist who is a generalist and needs a concise reference, and demonstrates typical errors in data evaluation. (orig.)
Inelastic scattering of neutrons
International Nuclear Information System (INIS)
Sal'nikov, O.A.
1984-06-01
The paper reviews the main problems concerning the mechanism of the inelastic scatterings of neutrons by nuclei, concentrating on the different models which calculate the angular distributions. In the region of overlapping levels, both the compound nucleus mechanism and the preequilibrium Griffin (exciton) model are discussed, and their contribution relative to that of a direct mechanism is considered. The parametrization of the level density and of the nuclear moment of inertia are also discussed. The excitation functions of discrete levels are also presented, and the importance of elucidating their five structure (for practical calculations, such as for shielding) is pointed out
International Nuclear Information System (INIS)
Mermaz, M.C.
1984-01-01
Diffraction and refraction play an important role in particle elastic scattering. The optical model treats correctly and simultaneously both phenomena but without disentangling them. Semi-classical discussions in terms of trajectories emphasize the refractive aspect due to the real part of the optical potential. The separation due to to R.C. Fuller of the quantal cross section into two components coming from opposite side of the target nucleus allows to understand better the refractive phenomenon and the origin of the observed oscillations in the elastic scattering angular distributions. We shall see that the real part of the potential is responsible of a Coulomb and a nuclear rainbow which allows to determine better the nuclear potential in the interior region near the nuclear surface since the volume absorption eliminates any effect of the real part of the potential for the internal partial scattering waves. Resonance phenomena seen in heavy ion scattering will be discussed in terms of optical model potential and Regge pole analysis. Compound nucleus resonances or quasi-molecular states can be indeed the more correct and fundamental alternative
Correlation in atomic scattering
International Nuclear Information System (INIS)
McGuire, J.H.
1987-01-01
Correlation due to the Coulomb interactions between electrons in many-electron targets colliding with charged particles is formulated, and various approximate probability amplitudes are evaluated. In the limit that the electron-electron, 1/r/sub i//sub j/, correlation interactions are ignored or approximated by central potentials, the independent-electron approximation is obtained. Two types of correlations, or corrections to the independent-electron approximation due to 1/r/sub i//sub j/ terms, are identified: namely, static and scattering correlation. Static correlation is that contained in the asymptotic, e.g., bound-state, wave functions. Scattering correlation, arising from correlation in the scattering operator, is new and is considered in some detail. Expressions for a scattering correlation amplitude, static correlation or rearrangement amplitude, and independent-electron or direct amplitude are derived at high collision velocity and compared. At high velocities the direct and rearrangement amplitudes dominate. At very high velocities, ν, the rearrangement amplitude falls off less rapidly with ν than the direct amplitude which, however, is dominant as electron-electron correlation tends to zero. Comparisons with experimental observations are discussed
Squire, O. J.; Archibald, A. T.; Griffiths, P. T.; Jenkin, M. E.; Smith, D.; Pyle, J. A.
2015-05-01
Isoprene is a~precursor to tropospheric ozone, a key pollutant and greenhouse gas. Anthropogenic activity over the coming century is likely to cause large changes in atmospheric CO2 levels, climate and land use, all of which will alter the global vegetation distribution leading to changes in isoprene emissions. Previous studies have used global chemistry-climate models to assess how possible changes in climate and land use could affect isoprene emissions and hence tropospheric ozone. The chemistry of isoprene oxidation, which can alter the concentration of ozone, is highly complex, therefore it must be parameterised in these models. In this work, we compare the effect of four different reduced isoprene chemical mechanisms, all currently used in Earth system models, on tropospheric ozone. Using a box model we compare ozone in these reduced schemes to that in a more explicit scheme (the Master Chemical Mechanism) over a range of NOx and isoprene emissions, through the use of O3 isopleths. We find that there is some variability, especially at high isoprene emissions, caused by differences in isoprene-derived NOx reservoir species. A global model is then used to examine how the different reduced schemes respond to potential future changes in climate, isoprene emissions, anthropogenic emissions and land use change. We find that, particularly in isoprene-rich regions, the response of the schemes varies considerably. The wide-ranging response is due to differences in the model descriptions of the peroxy radical chemistry, particularly their relative rates of reaction towards NO, leading to ozone formation, or HO2, leading to termination. Also important is the yield of isoprene nitrates and peroxyacyl nitrate precursors from isoprene oxidation. Those schemes that produce less of these NOx reservoir species, tend to produce more ozone locally and less away from the source region. We also note changes in other key oxidants such as NO3 and OH (due to the inclusion of
International Nuclear Information System (INIS)
Leader, Elliot
1991-01-01
With very few unexplained results to challenge conventional ideas, physicists have to look hard to search for gaps in understanding. An area of physics which offers a lot more than meets the eye is elastic and diffractive scattering where particles either 'bounce' off each other, emerging unscathed, or just graze past, emerging relatively unscathed. The 'Blois' workshops provide a regular focus for this unspectacular, but compelling physics, attracting highly motivated devotees
International Nuclear Information System (INIS)
1991-02-01
The annual report on hand gives an overview of the research work carried out in the Laboratory for Neutron Scattering (LNS) of the ETH Zuerich in 1990. Using the method of neutron scattering, it is possible to examine in detail the static and dynamic properties of the condensed material. In accordance with the multidisciplined character of the method, the LNS has for years maintained a system of intensive co-operation with numerous institutes in the areas of biology, chemistry, solid-state physics, crystallography and materials research. In 1990 over 100 scientists from more than 40 research groups both at home and abroad took part in the experiments. It was again a pleasure to see the number of graduate students present, who were studying for a doctorate and who could be introduced into the neutron scattering during their stay at the LNS and thus were in the position to touch on central ways of looking at a problem in their dissertation using this modern experimental method of solid-state research. In addition to the numerous and interesting ways of formulating the questions to explain the structure, nowadays the scientific programme increasingly includes particularly topical studies in connection with high temperature-supraconductors and materials research
Friedrich, Harald
2016-01-01
This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...
Scattering Effect on Anomalous Hall Effect in Ferromagnetic Transition Metals
Zhang, Qiang
2017-11-30
The anomalous Hall effect (AHE) has been discovered for over a century, but its origin is still highly controversial theoretically and experimentally. In this study, we investigated the scattering effect on the AHE for both exploring the underlying physics and technical applications. We prepared Cox(MgO)100-x granular thin films with different Co volume fraction (34≤≤100) and studied the interfacial scattering effect on the AHE. The STEM HAADF images confirmed the inhomogeneous granular structure of the samples. As decreases from 100 to 34, the values of longitudinal resistivity () and anomalous Hall resistivity (AHE) respectively increase by about four and three orders in magnitude. The linear scaling relation between the anomalous Hall coefficient () and the measured at 5 K holds in both the as-prepared and annealed samples, which suggests a skew scattering dominated mechanism in Cox(MgO)100-x granular thin films. We prepared (Fe36//Au12/), (Ni36//Au12/) and (Ta12//Fe36/) multilayers to study the interfacial scattering effect on the AHE. The multilayer structures were characterized by the XRR spectra and TEM images of cross-sections. For the three serials of multilayers, both the and AHE increase with , which clearly shows interfacial scattering effect. The intrinsic contribution decreases with increases in the three serials of samples, which may be due to the crystallinity decaying or the finite size effect. In the (Fe36//Au12/) samples, the side-jump contribution increases with , which suggests an interfacial scattering-enhanced side jump. In the (Ni36//Au12/) samples, the side-jump contribution decreases with increases, which could be explained by the opposite sign of the interfacial scattering and grain boundary scattering contributed side jump. In the (Ta12//Fe36/) multilayers, the side-jump contribution changed from negative to positive, which is also because of the opposite sign of the interfacial scattering and grain boundary scattering
Use of implicit Monte Carlo radiation transport with hydrodynamics and compton scattering
International Nuclear Information System (INIS)
Fleck, J.A. Jr.
1971-03-01
It is shown that the combination of implicit radiation transport and hydrodynamics, Compton scattering, and any other energy transport can be simply carried out by a ''splitting'' procedure. Contributions to material energy exchange can be reckoned separately for hydrodynamics, radiation transport without scattering, Compton scattering, plus any other possible energy exchange mechanism. The radiation transport phase of the calculation would be implicit, but the hydrodynamics and Compton portions would not, leading to possible time step controls. The time step restrictions which occur on radiation transfer due to large Planck mean absorption cross-sections would not occur
Surface-enhanced Raman scattering from silver electrodes
International Nuclear Information System (INIS)
Trott, G.R.
1982-01-01
The chemical and physical origins of the anomalously large enhancement of the Raman scattering cross section for molecules adsorbed on silver electrodes in an electrochemical cell were investigated. The effect of the chemical reactions which occur during the anodization/activation procedure were studied using the Ag-CN system. It was shown that the function of the anodization process is to roughen the electrode surface and create an activated site for bonding to the cyanide. A new nonelectrochemical technique for activating the silver surface, along with a study of the enhanced cyanide Raman scattering in different background electrolytes, showed that the Raman active entity on the surface must be a silver-cyanide complex. In order to study the physical mechanism of the enhancement, the angular dependence of the scattered radiation was measured from pyridine adsorbed on an evaporated silver electrode. Both polycrystalline and single crystalline silver films were used. The angular dependence of the scattered radiation from these films showed that the metal surface was controlling the directional properties of the scattered radiation, and not the polarizability tensor of the adsorbate. Based on these experimental results, it was concluded that for weakly roughened silver electrodes the source of the anomalous enhancement is due to a resonant Raman scattering process
Laser-induced speckle scatter patterns in Bacillus colonies
Directory of Open Access Journals (Sweden)
Huisung eKim
2014-10-01
Full Text Available Label-free bacterial colony phenotyping technology called BARDOT (BActerial Rapid Detection using Optical scattering Technology provided successful classification of several different bacteria at the genus, species, and serovar level. Recent experiments with colonies of Bacillus species provided strikingly different characteristics of elastic light scatter (ELS patterns, which were comprised of random speckles compared to other bacteria, which are dominated by concentric rings and spokes. Since this laser-based optical sensor interrogates the whole volume of the colony, 3-D information of micro- and macro-structures are all encoded in the far-field scatter patterns. Here, we present a theoretical model explaining the underlying mechanism of the speckle formation by the colonies from Bacillus species. Except for Bacillus polymyxa, all Bacillus spp. produced random bright spots on the imaging plane, which presumably dependent on the cellular and molecular organization and content within the colony. Our scatter model-based analysis revealed that colony spread resulting in variable surface roughness can modify the wavefront of the scatter field. As the center diameter of the Bacillus spp. colony grew from 500 μm to 900 μm, average speckles area decreased 2-fold and the number of small speckles increased 7-fold. In conclusion, as Bacillus colony grows, the average speckle size in the scatter pattern decreases and the number of smaller speckle increases due to the swarming growth characteristics of bacteria within the colony.
Superradiative scattering magnons
International Nuclear Information System (INIS)
Shrivastava, K.N.
1980-01-01
A magnon-photon interaction for the magnetic vector of the electromagnetic wave perpendicular to the direction of magnetization in a ferromagnet is constructed. The magnon part of the interaction is reduced with the use of Bogoliubov transformation. The resulting magnon-photon interaction is found to contain several interesting new radiation effects. The self energy of the magnon is calculated and life times arising from the radiation scattering are predicted. The magnon frequency shift due to the radiation field is found. One of the terms arising from the one-magnon one-photon scattering gives a line width in reasonable agreement with the experimentally measured value of ferromagnetic resonance line width in yttrium iron garnet. Surface magnon scattering is indicated and the contribution of this type of scattering to the radiative line width is discussed. The problem of magnetic superradiance is indicated and it is shown that in anisotropic ferromagnets the emission is proportional to the sqare of the number of magnons and the divergence is considerably minimized. Accordingly the magnetic superradiance emerges as a hyperradiance with much more radiation intensity than in the case of disordered atomic superradiance. (author)
Energy Technology Data Exchange (ETDEWEB)
Friedrich, Harald [Technische Univ. Muenchen, Garching (Germany). Physik-Department
2016-07-01
This corrected and updated second edition of ''Scattering Theory'' presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is kept as low as at all possible and deeper questions related to the mathematical foundations of scattering theory are passed by. It should be understandable for anyone with a basic knowledge of nonrelativistic quantum mechanics. The book is intended for advanced students and researchers, and it is hoped that it will be useful for theorists and experimentalists alike.
De Wolf, E.A.
2002-01-01
We discuss basic concepts and properties of diffractive phenomena in soft hadron collisions and in deep-inelastic scattering at low Bjorken-x. The paper is not a review of the rapidly developing field but presents an attempt to show in simple terms the close inter-relationship between the dynamics of high-energy hadronic and deep-inelastic diffraction. Using the saturation model of Golec-Biernat and Wusthoff as an example, a simple explanation of geometrical scaling is presented. The relation between the QCD anomalous multiplicity dimension and the Pomeron intercept is discussed.
International Nuclear Information System (INIS)
Wolf, E.A. de
2002-01-01
We discuss basic concepts and properties of diffractive phenomena in soft hadron collisions and in deep-inelastic scattering at low Bjorken - x. The paper is not a review of the rapidly developing field but presents an attempt to show in simple terms the close inter-relationship between the dynamics of high-energy hadronic and deep-inelastic diffraction. Using the saturation model of Golec-Biernat and Wuesthoff as an example, a simple explanation of geometrical scaling is presented. The relation between the QCD anomalous multiplicity dimension and the Pomeron intercept is discussed. (author)
International Nuclear Information System (INIS)
Sanghera, G.S.
1999-01-01
The Occupational Health and Safety (OHS) Act requires that every employer shall ensure the health and safety of workers in the workplace. Issues regarding the practices at workplaces and how they should reflect the standards of due diligence were discussed. Due diligence was described as being the need for employers to identify hazards in the workplace and to take active steps to prevent workers from potentially dangerous incidents. The paper discussed various aspects of due diligence including policy, training, procedures, measurement and enforcement. The consequences of contravening the OHS Act were also described
Energy Technology Data Exchange (ETDEWEB)
Kato, T; Tachibana, S; Inden, T
1974-12-01
The mechanism of crop injury by nitrogen dioxide gas was investigated by exploring kidney bean, cucumber, tomato, egg plant, and spinach plants 6.0 to 17 ppM NO/sub 2/ under various conditions. The application of aqueous oxyethylene decasanol on crop leaves reduced the injury due to the gas, expecially on the lower leaf sides. Leaves exposed to NO/sub 2/ in the dark showed severer injury and contained more nitrite anion than those exposed to NO/sub 2/ in the light. Leaves smeared with an aqueous sodium nitrite solution showed the same type of injury as that induced by NO/sub 2/. After treatment with 3-(3,4-dichlorophenyl)-1,1- dimethylurea, the leaves became more susceptible to the gas even under light and formed more nitrite anion than controls. Plants grown in nitrate-nitrogen cultures were less susceptible to NO/sub 2/ damage than those grown in ammonia-nitrogen cultures or cultures without nitrogen and contained less nitrite anion than others. Plant injury by gaseous nitrogen dioxide appeared to be caused by nitrite anion. Susceptibility to NO/sub 2/ depended on the amount of the gas taken in by stomata and on the physiological activity of the plant which reduces the anion. The reduction is carried out by nitrite reductase. The photochemical reduction by reductase in chloroplasts appears to be related to the injury-reducing effect of light.
Phonon scattering by isotopic impurities
International Nuclear Information System (INIS)
Dacol, D.K.
1974-06-01
The effects upon vibrations of a perfect crystal lattice due to the replacement of some of its atoms by isotopes of these atoms are studied. The approach consists in considering the isotopic impurities as scattering centres for the quanta of the elastic waves the objective is to obtain the scattering amplitudes. These amplitudes are obtained through a canonical transformation method which was introduced by Chevalier and Rideau in the study of the Wentzel's model in quantum field theory
International Nuclear Information System (INIS)
Bagger, J.; Valencia, G.
1990-01-01
We use higher-order chiral Lagrangians to study W L W L scattering at the SSC. We analyze a model that is consistent with crossing, unitarity and chiral symmetry, with no resonant behavior at SSC energies. The only signal is a slightly enhanced rate for W L W L scattering. Our results indicate the level of sensitivity that must be reached before the SSC can be assured of discovering the mechanism for electroweak symmetry breaking. 19 refs., 4 figs., 2 tabs
International Nuclear Information System (INIS)
Wu Jiuhui; Zhang Siwen; Zhou Kejiang
2012-01-01
A physical mechanism of phononic band gap and resonant nanoacoustic scattering in an aggregate of two elastic nanospheres is presented in this paper. By considering the Van der Waals (VdW) force between two nanospheres illuminated by nanoacoustic wave, phononic band gap and frequency shift at the lower frequency side, and largely enhanced nanoacoustic scattering at the other frequency range have been found through calculating the form function of the acoustic scattering from the nanosystem. This VdW-force-induced band gap is different from the known mechanisms of Bragg scattering and local resonances for periodic media. It is shown that when the separation distance between two nanospheres is decreasing from 20 to 1 nm, due to the increasing VdW force, the nanoacoustic scattering is much heightened by two order of magnitude, and meanwhile the frequency shift and phononic band gap at the low frequencies are both widened. These results could provide potential applications of nanoacoustic devices.
International Nuclear Information System (INIS)
Lv, Yuanjie; Feng, Zhihong; Gu, Guodong; Han, Tingting; Yin, Jiayun; Liu, Bo; Cai, Shujun; Lin, Zhaojun; Ji, Ziwu; Zhao, Jingtao
2014-01-01
The electron mobility scattering mechanisms in AlN/GaN heterostuctures with 3 nm and 6 nm AlN barrier thicknesses were investigated by temperature-dependent Hall measurements. The effect of interface roughness (IFR) scattering on the electron mobility was found to be enhanced by increasing AlN barrier thickness. Moreover, using the measured capacitance-voltage and current-voltage characteristics of the fabricated heterostructure field-effect transistors (HFETs) with different Schottky areas on the two heterostuctures, the variations of electron mobility with different gate biases were investigated. Due to enhanced IFR scattering, the influence of polarization Coulomb field (PCF) scattering on electron mobility was found to decrease with increasing AlN barrier layer thickness. However, the PCF scattering remained an important scattering mechanism in the AlN/GaN HFETs.
Electron scattering by native defects in III-V nitrides and their alloys
International Nuclear Information System (INIS)
Hsu, L.; Walukiewicz, W.
1996-03-01
We have calculated the electron mobilities in GaN and InN taking into consideration scattering by short range potentials, in addition to all standard scattering mechanisms. These potentials are produced by the native defects which are responsible for the high electron concentrations in nominally undoped nitrides. Comparison of the calculated mobilities with experimental data shows that scattering by short range potentials is the dominant mechanism limiting the electron mobilities in unintentionally doped nitrides with large electron concentrations. In the case of Al x Ga 1-x N alloys, the reduction in the electron concentration due to the upward shift of the conduction band relative to the native defect level can account for the experimentally measured mobilities. Resonant scattering is shown to be important when the defect and Fermi levels are close in energy
Mechanisms for generating froissaron
International Nuclear Information System (INIS)
Glushko, N.I.; Kobylinski, N.A.; Martynov, E.S.; Shelest, V.P.
1982-01-01
From a common point of view, we consider the mechanisms for generating froissaron which arise due to the quasieikonal approximation, the U-matrix approach and the method of continued unitarity. A realistic model for the input pomeron is suggested and the data on high-energy pp-scattering are described. Likeness and difference of asymptotic and preasymptotic regimes for three variants of froissaron are discussed
Simulation of multiple scattering background in heavy ion backscattering spectrometry
International Nuclear Information System (INIS)
Li, M.M.; O'Connor, D.J.
1999-01-01
With the development of heavy ion backscattering spectrometry (HIBS) for the detection of trace quantities of heavy-atom impurities on Si surfaces, it is necessary to quantify the multiple scattering contribution to the spectral background. In the present work, the Monte Carlo computer simulation program TRIM has been used to study the backscattering spectrum and the multiple scattering background features for heavy ions C, Ne, Si, Ar and Kr impinging on four types of targets: (1) a single ultra-thin (free standing) Au film of 10 A thickness, (2) a 10 A Au film on a 50 A Si surface, (3) a 10 A Au film on an Si substrate (10 000 A), and (4) a thick target (10 000 A) of pure Si. The ratio of the signal from the Au thin layer to the background due to multiple scattering has been derived by fitting the simulation results. From the simulation results, it is found that the Au film contributes to the background which the Si plays a role in developing due to the ion's multiple scattering in the substrate. Such a background is generated neither by only the Au thin layer nor by the pure Si substrate independently. The corresponding mechanism of multiple scattering in the target can be explained as one large-angle scattering in the Au layer and subsequently several small angle scatterings in the substrate. This study allows an appropriate choice of incident beam species and energy range when the HIBS is utilized to analyse low level impurities in Si wafers
Directory of Open Access Journals (Sweden)
Rafael eTorres-Peralta
2016-01-01
Full Text Available To determine whether task failure during incremental exercise to exhaustion (IE is principally due to reduced neural drive and increased metaboreflex activation eleven men (22±2 years performed a 10s control isokinetic sprint (IS; 80 rpm after a short warm-up. This was immediately followed by an IE in normoxia (Nx, PIO2:143 mmHg and hypoxia (Hyp, PIO2:73 mmHg in random order, separated by a 120 min resting period. At exhaustion, the circulation of both legs was occluded instantaneously (300 mmHg during 10 or 60s to impede recovery and increase metaboreflex activation. This was immediately followed by an IS with open circulation. Electromyographic recordings were obtained from the vastus medialis and lateralis. Muscle biopsies and blood gases were obtained in separate experiments. During the last 10s of the IE, pulmonary ventilation, VO2, power output and muscle activation were lower in hypoxia than in normoxia, while pedaling rate was similar. Compared to the control sprint, performance (IS-Wpeak was reduced to a greater extent after the IE-Nx (11% lower P<0.05 than IE-Hyp. The root mean square (EMGRMS was reduced by 38 and 27% during IS performed after IE-Nx and IE-Hyp, respectively (Nx vs. Hyp: P<0.05. Post-ischemia IS-EMGRMS values were higher than during the last 10s of IE. Sprint exercise mean (IS-MPF and median (IS-MdPF power frequencies, and burst duration, were more reduced after IE-Nx than IE-Hyp (P<0.05. Despite increased muscle lactate accumulation, acidification, and metaboreflex activation from 10 to 60s of ischemia, IS-Wmean (+23% and burst duration (+10% increased, while IS-EMGRMS decreased (-24%, P<0.05, with IS-MPF and IS-MdPF remaining unchanged. In conclusion, close to task failure, muscle activation is lower in hypoxia than in normoxia. Task failure is predominantly caused by central mechanisms, which recover to great extent within one minute even when the legs remain ischemic. There is dissociation between the recovery of
Czech Academy of Sciences Publication Activity Database
Uhlířová, T.; Mojzeš, P.; Melníková Komínková, Zuzana; Kalbáč, Martin; Sutrová, Veronika; Šloufová, I.; Vlčková, B.
2017-01-01
Roč. 48, č. 10 (2017), s. 1270-1281 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:61388955 ; RVO:61389013 Keywords : graphene-enhanced Raman scattering * single-layer graphene * free base phthalocyanine * Raman excitation profiles * photoinduced charge transfer Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 2.969, year: 2016
Chaotic scattering and quantum dynamics
International Nuclear Information System (INIS)
Doron, Eyal.
1992-11-01
The main concern of this thesis is the application of the semiclassical approximation to quantum chaotic scattering systems. We deal with two separate, although interconnected, subjects. The first subject dealt with is the semiclassical characterization of the fluctuations of the S matrix. A particular important parameter is the magnetic field B, and we show how the correlation length and line shape of S matrix elements under a change of B may be derived. An effect which is present in many physical wave systems is absorption of energy flux. We show how absorption affects both the reflectivity and the scattering phase and time delay of a scattering system. In the second part of the thesis, we show how the formalism and results obtained from chaotic scattering can be applied to the investigation of closed chaotic systems, and in particular to chaotic billiards. The semiclassical expansion for billiards is presented. In the last part of the thesis we deal with the statistics of S matrices of chaotic scattering systems. The main message of this work is that scattering matrix, and its classical counterpart the Poincare Scattering Map can be used to yield a powerful formulation of the quantum mechanical dynamics of bounded systems. (author)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2012-01-01
The following topics are dealt with: Neutron scattering in contemporary research, neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)
Energy Technology Data Exchange (ETDEWEB)
Aprile, E; Cantale, G; Degli-Agosti, S; Hausammann, R; Heer, E; Hess, R; Lechanoine-LeLuc, C; Leo, W; Morenzoni, S; Onel, Y [Geneva Univ. (Switzerland). Dept. de Physique Nucleaire et Corpusculaire
1983-01-01
The aim of the elastic pp experimental program at SIN was to measure enough spin dependent parameters in order to do a direct experimental reconstruction of the elastic scattering amplitudes at a few energies between 400 and 600 MeV and at several angles between 38/sup 0/ cm and 90/sup 0/ cm. This reconstruction was not possible until recently due to lack of experimental data. Information instead has come mainly from phase shift analysis (PSA). The only way to extract the elastic scattering amplitudes without any hypotheses except those of basic symmetries, is to measure a sufficient set of spin dependent parameters at a given angle and energy. With this in view, the authors have measured at 448, 494, 515, 536 and 579 MeV, the polarization, the spin correlation parameters Asub(00nn), Asub(00ss), Asub(00kk), Asub(00ks), the 2-spin parameters Dsub(n0n0), Ksub(n00n), Dsub(s'0s0), Dsub(s'0k0) and the 3-spin parameters Msub(s'0sn), Msub(s'0kn) between 34/sup 0/ cm and 118/sup 0/ cm. A few of these parameters have also been measured at 560 and 470 MeV and at a few energies below 448 MeV. The indices refer to the polarization orientation of the scattered, recoil, beam and target particle respectively.
Bidirectional optical scattering facility
Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...
Multiple Scattering Model for Optical Coherence Tomography with Rytov Approximation
Li, Muxingzi
2017-01-01
of speckles due to multiple scatterers within the coherence length, and other random noise. Motivated by the above two challenges, a multiple scattering model based on Rytov approximation and Gaussian beam optics is proposed for the OCT setup. Some previous
National Research Council Canada - National Science Library
Bhat, K. Ramachandra; Benton, Betty J; Ray, Radharaman
2004-01-01
Poly (ADP-ribose) polymerase (PARP) modulates several cellular functional proteins by a mechanism in which the proteins are poly-ADP-ribosylated by transferring the ADP-ribose moieties from the enzyme substrate NAD+ to the proteins...
Casser, E; Israel, S; Schlatt, S; Nordhoff, V; Boiani, M
2018-05-09
What is the prevalence, reproducibility and biological significance of transcriptomic differences between sister blastomeres of the mouse 2-cell embryo? Sister 2-cell stage blastomeres are distinguishable from each other by mRNA analysis, attesting to the fact that differentiation starts mostly early in the mouse embryo; however, the interblastomere differences are poorly reproducible and invoke the combinatorial effects of known and new mechanisms of blastomere diversification. Transcriptomic datasets for single blastomeres in mice have been available for years but have never been systematically analysed together, although such an analysis may shed light onto some unclarified topics of early mammalian development. Two unknowns that remain are at which stage embryonic blastomeres start to diversify from each other and what is the molecular origin of that difference. At the earliest postzygotic stage, the 2-cell stage, opinions differ regarding the answer to these questions; one group claims that the first zygotic division yields two equal blastomeres capable of forming a full organism (totipotency) and another group claims evidence for interblastomere differences reminiscent of the prepatterning found in embryos of lower taxa. Regarding the molecular origin of interblastomere differences, there are four prevalent models which invoke 1) oocyte anisotropy, 2) sperm entry point, 3) partition errors of the transcript pool, and 4) asynchronous embryonic genome activation in the two blastomeres. Seven transcriptomic studies published between 2011 and 2017 were eligible for retrospective analysis, since both blastomeres of the mouse 2-cell embryo had been analysed individually regarding the original pair associations and since the datasets were made available in public repositories. Five of these studies, encompassing a total of 43 pairs of sister blastomeres, were selected for further analyses based on high interblastomere correlations of mRNA levels. A double cut
International Nuclear Information System (INIS)
Levin, F.S.; Krueger, H.
1977-01-01
We propose in this article that the non-Hermitian equations typical of some many-body scattering theories be used to help solve many-body bound-state problems. The basic idea is to exploit the channel nature of many-body bound states that must exist because bound states are obvious negative-energy extensions of scattering states. Since atomic, molecular, and nuclear systems all display multichannel effects for E > 0, at least through Pauli-principle effects if not through mass-transfer reactions, this use of positive-energy methods for solving bound-state problems could have wide applicability. The development used here is based on the channel-component-state method of the channel-coupling-array theory, recently described in detail for the E > 0 case, and various aspects of the formalism are discussed. Detailed calculations using simple approximations are discussed for H 2 + , one of the simplest systems displaying channel structure. Comparison with the exact, Born-Oppenheimer results of Wind show that the non-Hermitian-equation, channel-component values of the equilibrium separation and total binding energy are accurate to within 2%, while the dissociation energy is accurate to 10%. The resulting wave function is identical to that arising from the simplest MO calculation, for which these numbers are less accurate than the preceding by at least a factor of 3. We also show that identical particle symmetry for the H 2 + case reduces the pair of coupled (two-channel) equations to a single equation with an exchange term. Similar reductions will occur for larger numbers of identical particles, thus suggesting application of the formalism to atomic structure problems. A detailed analysis of the present numerical results, their general implications, and possible applications is also given
Hartog, J P Den
1961-01-01
First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e
Scattering theory and automorphic functions
International Nuclear Information System (INIS)
Lachaud, G.
1982-01-01
After a consideration of the Fourier expansion of an automorphic function corresponding to the group SL(2,R) and a description of the Eisenstein series the author describes the application of these results to the quantum mechanical scattering theory using the group SO(2,R). (HSI)
Energy Transfer in Scattering by Rotating Potentials
Indian Academy of Sciences (India)
Quantum mechanical scattering theory is studied for time-dependent Schrödinger operators, in particular for particles in a rotating potential. Under various assumptions about the decay rate at infinity we show uniform boundedness in time for the kinetic energy of scattering states, existence and completeness of wave ...
International Nuclear Information System (INIS)
Spencer, R.L.
1979-03-01
The theory of stimulated Thomson scattering is investigated both quantum mechanically and classically. Two monochromatic electromagnetic waves of like polarization travelling in opposite directions are allowed to interact for a time tau with the electrons in a collisionless plasma. The electromagnetic waves have frequencies well above the plasma frequency, and their difference frequency is allowed to range upward from the plasma frequency. With the difference frequency well above the plasma frequency, the rate at which energy is transferred from one wave to the other is calculated quantum mechanically, classically from a fluid theory, and classically from an independent electron theory. The rate is calculated in both the homogeneously broadened limit, and in the inhomogeneously broadened limit
Energy Technology Data Exchange (ETDEWEB)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner [eds.
2010-07-01
The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2013-01-01
The following topics are dealt with: Neutron sources, symmetry of crystals, nanostructures investigated by small-angle neutron scattering, structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic neutron scattering, strongly correlated electrons, polymer dynamics, applications of neutron scattering. (HSI)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2010-01-01
The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)
Potential scattering of Dirac particles
International Nuclear Information System (INIS)
Thaller, B.
1981-01-01
A quantum mechanical interpretation of the Dirac equation for particles in external electromagnetic potentials is discussed. It is shown that a consequent development of the Stueckelberg-Feynman theory into a probabilistic interpretation of the Dirac equation corrects some prejudices concerning negative energy states, Zitterbewegung and bound states in repulsive potentials and yields the connection between propagator theory and scattering theory. Limits of the Dirac equation, considered as a wave mechanical equation, are considered. (U.K.)
New method for solving multidimensional scattering problem
International Nuclear Information System (INIS)
Melezhik, V.S.
1991-01-01
A new method is developed for solving the quantum mechanical problem of scattering of a particle with internal structure. The multichannel scattering problem is formulated as a system of nonlinear functional equations for the wave function and reaction matrix. The method is successfully tested for the scattering from a nonspherical potential well and a long-range nonspherical scatterer. The method is also applicable to solving the multidimensional Schroedinger equation with a discrete spectrum. As an example the known problem of a hydrogen atom in a homogeneous magnetic field is analyzed
Fatigue and damage tolerance scatter models
Raikher, Veniamin L.
1994-09-01
Effective Total Fatigue Life and Crack Growth Scatter Models are proposed. The first of them is based on the power form of the Wohler curve, fatigue scatter dependence on mean life value, cycle stress ratio influence on fatigue scatter, and validated description of the mean stress influence on the mean fatigue life. The second uses in addition are fracture mechanics approach, assumption of initial damage existence, and Paris equation. Simple formulas are derived for configurations of models. A preliminary identification of the parameters of the models is fulfilled on the basis of experimental data. Some new and important results for fatigue and crack growth scatter characteristics are obtained.
Pakarinen, Harri
2012-12-01
sensitivity and specificity of both clinical tests were calculated using the standard 7.5-Nm external rotation stress test as reference. Outcome was assessed after a minimum of one year of follow-up. Olerud-Molander (OM) scoring system, RAND 36-Item Health Survey, and VAS to measure pain and function were used as outcome measures in all studies. In study 1, 85 (53%) fractures were treated operatively using the stability based fracture classification. Non-operatively treated patients reported less pain and better OM (good or excellent 89% vs. 71%) and VAS functional scores compared to operatively treated patients although they experienced more displacement of the distal fibula (0 mm 30% vs. 69%; 0-2 mm 65% vs. 25%) after treatment. No non-operatively treated patients required operative fracture fixation during follow-up. In study 2, AITFL exploration and suture lead to equal functional outcome (OM mean, 77 vs. 73) to no exploration or fixation. In study 3, the hook test had a sensitivity of 0.25 and a specificity of 0.98. The external rotation stress test had a sensitivity of 0.58 and a specificity of 0.9. Both tests had excellent interobserver reliability; the agreement was 99% for the hook test and 98% for the stress test. There was no statistically significant difference in functional scores (OM mean, 79.6 vs. 83.6) or pain between syndesmosis transfixation and no fixation groups (Study 4). Our results suggest that a simple stability-based fracture classification is useful in choosing between non-operative and operative treatment of ankle fractures; approximately half of the ankle fractures can be treated non-operatively with success. Our observations also suggest that relevant syndesmosis injuries are rare in ankle fractures due to an SER mechanism of injury. According to our research, syndesmotic repair or fixation in SER ankle fracture has no influence on functional outcome or pain after minimum one year compared with no fixation.
Energy Technology Data Exchange (ETDEWEB)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)
2010-07-01
The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2010-01-01
The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)
Nonlinear light scattering in a two component medium: optical limiting application
International Nuclear Information System (INIS)
Joudrier, Valerie
1998-01-01
Scattering is a fundamental manifestation of the interaction between matter and radiation, resulting from inhomogeneities in the refractive index, which decrease transmission. This phenomenon is then especially attractive for sensor protection from laser light by optical limiting. One of the methods to induce scattering at high incident energy is to make use of the Kerr effect where the index of refraction is intensity dependent. Thus, the idea is to use a two component medium with a good index matching between the two components at low intensity, resulting in the medium transparency, and to modify it, at high intensity, due to the non linearity of one component making the medium highly scattering. Some of the experimental and theoretical investigations concerning a new material (here, a cell containing some liquid with small silica particles as inclusion in it) are presented in the visible domain (I=532 nm), for the nanosecond protection regime, beginning, with the chemical synthesis of the sample. The experimental results concerning the optical limiting process are presented, showing that nonlinear scattering is clearly the dominant mechanism in confrontation with other potential nonlinear effects. Several complementary experiments are then performed to complete the nonlinear scattering characterization, involving the measurement of the angular distribution of scattered energy and the integrating sphere measurement. Further information are also gained by studying the time response of the nonlinearities with a dual-beam (pulsed-pump, cw probe) technique. The previous experimental data is also analyzed with some simple theoretical models to evaluate the nonlinearity of the material from optical limiting, the angular scattering and the total scattering energy measurements. The good match between all the analytical results permits to delineate the physical mechanisms responsible for the nonlinear scattering effect and to direct the final conclusion. (author) [fr
Optical modeling of plasma-deposited ZnO films: Electron scattering at different length scales
International Nuclear Information System (INIS)
Knoops, Harm C. M.; Loo, Bas W. H. van de; Smit, Sjoerd; Ponomarev, Mikhail V.; Weber, Jan-Willem; Sharma, Kashish; Kessels, Wilhelmus M. M.; Creatore, Mariadriana
2015-01-01
In this work, an optical modeling study on electron scattering mechanisms in plasma-deposited ZnO layers is presented. Because various applications of ZnO films pose a limit on the electron carrier density due to its effect on the film transmittance, higher electron mobility values are generally preferred instead. Hence, insights into the electron scattering contributions affecting the carrier mobility are required. In optical models, the Drude oscillator is adopted to represent the free-electron contribution and the obtained optical mobility can be then correlated with the macroscopic material properties. However, the influence of scattering phenomena on the optical mobility depends on the considered range of photon energy. For example, the grain-boundary scattering is generally not probed by means of optical measurements and the ionized-impurity scattering contribution decreases toward higher photon energies. To understand this frequency dependence and quantify contributions from different scattering phenomena to the mobility, several case studies were analyzed in this work by means of spectroscopic ellipsometry and Fourier transform infrared (IR) spectroscopy. The obtained electrical parameters were compared to the results inferred by Hall measurements. For intrinsic ZnO (i-ZnO), the in-grain mobility was obtained by fitting reflection data with a normal Drude model in the IR range. For Al-doped ZnO (Al:ZnO), besides a normal Drude fit in the IR range, an Extended Drude fit in the UV-vis range could be used to obtain the in-grain mobility. Scattering mechanisms for a thickness series of Al:ZnO films were discerned using the more intuitive parameter “scattering frequency” instead of the parameter “mobility”. The interaction distance concept was introduced to give a physical interpretation to the frequency dependence of the scattering frequency. This physical interpretation furthermore allows the prediction of which Drude models can be used in a specific
Lv, Y J; Song, X B; Wang, Y G; Fang, Y L; Feng, Z H
2016-12-01
Ultra-thin AlN/GaN heterostructure field-effect transistors (HFETs) with, and without, SiN passivation were fabricated by the same growth and device processes. Based on the measured DC characteristics, including the capacitance-voltage (C-V) and output current-voltage (I-V) curves, the variation of electron mobility with gate bias was found to be quite different for devices with, and without, SiN passivation. Although the AlN barrier layer is ultra thin (c. 3 nm), it was proved that SiN passivation induces no additional tensile stress and has no significant influence on the piezoelectric polarization of the AlN layer using Hall and Raman measurements. The SiN passivation was found to affect the surface properties, thereby increasing the electron density of the two-dimensional electron gas (2DEG) under the access region. The higher electron density in the access region after SiN passivation enhanced the electrostatic screening for the non-uniform distributed polarization charges, meaning that the polarization Coulomb field scattering has a weaker effect on the electron drift mobility in AlN/GaN-based devices.
Scattered radiation in fan beam imaging systems
International Nuclear Information System (INIS)
Johns, P.C.; Yaffe, M.
1982-01-01
Scatter-to-primary energy fluence ratios (S/P) have been studied for fan x-ray beams as used in CT scanners and slit projection radiography systems. The dependence of S/P on phantom diameter, distance from phantom to image receptor, and kilovoltage is presented. An empirical equation is given that predicts S/P over a wide range of fan beam imaging configurations. For CT body scans on a 4th-generation machine, S/P is approximately 5%. Scattered radiation can produce a significant cupping artefact in CT images which is similar to that due to beam hardening. When multiple slices are used in scanned slit radiography, they can be arranged such that the increase in S/P is negligible. Calculations of scatter-to-primary ratios for first order scattering showed that for fan beams the contribution of coherent scatter is comparable to or greater than that of incoherent first scatter
Classical trajectory in non-relativistic scattering
International Nuclear Information System (INIS)
Williams, A.C.
1978-01-01
With the statistical interpretation of quantum mechanics as a guide, the classical trajectory is incorporated into quantum scattering theory. The Feynman path integral formalism is used as a starting point, and classical transformation theory is applied to the phase of the wave function so derived. This approach is then used to derive an expression for the scattering amplitude for potential scattering. It is found that the amplitude can be expressed in an impact parameter representation similar to the Glauber formalism. Connections are then made to the Glauber approximation and to semiclassical approximations derived from the Feynman path integral formalism. In extending this analysis to projectile-nucleus scattering, an approximation scheme is given with the first term being the same as in Glauber's multiple scattering theory. Higher-order approximations, thus, are found to give corrections to the fixed scatterer form of the impulse approximation inherent in the Glauber theory
Energy Technology Data Exchange (ETDEWEB)
Borelli, L.; Tagliaferro, B. (R.B.L. Riello Bruciatori, Legnago Spa, Legnago (Italy)); Cossalter, V.; Da Lio, M. (Padua Univ. (Italy). Dip. di Ingegneria Meccanica)
1993-08-01
A new class of fuel oil burners has recently been developed by an Italian firm with the aim of obtaining high performances in terms of both energy efficiency and air pollution abatement. The innovative feature of these burners is that they are equipped with a device which permits the automatic and optimum regulation of the air fuel mixture independent of ambient and operating conditions. To reduce costs, the regulation system is a mechanical one instead of electronic which would require an expensive lambda probe. The mechanical regulating system controls air intake by simply taking into account two main combustion factors - ambient temperature and the nominal fuel flow rate. The special cam mechanism is thus classified as one which performs a single function with two degrees of freedom, i.e., the independent variables of ambient temperature and nominal fuel flow. One of the air intake valve's movements is governed by a temperature transducer, the other (primary), by a screw which allows the registering of the air flow during burner installation or upon completion of periodic maintenance checks. In addition to optimizing combustion control, this control technique affords the possibility to adapt the air flow to the different fuel flows obtained by changing the type of nozzle or supply pressure.
Neutron scattering studies of biological molecules suggest
Indian Academy of Sciences (India)
tions of temperature, pressure or solvent environment for survival. ... scale that depends on the scattering vector range and energy resolution of the in- .... the structures) are good indicators of global evolutionary adaptation mechanisms.
Introducing Scattering Theory with a Computer
Merrill, John R.
1973-01-01
Discusses a new method of presenting the scattering theory, including classical explanation of cross sections, quantum mechanical expressions for phase shifts, and use of a computer to solve problems. (CC)
On the microscopic foundation of scattering theory
International Nuclear Information System (INIS)
Moser, T.
2007-01-01
The aim of the thesis is to give a contribution to the microscopic foundation of scattering theory, i. e. to show, how the asymptotic formalism of scattering theory with objects like the S-matrix as well the initial and final asymptotics ψ in and ψ out can be derived from a microscopic description of the basic system. First the final statistics from a N-particle system through farly distant surfaces is derived. Thereafter we confine us to the 1-particle scattering and apply the final statistics in order to derive the scattering cross section from a microscopical description of the scattering situation. The basing dynamics are Bohm's mechanics, a theory on the motion of point particles, which reproduces all results of nonrelativistic quantum mechanics
Quantum scattering at low energies
DEFF Research Database (Denmark)
Derezinski, Jan; Skibsted, Erik
2009-01-01
For a class of negative slowly decaying potentials, including V(x):=−γ|x|−μ with 0quantum mechanical scattering theory in the low-energy regime. Using appropriate modifiers of the Isozaki–Kitada type we show that scattering theory is well behaved on the whole continuous spectrum...... of the Hamiltonian, including the energy 0. We show that the modified scattering matrices S(λ) are well-defined and strongly continuous down to the zero energy threshold. Similarly, we prove that the modified wave matrices and generalized eigenfunctions are norm continuous down to the zero energy if we use...... of the kernel of S(λ) experiences an abrupt change from passing from positive energies λ to the limiting energy λ=0 . This change corresponds to the behaviour of the classical orbits. Under stronger conditions one can extract the leading term of the asymptotics of the kernel of S(λ) at its singularities....
DEFF Research Database (Denmark)
Jensen, Malene Hillerup; Wahlund, Per-Olof; Toft, Katrine Nørgaard
2013-01-01
of biophysical and structural methods (field flow fractionation, dynamic and multiangle light scattering, circular dichroism, size exclusion chromatography, and crystallography), we propose a mechanism for the self-association expected to occur upon subcutaneous injection of this insulin analogue. SAXS data...... provide evidence of the in solution structure of the self-associated oligomer, which is a long straight rod composed of "tense" state insulin hexamers (T(6)-hexamers) as the smallest repeating unit. The smallest oligomer building block in the process is a T(6)T(6)-dihexamer. This tense dihexamer is formed...... by the allosteric change of the initial equilibrium between a proposed "relaxed" state R(6)-hexamer and an R(3)T(3)T(3)R(3)-dihexamer. The allosteric change from relaxed to tense is triggered by removal of phenol, mimicking subcutaneous injection. The data hence provide the first unequivocal evidence...
María Gómez Castro, Berta; De Simone, Silvia; Carrera, Jesús
2016-04-01
Nowadays, there are still some unsolved relevant questions which must be faced if we want to proceed to the hydraulic fracturing in a safe way. How much will the fracture propagate? This is one of the most important questions that have to be solved in order to avoid the formation of pathways leading to aquifer targets and atmospheric release. Will the fracture failure provoke a microseismic event? Probably this is the biggest fear that people have in fracking. The aim of this work (developed as a part of the EU - FracRisk project) is to understand the hydro-mechanical coupling that controls the shear of existing fractures and their propagation during a hydraulic fracturing operation, in order to identify the key parameters that dominate these processes and answer the mentioned questions. This investigation focuses on the development of a new C++ code which simulates hydro-mechanical coupling, shear movement and propagation of a fracture. The framework employed, called Kratos, uses the Finite Element Method and the fractures are represented with an interface element which is zero thickness. This means that both sides of the element lie together in the initial configuration (it seems a 1D element in a 2D domain, and a 2D element in a 3D domain) and separate as the adjacent matrix elements deform. Since we are working in hard, fragile rocks, we can assume an elastic matrix and impose irreversible displacements in fractures when rock failure occurs. The formulation used to simulate shear and tensile failures is based on the analytical solution proposed by Okada, 1992 and it is part of an iterative process. In conclusion, the objective of this work is to employ the new code developed to analyze the main uncertainties related with the hydro-mechanical behavior of fractures derived from the hydraulic fracturing operations.
Directory of Open Access Journals (Sweden)
Baridula Ravinder Reddy
2017-01-01
Full Text Available The strength of the welded joint obtained by solid state stir welding process was found to be improved as compared to fusion welding process. The deposition of reinforcements during friction stir welding process can further enhance the strength of the welded joint by locking the movement of grain boundaries. In the present study, the aluminium alloys AA2024 and AA7075 were welded effectively by depositing the multi-walled carbon nanotubes in to the stir zone. The mechanical properties and microstructures were studied by varying the traverse speed at constant rotational speed. The results show that rotating tool pin stirring action and heat input play an important role in controlling the grain size. The carbon nanotubes were found to be distributed uniformly at a welding speed (traverse speed of 80mm/min. This enhanced the mechanical properties of the welded joint. The microstructure and Electron dispersive X-ray analysis (EDX studies indicate that the deposition of carbon nanotubes in the stir zone was influenced by the traverse speed.
Wigner representation in scattering problems
International Nuclear Information System (INIS)
Remler, E.A.
1975-01-01
The basic equations of quantum scattering are translated into the Wigner representation. This puts quantum mechanics in the form of a stochastic process in phase space. Instead of complex valued wavefunctions and transition matrices, one now works with real-valued probability distributions and source functions, objects more responsive to physical intuition. Aside from writing out certain necessary basic expressions, the main purpose is to develop and stress the interpretive picture associated with this representation and to derive results used in applications published elsewhere. The quasiclassical guise assumed by the formalism lends itself particularly to approximations of complex multiparticle scattering problems is laid. The foundation for a systematic application of statistical approximations to such problems. The form of the integral equation for scattering as well as its mulitple scattering expansion in this representation are derived. Since this formalism remains unchanged upon taking the classical limit, these results also constitute a general treatment of classical multiparticle collision theory. Quantum corrections to classical propogators are discussed briefly. The basic approximation used in the Monte Carlo method is derived in a fashion that allows for future refinement and includes bound state production. The close connection that must exist between inclusive production of a bound state and of its constituents is brought out in an especially graphic way by this formalism. In particular one can see how comparisons between such cross sections yield direct physical insight into relevant production mechanisms. A simple illustration of scattering by a bound two-body system is treated. Simple expressions for single- and double-scattering contributions to total and differential cross sections, as well as for all necessary shadow corrections thereto, are obtained and compared to previous results of Glauber and Goldberger
Effects on the spectrum of the cosmic microwave background due to intergalactic dust
International Nuclear Information System (INIS)
Kurtz, R.C.
1981-01-01
A model for intergalactic dust composed of graphite grains is presented. The model is examined in the context of the Rayleigh approximation for results due to long-wavelength scattering and absorption by the grains. The temperature of the scattering grains as a function of redshift is found, based on reasonable assumptions of the density of optical wavelength radiation in the universe. Mechanisms for aligning the grains on a scale large enough to produce polarization in the microwave region are discussed. The results are used to predict features that may be present in the observed cosmic microwave background radiation spectrum
Carrier scattering in metals and semiconductors
Gantmakher, VF
1987-01-01
The transport properties of solids, as well as the many optical phenomena in them are determined by the scattering of current carriers. ``Carrier Scattering in Metals and Semiconductors'' elucidates the state of the art in the research on the scattering mechanisms for current carriers in metals and semiconductors and describes experiments in which these mechanisms are most dramatically manifested.The selection and organization of the material is in a form to prepare the reader to reason independently and to deal just as independently with available theoretical results and experimental
Scattering and multiple scattering in disordered materials
International Nuclear Information System (INIS)
Weaver, R.L.; Butler, W.H.
1992-01-01
The papers in this section were presented at a joint session of symposium V on Applications of Multiple Scattering Theory and of Symposium P on Disordered Systems. They show that the ideas of scattering theory can help us to understand a very broad class of phenomena
Multiple exchange and high-energy fixed-angle scattering
Halliday, I G; Orzalesi, C A; Tau, M
1975-01-01
The application of the eikonal ansatz to fermion fermion elastic scattering with Abelian vector gluon exchanges is discussed. The behaviours of the elastic scattering amplitude and the elastic form factor are considered and an important mechanism for fixed angle high energy elastic scattering is identified. (6 refs).
Chester, W
1979-01-01
When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How ever, the presentation is more sophisticated than might be considered appropri ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...
Inelastic scattering with Chebyshev polynomials and preconditioned conjugate gradient minimization.
Temel, Burcin; Mills, Greg; Metiu, Horia
2008-03-27
We describe and test an implementation, using a basis set of Chebyshev polynomials, of a variational method for solving scattering problems in quantum mechanics. This minimum error method (MEM) determines the wave function Psi by minimizing the least-squares error in the function (H Psi - E Psi), where E is the desired scattering energy. We compare the MEM to an alternative, the Kohn variational principle (KVP), by solving the Secrest-Johnson model of two-dimensional inelastic scattering, which has been studied previously using the KVP and for which other numerical solutions are available. We use a conjugate gradient (CG) method to minimize the error, and by preconditioning the CG search, we are able to greatly reduce the number of iterations necessary; the method is thus faster and more stable than a matrix inversion, as is required in the KVP. Also, we avoid errors due to scattering off of the boundaries, which presents substantial problems for other methods, by matching the wave function in the interaction region to the correct asymptotic states at the specified energy; the use of Chebyshev polynomials allows this boundary condition to be implemented accurately. The use of Chebyshev polynomials allows for a rapid and accurate evaluation of the kinetic energy. This basis set is as efficient as plane waves but does not impose an artificial periodicity on the system. There are problems in surface science and molecular electronics which cannot be solved if periodicity is imposed, and the Chebyshev basis set is a good alternative in such situations.
Neutron scattering from fractals
DEFF Research Database (Denmark)
Kjems, Jørgen; Freltoft, T.; Richter, D.
1986-01-01
The scattering formalism for fractal structures is presented. Volume fractals are exemplified by silica particle clusters formed either from colloidal suspensions or by flame hydrolysis. The determination of the fractional dimensionality through scattering experiments is reviewed, and recent small...
Scatter from optical components
International Nuclear Information System (INIS)
Stover, J.C.
1989-01-01
This book is covered under the following topics: measurement and analysis techniques; BRDF standards, comparisons, and anomalies; scatter measurement of several materials; scatter from contaminations; and optical system contamination: effects, measurement, and control
Geometrical effects in X-mode scattering
International Nuclear Information System (INIS)
Bretz, N.
1986-10-01
One technique to extend microwave scattering as a probe of long wavelength density fluctuations in magnetically confined plasmas is to consider the launching and scattering of extraordinary (X-mode) waves nearly perpendicular to the field. When the incident frequency is less than the electron cyclotron frequency, this mode can penetrate beyond the ordinary mode cutoff at the plasma frequency and avoid significant distortions from density gradients typical of tokamak plasmas. In the more familiar case, where the incident and scattered waves are ordinary, the scattering is isotropic perpendicular to the field. However, because the X-mode polarization depends on the frequency ratios and the ray angle to the magnetic field, the coupling between the incident and scattered waves is complicated. This geometrical form factor must be unfolded from the observed scattering in order to interpret the scattering due to density fluctuations alone. The geometrical factor is calculated here for the special case of scattering perpendicular to the magnetic field. For frequencies above the ordinary mode cutoff the scattering is relatively isotropic, while below cutoff there are minima in the forward and backward directions which go to zero at approximately half the ordinary mode cutoff density
International Nuclear Information System (INIS)
Szczesny, R.; Baranowski, A.; Beliczynski, J.
1982-01-01
Measurements by the reflection technique of characteristic electron energy losses (CEEL) with a primary electron beam of energy E 0 =1 keV have been carried out on polycrystal samples of Al. The sample surfaces have been mechanically cleaned in a dinamical vacuum of the order 10 -6 Tr before each measurement. The CEEL spectra have been corrected for the resolving power of the apparatus by the deconvolution method. We have ascertained that the measuring technique and elaboration data method are useful for quickly obtaining the plasmon energy loss spectrum for an investigated material. (author)
Uchida, Satoshi; Yoshida, Taketo; Tochikubo, Fumiyoshi
2017-10-01
Plasma medicine is one of the most attractive applications using atmospheric pressure nonequilibrium plasma. With respect to direct contact of the discharge plasma with a biological membrane, reactive oxygen species play an important role in induction of medical effects. However, complicated interactions between the plasma radicals and membrane have not been understood well. In the present work, we simulated elemental processes at the first stage of physicochemical interactions between oxygen atom and phosphatidylcholine using the quantum mechanical molecular dynamics code in a general software AMBER. The change in the above processes was classified according to the incident energy of oxygen atom. At an energy of 1 eV, the abstraction of a hydrogen atom and recombination to phosphatidylcholine were simultaneously occurred in chemical attachment of incident oxygen atom. The exothermal energy of the reaction was about 80% of estimated one based on the bond energies of ethane. An oxygen atom over 10 eV separated phosphatidylcholine partially. The behaviour became increasingly similar to physical sputtering. The reaction probability of oxygen atom was remarkably high in comparison with that of hydrogen peroxide. These results suggest that we can uniformly estimate various physicochemical dynamics of reactive oxygen species against membrane lipids.
Electron scattering from tetrahydrofuran
International Nuclear Information System (INIS)
Fuss, M C; Sanz, A G; García, G; Muñoz, A; Oller, J C; Blanco, F; Do, T P T; Brunger, M J; Almeida, D; Limão-Vieira, P
2012-01-01
Electron scattering from Tetrahydrofuran (C 4 H 8 O) was investigated over a wide range of energies. Following a mixed experimental and theoretical approach, total scattering, elastic scattering and ionization cross sections as well as electron energy loss distributions were obtained.
International Nuclear Information System (INIS)
Doll, P.
1990-02-01
Neutron-proton scattering as fundamental interaction process below and above hundred MeV is discussed. Quark model inspired interactions and phenomenological potential models are described. The seminar also indicates the experimental improvements for achieving new precise scattering data. Concluding remarks indicate the relevance of nucleon-nucleon scattering results to finite nuclei. (orig.) [de
Home Page | Facilities | Reference | Software | Conferences | Announcements | Mailing Lists Neutron Scattering Banner Neutron Scattering Software A new portal for neutron scattering has just been established sets KUPLOT: data plotting and fitting software ILL/TAS: Matlab probrams for analyzing triple axis data
International Nuclear Information System (INIS)
Lovesey, S.W.
1987-05-01
The report reviews, at an introductory level, the theory of photon scattering from condensed matter. Magnetic scattering, which arises from first-order relativistic corrections to the Thomson scattering amplitude, is treated in detail and related to the corresponding interaction in the magnetic neutron diffraction amplitude. (author)
Roessli, B.; Böni, P.
2000-01-01
The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.
Non-eikonal effects in high-energy scattering IV. Inelastic scattering
International Nuclear Information System (INIS)
Gurvitz, S.A.; Kok, L.P.; Rinat, A.S.
1978-01-01
Amplitudes of inelastically scattered high-energy projections were calculated. In the scattering on 12 C(Tsub(P)=1 GeV) sizeable non-eikonal corrections in diffraction extrema even for relatively small q 2 are demonstrated. At least part of the anomaly in the 3 - distribution may be due to these non-eikonal effects. (B.G.)
Stone, Matthew D; Harvey, Stephen B; Martinez, Michael B; Bach, Ronald R; Nelsestuen, Gary L
2005-04-26
Active site-inhibited blood clotting factor VIIa (fVIIai) binds to tissue factor (TF), a cell surface receptor that is exposed upon injury and initiates the blood clotting cascade. FVIIai blocks binding of the corresponding enzyme (fVIIa) or zymogen (fVII) forms of factor VII and inhibits coagulation. Although several studies have suggested that fVIIai may have superior anticoagulation effects in vivo, a challenge for use of fVIIai is cost of production. This study reports the properties of dimeric forms of fVIIai that are cross-linked through their active sites. Dimeric wild-type fVIIai was at least 75-fold more effective than monomeric fVIIai in blocking fVIIa association with TF. The dimer of a mutant fVIIai with higher membrane affinity was 1600-fold more effective. Anticoagulation by any form of fVIIai differed substantially from agents such as heparin and showed a delayed mode of action. Coagulation proceeded normally for the first minutes, and inhibition increased as equilibrium binding was established. It is suggested that association of fVIIa(i) with TF in a collision-dependent reaction gives equal access of inhibitor and enzyme to TF. Assembly was not influenced by the higher affinity and slower dissociation of the dimer. As a result, anticoagulation was delayed until the reaction reached equilibrium. Properties of different dissociation experiments suggested that dissociation of fVIIai from TF occurred by a two-step mechanism. The first step was separation of TF-fVIIa(i) while both proteins remained bound to the membrane, and the second step was dissociation of the fVIIa(i) from the membrane. These results suggest novel actions of fVIIai that distinguish it from most of the anticoagulants that block later steps of the coagulation cascade.
Sharma, Kiran K; Razskazovskiy, Yuriy; Purkayastha, Shubhadeep; Bernhard, William A
2009-06-11
The question of how NA base sequence influences the yield of DNA strand breaks produced by the direct effect of ionizing radiation was investigated in a series of oligodeoxynucleotides of the form (d(CG)(n))(2) and (d(GC)(n))(2). The yields of free base release from X-irradiated DNA films containing 2.5 waters/nucleotide were measured by HPLC as a function of oligomer length. For (d(CG)(n))(2), the ratio of the Gua yield to Cyt yield, R, was relatively constant at 2.4-2.5 for n = 2-4 and it decreased to 1.2 as n increased from 5 to 10. When Gua was moved to the 5' end, for example going from d(CG)(5) to d(GC)(5), R dropped from 1.9 +/- 0.1 to 1.1 +/- 0.1. These effects are poorly described if the chemistry at the oligomer ends is assumed to be independent of the remainder of the oligomer. A mathematical model incorporating charge transfer through the base stack was derived to explain these effects. In addition, EPR was used to measure the yield of trapped-deoxyribose radicals at 4 K following X-irradiation at 4 K. The yield of free base release was substantially greater, by 50-100 nmol/J, than the yield of trapped-deoxyribose radicals. Therefore, a large fraction of free base release stems from a nonradical intermediate. For this intermediate, a deoxyribose carbocation formed by two one-electron oxidations is proposed. This reaction pathway requires that the hole (electron loss site) transfers through the base stack and, upon encountering a deoxyribose hole, oxidizes that site to form a deoxyribose carbocation. This reaction mechanism provides a consistent way of explaining both the absence of trapped radical intermediates and the unusual dependence of free base release on oligomer length.
Nair, Urmila; Bartsch, Helmut; Nair, Jagadeesan
2004-07-01
In south-east Asia, Taiwan and Papua New Guinea, smoking, alcohol consumption and chewing of betel quid with or without tobacco or areca nut with or without tobacco are the predominant causes of oral cancer. In most areas, betel quid consists of a mixture of areca nut, slaked lime, catechu and several condiments according to taste, wrapped in a betel leaf. Almost all habitual chewers use tobacco with or without the betel quid. In the last few decades, small, attractive and inexpensive sachets of betel quid substitutes have become widely available. Aggressively advertised and marketed, often claimed to be safer products, they are consumed by the very young and old alike, particularly in India, but also among migrant populations from these areas world wide. The product is basically a flavoured and sweetened dry mixture of areca nut, catechu and slaked lime with tobacco (gutkha) or without tobacco (pan masala). These products have been strongly implicated in the recent increase in the incidence of oral submucous fibrosis, especially in the very young, even after a short period of use. This precancerous lesion, which has a high rate of malignant transformation, is extremely debilitating and has no known cure. The use of tobacco with lime, betel quid with tobacco, betel quid without tobacco and areca nut have been classified as carcinogenic to humans. As gutkha and pan masala are mixtures of several of these ingredients, their carcinogenic affect can be surmised. We review evidence that strongly supports causative mechanisms for genotoxicity and carcinogenicity of these substitute products. Although some recent curbs have been put on the manufacture and sale of these products, urgent action is needed to permanently ban gutkha and pan masala, together with the other established oral cancer-causing tobacco products. Further, education to reduce or eliminate home-made preparations needs to be accelerated.
Dinu, M. I.
2017-11-01
The article described the complexation of metal ions with humus substances in natural waters (small lakes). Humus substances as the major biochemical components of natural water have a significant impact on the forms and migration of metals and the toxicity of natural objects. This article presents the results of large-scale chemical experiments: the study of the structural features (zonal aspects) of humus substances extracted from soil and water natural climatic zones (more than 300 objects) in Russia (European Russia and West Siberia); the influence of structural features on the physic-chemical parameters of humus acids and, in particular, on their complexing ability. The functional specifics of humus matter extracted from soils is estimated using spectrometric techniques. The conditional stability constants for Fe(III), Cu(II), Pb(II), Cd(II), Zn(II), Ni(II), Co(II), Mn(II), Cr(III), Ca(II), Mg(II), Sr(II), and Al(III) are experimentally determined with the electrochemical, spectroscopic analysis methods. The activities of metals are classified according to their affinity to humus compounds in soils and water. The determined conditional stability constants of the complexes are tested by model experiments, and it is demonstrated that Fe and Al ions have higher conditional stability constants than the ions of alkali earth metals, Pb, Cu, and Zn. Furthermore, the influence of aluminium ions and iron on the complexation of copper and lead as well as the influence of lead and copper on complexation of cobalt and nickel have been identified. The metal forms in a large number of lakes are calculated basing on the experiments’ results. The main chemical mechanisms of the distribution of metals by forms in the water of the lakes in European Russia and West Siberia are described.
International Nuclear Information System (INIS)
Lamehi-Rachti, Mohammad.
1976-01-01
The Einstein-Podolsky-Rosen paradox is briefly exposed with the Bell theorem on hidden variables and the locality principle. The conditions for an ideal experiment are discussed and the results from γ-γ correlation experiments are given. The principle of an experimental measurement of the spin correlation function predicted by the quantum mechanics theory is derived, new hypotheses to be introduced are discussed. The formula giving the dependence of the counting asymmetry on the spin correlation function, polarimeter analyzing power, and geometric correlation is developed. The principle of a Monte Carlo calculation is also exposed. The experimental device is described with the methods for measuring the subsidiary quantities and experimental results are analyzed [fr
Energy Technology Data Exchange (ETDEWEB)
Sneha, Mahima; Gao, Hong; Zare, Richard N., E-mail: zare@stanford.edu, E-mail: aoiz@quim.ucm.es [Department of Chemistry, Stanford University, Stanford, California 94305 (United States); Jambrina, P. G.; Menéndez, M.; Aoiz, F. J., E-mail: zare@stanford.edu, E-mail: aoiz@quim.ucm.es [Departamento de Quimica Fisica I, Facultad de Quimica, Universidad Complutense de Madrid, Madrid 28040 (Spain)
2016-07-14
Differential cross sections (DCSs) for the H + D{sub 2} → HD(v′ = 4, j′) + D reaction at 3.26 eV collision energy have been measured using the photoloc technique, and the results have been compared with those from quantum and quasiclassical scattering calculations. The quantum mechanical DCSs are in good overall agreement with the experimental measurements. In common with previous results at 1.97 eV, clear interference patterns which appear as fingerlike structures have been found at 3.26 eV but in this case for vibrational states as high as v′ = 4. The oscillatory structure is prominent for low rotational states and progressively disappears as j′ increases. A detailed analysis, similar to that carried out at 1.97 eV, shows that the origin of these structures could be traced to interferences between well defined classical mechanisms. In addition, at this energy, we do not observe the anomalous positive j′–θ trend found for the v′ = 4 manifold at lower collision energies, thus reinforcing our explanation that the anomalous distribution for HD(v′ = 4, j′) at 1.97 eV only takes place for those states associated with low product recoil energies.
Neutron scattering studies of eco-friendly functional materials
International Nuclear Information System (INIS)
Mishra, S.K.; Gupta, M.K.; Mittal, R.; Krishna, P.S.R.; Chaplot, S.L.
2016-01-01
Niobate based materials are environment friendly and appropriate for wide piezoelectric applications due to their piezo-response that is comparable to Pb(Zr Ti)O_3 beyond the technological application, NaNbO_3 has been a rich model system for understanding of mechanisms of structural phase transitions when subject to changes in thermodynamical conditions like: temperature, pressure, and/or composition, particle size and external stimuli like electric/magnetic field etc. In the present work, we report systematic investigation of structural phase transitions with variations in temperature, external pressure and chemical pressure (via compositional modification) using the neutron scattering technique. (author)
Flexural-Phonon Scattering Induced by Electrostatic Gating in Graphene
DEFF Research Database (Denmark)
Gunst, Tue; Kaasbjerg, Kristen; Brandbyge, Mads
2017-01-01
Graphene has an extremely high carrier mobility partly due to its planar mirror symmetry inhibiting scattering by the highly occupied acoustic flexural phonons. Electrostatic gating of a graphene device can break the planar mirror symmetry, yielding a coupling mechanism to the flexural phonons......-limiting factor, and show how the carrier density and temperature scaling of the mobility depends on the electrostatic environment. Our findings may explain the high deformation potential for in-plane acoustic phonons extracted from experiments and, furthermore, suggest a direct relation between device symmetry...
Material science and neutron scattering
International Nuclear Information System (INIS)
1983-01-01
Neutron scattering experiments complete and extend the condensed matter studies made with X and gamma rays. Then story show a permanent evolution of the instrumentation, methods and experimental techniques to improve the result quality. This is more especially important as neutron sources are weaker than photon and electron sources. Progress in this research domain is due, in most part, to discovery and development of materials for the different measurement device components [fr
Electron scattering by hydrogen atoms
International Nuclear Information System (INIS)
Fujii, D.H.
1981-02-01
A variational method to calculate the differential cross section of the electron-hydrogen atom scattering process is presented. The second Born approximation is calculated, through a variational calculation using the energy and electronic charge simultaneously as parameters, in order to calculate the differential cross section which is written in a fractional form according to the Schwinger variational principle. Effects due to the electron change are included in the calculations. (L.C.) [pt
Inelastic scattering of fast electrons by crystals
International Nuclear Information System (INIS)
Allen, L.J.; Josefsson, T.W.
1995-01-01
Generalized fundamental equations for electron diffraction in crystals, which include the effect of inelastic scattering described by a nonlocal interaction, are derived. An expression is obtained for the cross section for any specific type of inelastic scattering (e.g. inner-shell ionization, Rutherford backscattering). This result takes into account all other (background) inelastic scattering in the crystal leading to absorption from the dynamical Bragg-reflected beams, in practice mainly due to thermal diffuse scattering. There is a contribution to the cross section from all absorbed electrons, which form a diffuse background, as well as from the dynamical electrons. The approximations involved, assuming that the interactions leading to inelastic scattering can be described by a local potential are discussed, together with the corresponding expression for the cross section. It is demonstrated by means of an example for K-shell electron energy loss spectroscopy that nonlocal effects can be significant. 47 refs., 4 figs
Quantum scattering theory on the momentum lattice
International Nuclear Information System (INIS)
Rubtsova, O. A.; Pomerantsev, V. N.; Kukulin, V. I.
2009-01-01
A new approach based on the wave-packet continuum discretization method recently developed by the present authors for solving quantum-mechanical scattering problems for atomic and nuclear scattering processes and few-body physics is described. The formalism uses the complete continuum discretization scheme in terms of the momentum stationary wave-packet basis, which leads to formulation of the scattering problem on a lattice in the momentum space. The solution of the few-body scattering problem can be found in the approach from linear matrix equations with nonsingular matrix elements, averaged on energy over lattice cells. The developed approach is illustrated by the solution of numerous two- and three-body scattering problems with local and nonlocal potentials below and well above the three-body breakup threshold.
Sum rules in classical scattering
International Nuclear Information System (INIS)
Bolle, D.; Osborn, T.A.
1981-01-01
This paper derives sum rules associated with the classical scattering of two particles. These sum rules are the analogs of Levinson's theorem in quantum mechanics which provides a relationship between the number of bound-state wavefunctions and the energy integral of the time delay of the scattering process. The associated classical relation is an identity involving classical time delay and an integral over the classical bound-state density. We show that equalities between the Nth-order energy moment of the classical time delay and the Nth-order energy moment of the classical bound-state density hold in both a local and a global form. Local sum rules involve the time delay defined on a finite but otherwise arbitrary coordinate space volume S and the bound-state density associated with this same region. Global sum rules are those that obtain when S is the whole coordinate space. Both the local and global sum rules are derived for potentials of arbitrary shape and for scattering in any space dimension. Finally the set of classical sum rules, together with the known quantum mechanical analogs, are shown to provide a unified method of obtaining the high-temperature expansion of the classical, respectively the quantum-mechanical, virial coefficients
Towards a nonpotential scattering theory
International Nuclear Information System (INIS)
Mignani, R.
1985-01-01
We present a formal approach to nonpotential scattering theory (i.e. scattering under unrestricted nonlocal non-Hamiltonian forces), based on the generalization of the concept of scattering matrix (and related topics) to the Lie-isotopic and Lie-admissible case. In the time-dependent formalism, the main taks is the determination of the evolution operator, from which the S matrix is found as a double infinite limit. The study of time-development operators is carried out in detail in the isotopic case, and involves the isotopic generalizations of Moller wave operators, in- and out-states, and temporal (retarded and advanced) propagators. We give also expansion techniques for the S matrix, which extend to the Lie-isotopic formulation the Feynman-Dyson perturbation series, the Magnus expansion, and the Wei-Norman theorem. In the time-independent approach, we solve the isotopic Schroedinger eigenvalue equation by exploiting the properties of isotopic Green operators, Lippmann-Schwinger equations, and incoming and outgoing states, which turn out to be suitable generalizations of the conventional ones. The changes in cross sections due to nonpotential forces are explicitly worked out in some simple cases. A purely algebraic approach to nonpotential scattering, essentially based on the properties of the isowave operators, is presented. The Lie-admissible formulation of the main results is briefly outlined
Antiproton-Proton Glory Scattering
2002-01-01
This experiment measures @*p and K|-p backwards scattering between 8 and 16 GeV/c in the Omega spectrometer using the S1 beam, with sensitivities of several events per nanobarn. The mechanism responsible for backward scattering in channels not mediated by particle exchange is not understood, and could be almost energy-independent glory scattering, especially since relatively high cross sections of 190~(@*p) and 120~(K|-p)nb have been measured earlier at 5~GeV/c. @p|-p backwards scattering is measured for monitoring purposes. The trigger requires a forward particle of momentum close to the beam momentum. Absence of light in the two forward Cerenkov counters indicates that the particle is a proton. Combinations of an incident @p|- and an outgoing K|+, or an incident K|- or @* and an outgoing @p|+, cover the following byproducts: @*p~@A~@p|+@p|- which is an (allowed) baryon exchange reaction, and the exotic exchange reactions @p|-p~@A~K|+Y K|-p~@A~@p|+Y|-, where Y|- may be the @S|- or the Y*|-(1385).
Electromagnetic and gravitational scattering at Planckian energies
International Nuclear Information System (INIS)
Das, S.; Majumdar, P.
1994-11-01
The scattering of pointlike particles at very large center of mass energies and fixed low momentum transfers, occurring due to both their electromagnetic and gravitational interactions is re-examined in the particular case when one of the particles carries magnetic charge. At Planckian center-of-mass energies, when gravitational dominance is normally expected, the presence of magnetic charge is shown to produce dramatic modifications to the scattering cross section as well as to the holomorphic structure of the scattering amplitude. (author). 20 refs
Neutron scattering studies of solid electrolytes
International Nuclear Information System (INIS)
Shapiro, S.M.
1976-01-01
The role which neutron scattering can play in determining the nature of the disorder and the conducting mechanism in the solid electrolytes is discussed. First, some of the general formalism for elastic and inelastic neutron scattering is reviewed, and the quantities which can be measured are pointed out. Then the application of neutron scattering to the studies of three different problems is examined; the anion disorder in the fluorite system, the dynamical behavior in beta-alumina, and the cation diffusion in αAgI are discussed. 8 figures
Variation of entanglement entropy in scattering process
Energy Technology Data Exchange (ETDEWEB)
Seki, Shigenori, E-mail: sigenori@hanyang.ac.kr [Research Institute for Natural Science, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, I.Y., E-mail: inyongpark05@gmail.com [Department of Applied Mathematics, Philander Smith College, Little Rock, AR 72223 (United States); Sin, Sang-Jin, E-mail: sjsin@hanyang.ac.kr [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of)
2015-04-09
In a scattering process, the final state is determined by an initial state and an S-matrix. We focus on two-particle scattering processes and consider the entanglement between these particles. For two types initial states, i.e., an unentangled state and an entangled one, we calculate perturbatively the change of entanglement entropy from the initial state to the final one. Then we show a few examples in a field theory and in quantum mechanics.
Scattering with polarized neutrons
International Nuclear Information System (INIS)
Schweizer, J.
2007-01-01
In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)
Neutron scattering and magnetism
International Nuclear Information System (INIS)
Mackintosh, A.R.
1983-01-01
Those properties of the neutron which make it a unique tool for the study of magnetism are described. The scattering of neutrons by magnetic solids is briefly reviewed, with emphasis on the information on the magnetic structure and dynamics which is inherent in the scattering cross-section. The contribution of neutron scattering to our understanding of magnetic ordering, excitations and phase transitions is illustrated by experimental results on a variety of magnetic crystals. (author)
Stationary theory of scattering
International Nuclear Information System (INIS)
Kato, T.
1977-01-01
A variant of the stationary methods is described, and it is shown that it is useful in a wide range of problems, including scattering, by long-range potentials, two-space scattering, and multichannel scattering. The method is based on the notion of spectral forms. The paper is restricted to the simplest case of continuous spectral forms defined on a Banach space embedded in the basic Hilbert space. (P.D.)
Introduction to neutron scattering
Energy Technology Data Exchange (ETDEWEB)
Fischer, W E [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1996-11-01
We give here an introduction to the theoretical principles of neutron scattering. The relationship between scattering- and correlation-functions is particularly emphasized. Within the framework of linear response theory (justified by the weakness of the basic interaction) the relation between fluctuation and dissipation is discussed. This general framework explains the particular power of neutron scattering as an experimental method. (author) 4 figs., 4 refs.
International Nuclear Information System (INIS)
Futterman, J.A.H.; Handler, F.A.; Matzner, R.A.
1987-01-01
This book provides a comprehensive treatment of the propagation of waves in the presence of black holes. While emphasizing intuitive physical thinking in their treatment of the techniques of analysis of scattering, the authors also include chapters on the rigorous mathematical development of the subject. Introducing the concepts of scattering by considering the simplest, scalar wave case of scattering by a spherical (Schwarzschild) black hole, the book then develops the formalism of spin weighted spheroidal harmonics and of plane wave representations for neutrino, electromagnetic, and gravitational scattering. Details and results of numerical computations are given. The techniques involved have important applications (references are given) in acoustical and radar imaging
Wu Ta You
1962-01-01
This volume addresses the broad formal aspects and applications of the quantum theory of scattering in atomic and nuclear collisions. An encyclopedic source of pioneering work, it serves as a text for students and a reference for professionals in the fields of chemistry, physics, and astrophysics. The self-contained treatment begins with the general theory of scattering of a particle by a central field. Subsequent chapters explore particle scattering by a non-central field, collisions between composite particles, the time-dependent theory of scattering, and nuclear reactions. An examinati
Cross plane scattering correction
International Nuclear Information System (INIS)
Shao, L.; Karp, J.S.
1990-01-01
Most previous scattering correction techniques for PET are based on assumptions made for a single transaxial plane and are independent of axial variations. These techniques will incorrectly estimate the scattering fraction for volumetric PET imaging systems since they do not take the cross-plane scattering into account. In this paper, the authors propose a new point source scattering deconvolution method (2-D). The cross-plane scattering is incorporated into the algorithm by modeling a scattering point source function. In the model, the scattering dependence both on axial and transaxial directions is reflected in the exponential fitting parameters and these parameters are directly estimated from a limited number of measured point response functions. The authors' results comparing the standard in-plane point source deconvolution to the authors' cross-plane source deconvolution show that for a small source, the former technique overestimates the scatter fraction in the plane of the source and underestimate the scatter fraction in adjacent planes. In addition, the authors also propose a simple approximation technique for deconvolution
Neutron scattering and models: Silver
International Nuclear Information System (INIS)
Smith, A.B.
1996-07-01
Differential neutron elastic-scattering cross sections of elemental silver were measured from 1.5 → 10 MeV at ∼ 100 keV intervals up to 3 MeV, at ∼ 200 keV intervals from 3 → 4 MeV, and at ∼ 500 keV intervals above 4 MeV. At ≤ 4 MeV the angular range of the measurements was ∼ 20 0 → 160 0 with 10 measured values below 3 MeV and 20 from 3 → 4 MeV at each incident energy. Above 4 MeV ≥ 40 scattering angles were used distributed between ∼ 17 0 and 16 0 All of the measured elastic distributions included some contributions due to inelastic scattering. Below 4 MeV the measurements determined cross sections for ten inelastically-scattered neutron groups corresponding to observed excitations of 328 ± 13, 419 ± 50, 748 ± 25, 908 ± 26, 115 ± 38, 1286 ± 25, 1507 ± 20, 1632 ± 30, 1835 ± 20 and 1944 ± 26 keV. All of these inelastic groups probably were composites of contributions from the two isotopes 107 Ag and 109 Ag. The experimental results were interpreted in terms of the spherical optical model and of rotational and vibrational coupled-channels models, and physical implications are discussed. In particular, the neutron-scattering results are consistent with a ground-state rotational band with a quadrupole deformation Β 2 = 0.20 ± ∼ 10% for both of the naturally-occurring silver isotopes
Rost, S.; Earle, P.S.
2010-01-01
We detect seismic scattering from the core-mantle boundary related to the phase PKKP (PK. KP) in data from small aperture seismic arrays in India and Canada. The detection of these scattered waves in data from small aperture arrays is new and allows a better characterization of the fine-scale structure of the deep Earth especially in the southern hemisphere. Their slowness vector is determined from array processing allowing location of the heterogeneities at the core-mantle boundary using back-projection techniques through 1D Earth models. We identify strong scattering at the core-mantle boundary (CMB) beneath the Caribbean, Patagonia and the Antarctic Peninsula as well as beneath southern Africa. An analysis of the scattering regions relative to sources and receivers indicates that these regions represent areas of increased scattering likely due to increased heterogeneities close to the CMB. The 1. Hz array data used in this study is most sensitive to heterogeneity with scale lengths of about 10. km. Given the small size of the scatterers, a chemical origin of the heterogeneities is likely. By comparing the location of the fine-scale heterogeneity to geodynamical models and tomographic images, we identify different scattering mechanisms in regions related to subduction (Caribbean and Patagonia) and dense thermo chemical piles (Southern Africa). ?? 2010 Elsevier B.V.
Energy Technology Data Exchange (ETDEWEB)
Tsytovich, Vadim, E-mail: tsytov@lpi.ru [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilova str. 38, Moscow 119991 (Russian Federation); Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Gusein-zade, Namik; Ignatov, Alexander [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilova str. 38, Moscow 119991 (Russian Federation); Medicobiologic Faculty, Pirogov Russian National Research Medical University, Moscow (Russian Federation)
2015-07-15
Dust structuring is a natural and universal process in complex plasmas. The scattering of electromagnetic waves by dust structures is governed by the factor of coherency, i.e., the total number of coherent electrons in a single structure. In the present paper, we consider how the factor of coherency changes due to additional pulse electron heating and show that it obeys a hysteresis. After the end of the pulse heating, the scattering intensity differs substantially from that before heating. There are three necessary conditions for scattering hysteresis: first, the radiation wavelength should be larger than the pattern (structure) size; second, the total number of coherent electrons confined by the structure should be large; and third, the heating pulse duration should be shorter than the characteristic time of dust structure formation. We present the results of numerical calculations using existing models of self-consistent dust structures with either positively or negatively charged dust grains. It is shown that, depending on the grain charge and the ionization rate, two types of hysteresis are possible: one with a final increase of the scattering and the other with a final decrease of the scattering. It is suggested that the hysteresis of coherent scattering can be used as a tool in laboratory experiments and that it can be a basic mechanism explaining the observed hysteresis in radar scattering by noctilucent clouds during active experiments on electron heating in mesosphere.
Complex scattering dynamics and the quantum Hall effects
International Nuclear Information System (INIS)
Trugman, S.A.
1994-01-01
We review both classical and quantum potential scattering in two dimensions in a magnetic field, with applications to the quantum Hall effect. Classical scattering is complex, due to the approach of scattering states to an infinite number of dynamically bound states. Quantum scattering follows the classical behavior rather closely, exhibiting sharp resonances in place of the classical bound states. Extended scatterers provide a quantitative explanation for the breakdown of the QHE at a comparatively small Hall voltage as seen by Kawaji et al., and possibly for noise effects
Quantum scattering at low energies
DEFF Research Database (Denmark)
Derezinski, Jan; Skibsted, Erik
For a class of negative slowly decaying potentials, including with , we study the quantum mechanical scattering theory in the low-energy regime. Using modifiers of the Isozaki--Kitada type we show that scattering theory is well behaved on the {\\it whole} continuous spectrum of the Hamiltonian......, including the energy . We show that the --matrices are well-defined and strongly continuous down to the zero energy threshold. Similarly, we prove that the wave matrices and generalized eigenfunctions are norm continuous down to the zero energy if we use appropriate weighted spaces. These results are used...... from positive energies to the limiting energy . This change corresponds to the behaviour of the classical orbits. Under stronger conditions we extract the leading term of the asymptotics of the kernel of at its singularities; this leading term defines a Fourier integral operator in the sense...
Scattering characteristics from porous silicon
Directory of Open Access Journals (Sweden)
R. Sabet-Dariani
2000-12-01
Full Text Available Porous silicon (PS layers come into existance as a result of electrochemical anodization on silicon. Although a great deal of research has been done on the formation and optical properties of this material, the exact mechanism involved is not well-understood yet. In this article, first, the optical properties of silicon and porous silicon are described. Then, previous research and the proposed models about reflection from PS and the origin of its photoluminescence are reveiwed. The reflecting and scattering, absorption and transmission of light from this material, are then investigated. These experiments include,different methods of PS sample preparation their photoluminescence, reflecting and scattering of light determining different characteristics with respect to Si bulk.
Theory of Graphene Raman Scattering.
Heller, Eric J; Yang, Yuan; Kocia, Lucas; Chen, Wei; Fang, Shiang; Borunda, Mario; Kaxiras, Efthimios
2016-02-23
Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly.
Polarization transfer in inelastic scattering
International Nuclear Information System (INIS)
Moss, J.M.
1980-01-01
Polarization transfer experiments are now feasible for inelastic scattering experiments on complex nuclei. Experiments thus far have dealt with the spin-flip probability; this observable is sensitive to the action of spin-spin and tensor forces in inelastic scattering. Spin-flip probabilities at E approx. 40 MeV in isoscalar transitions in 12 C(12.71 MeV) and 15 O(8.89 MeV) show considerable deviation from DWBA-shell model predictions; this deviation indicates evidence for more complex reaction mechanisms. Experiments at intermediate energies will soon be possible and will yield data of much higher precision than is possible at lower (E < 100 MeV) energies. These experiments hold exciting promise in such areas as nuclear critical opalescence. 7 figures, 1 table
Compton scatter correction for planner scintigraphic imaging
Energy Technology Data Exchange (ETDEWEB)
Vaan Steelandt, E; Dobbeleir, A; Vanregemorter, J [Algemeen Ziekenhuis Middelheim, Antwerp (Belgium). Dept. of Nuclear Medicine and Radiotherapy
1995-12-01
A major problem in nuclear medicine is the image degradation due to Compton scatter in the patient. Photons emitted by the radioactive tracer scatter in collision with electrons of the surrounding tissue. Due to the resulting loss of energy and change in direction, the scattered photons induce an object dependant background on the images. This results in a degradation of the contrast of warm and cold lesions. Although theoretically interesting, most of the techniques proposed in literature like the use of symmetrical photopeaks can not be implemented on the commonly used gamma camera due to the energy/linearity/sensitivity corrections applied in the detector. A method for a single energy isotope based on existing methods with adjustments towards daily practice and clinical situations is proposed. It is assumed that the scatter image, recorded from photons collected within a scatter window adjacent to the photo peak, is a reasonable close approximation of the true scatter component of the image reconstructed from the photo peak window. A fraction `k` of the image using the scatter window is subtracted from the image recorded in the photo peak window to produce the compensated image. The principal matter of the method is the right value for the factor `k`, which is determined in a mathematical way and confirmed by experiments. To determine `k`, different kinds of scatter media are used and are positioned in different ways in order to simulate a clinical situation. For a secondary energy window from 100 to 124 keV below a photo peak window from 126 to 154 keV, a value of 0.7 is found. This value has been verified using both an antropomorph thyroid phantom and the Rollo contrast phantom.
Directory of Open Access Journals (Sweden)
Masoud Rabbani
2016-06-01
Full Text Available In the competitive business world, applying a reliable and powerful mechanism to support decision makers in manufacturing companies and helping them save time by considering varieties of effective factors is an inevitable issue. Advanced Available-to-Promise is a perfect tool to design and perform such a mechanism. In this study, this mechanism which is compatible with the Make-to-Forecast production systems is presented. The ability to distinguish between batch mode and real-time mode advanced available-to-promise is one of the unique superiorities of the proposed model. We also try to strengthen this mechanism by integrating the inventory allocation and job shop scheduling by considering due dates and weighted earliness/tardiness cost that leads to more precise decisions. A mixed integer programming (MIP model and a heuristic algorithm according to its disability to solve large size problems are presented. The designed experiments and the obtained results have proved the efficiency of the proposed heuristic method.
Dual scattering foil design for poly-energetic electron beams
International Nuclear Information System (INIS)
Kainz, K K; Antolak, J A; Almond, P R; Bloch, C D; Hogstrom, K R
2005-01-01
The laser wakefield acceleration (LWFA) mechanism can accelerate electrons to energies within the 6-20 MeV range desired for therapy application. However, the energy spectrum of LWFA-generated electrons is broad, on the order of tens of MeV. Using existing laser technology, the therapeutic beam might require a significant energy spread to achieve clinically acceptable dose rates. The purpose of this work was to test the assumption that a scattering foil system designed for a mono-energetic beam would be suitable for a poly-energetic beam with a significant energy spread. Dual scattering foil systems were designed for mono-energetic beams using an existing analytical formalism based on Gaussian multiple-Coulomb scattering theory. The design criterion was to create a flat beam that would be suitable for fields up to 25 x 25 cm 2 at 100 cm from the primary scattering foil. Radial planar fluence profiles for poly-energetic beams with energy spreads ranging from 0.5 MeV to 6.5 MeV were calculated using two methods: (a) analytically by summing beam profiles for a range of mono-energetic beams through the scattering foil system, and (b) by Monte Carlo using the EGS/BEAM code. The analytic calculations facilitated fine adjustments to the foil design, and the Monte Carlo calculations enabled us to verify the results of the analytic calculation and to determine the phase-space characteristics of the broadened beam. Results showed that the flatness of the scattered beam is fairly insensitive to the width of the input energy spectrum. Also, results showed that dose calculated by the analytical and Monte Carlo methods agreed very well in the central portion of the beam. Outside the useable field area, the differences between the analytical and Monte Carlo results were small but significant, possibly due to the small angle approximation. However, these did not affect the conclusion that a scattering foil system designed for a mono-energetic beam will be suitable for a poly
International Nuclear Information System (INIS)
Kuehnelt, H.
1975-01-01
We discuss a few properties of scattering amplitudes proved within the framework of the field theory and their significance in the derivation of quantitative statements. The state of the boundaries for the scattering lengths is to be especially discussed as well as the question as to how far it is possible to exclude various solutions from phase displacement analyses. (orig./LH) [de
Modelling Hyperboloid Sound Scattering
DEFF Research Database (Denmark)
Burry, Jane; Davis, Daniel; Peters, Brady
2011-01-01
The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...... both physical and digital models at three distinct scales. The results suggest hyperboloid geometry, while difficult to fabricate, facilitates sound scattering....
Donne, A. J. H.
1996-01-01
Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is
Concentric layered Hermite scatterers
Astheimer, Jeffrey P.; Parker, Kevin J.
2018-05-01
The long wavelength limit of scattering from spheres has a rich history in optics, electromagnetics, and acoustics. Recently it was shown that a common integral kernel pertains to formulations of weak spherical scatterers in both acoustics and electromagnetic regimes. Furthermore, the relationship between backscattered amplitude and wavenumber k was shown to follow power laws higher than the Rayleigh scattering k2 power law, when the inhomogeneity had a material composition that conformed to a Gaussian weighted Hermite polynomial. Although this class of scatterers, called Hermite scatterers, are plausible, it may be simpler to manufacture scatterers with a core surrounded by one or more layers. In this case the inhomogeneous material property conforms to a piecewise continuous constant function. We demonstrate that the necessary and sufficient conditions for supra-Rayleigh scattering power laws in this case can be stated simply by considering moments of the inhomogeneous function and its spatial transform. This development opens an additional path for construction of, and use of scatterers with unique power law behavior.
Decomposition in aluminium alloys: diffuse scattering and crystal modelling
International Nuclear Information System (INIS)
Aslam-Malik, A.
1995-01-01
In the present study the microstructure of metastable precipitates in Al-Ag and Al-Cu, so called pre-precipitates or Guinier-Preston (GP) zones, was investigated. In both systems important aspects of the microstructure are still controversially discussed. In Al-Ag two forms of GP zones are suggested; depending on the aging temperatures above or below about 443 K, ε- or η-zones should evolve. Differences between these two types of zones may be due to differences in internal order and/or composition. In Al-Cu the characterization of GP I zones is difficult because of the strong atomic displacements around the zones. The proper separation of short-range order and displacement scattering within a diffuse scattering experiment is still under discussion. The technique used to determine the short-range order in both alloys was diffuse scattering with neutrons and X-rays. To separate short-range order and displacement scattering, the methods of Georgopoulos-Cohen (X-ray scattering) and Borie-Sparks (neutron scattering) were used. Of main importance is the optimization of the scattering contrast and thus the scattering contribution due to short-range order. Short-range order scattering is rationalized in terms of pair correlations. Crystals may subsequently be modelled to visualize the microstructure. The Al-Ag system was investigated by diffuse X-ray wide-angle scattering and small-angle neutron scattering. The small-angle neutron scattering measurement was necessary since the GP zones in Al-Ag are almost spherical and the main scattering contribution is found close to the origin of reciprocal space. The small-angle scattering is not that important in the case of Al-Cu because the main scattering extends along (100) owing to the planar character of the GP I zones on (100) lattice planes. (author) 24 figs., 10 tabs., refs
Measurements of computed tomography radiation scatter
International Nuclear Information System (INIS)
Van Every, B.; Petty, R.J.
1992-01-01
This paper describes the measurement of scattered radiation from a computed tomography (CT) scanner in a clinical situation and compares the results with those obtained from a CT performance phantom and with data obtained from CT manufacturers. The results are presented as iso-dose contours. There are significant differences between the data obtained and that supplied by manufacturers, both in the shape of the iso-dose contours and in the nominal values. The observed scatter in a clinical situation (for an abdominal scan) varied between 3% and 430% of the manufacturers' stated values, with a marked reduction in scatter noted a the head and feet of the patient. These differences appear to be due to the fact that manufacturers use CT phantoms to obtain scatter data and these phantoms do not provide the same scatter absorption geometry as patients. CT scatter was observed to increase as scan field size and slice thickness increased, whilst there was little change in scatter with changes in gantry tilt and table slew. Using the iso-dose contours, the orientation of the CT scanner can be optimised with regard to the location and shielding requirements of doors and windows. Additionally, the positioning of staff who must remain in the room during scanning can be optimised to minimise their exposure. It is estimated that the data presented allows for realistic radiation protection assessments to be made. 13 refs., 5 tabs., 6 figs
Introductory theory of neutron scattering
International Nuclear Information System (INIS)
Gunn, J.M.F.
1986-12-01
The paper comprises a set of six lecture notes which were delivered to the summer school on 'Neutron Scattering at a pulsed source', Rutherford Laboratory, United Kingdom, 1986. The lectures concern the physical principles of neutron scattering. The topics of the lectures include: diffraction, incoherent inelastic scattering, connection with the Schroedinger equation, magnetic scattering, coherent inelastic scattering, and surfaces and neutron optics. (UK)
Diffuse scattering of neutrons
International Nuclear Information System (INIS)
Novion, C.H. de.
1981-02-01
The use of neutron scattering to study atomic disorder in metals and alloys is described. The diffuse elastic scattering of neutrons by a perfect crystal lattice leads to a diffraction spectrum with only Bragg spreads. the existence of disorder in the crystal results in intensity and position modifications to these spreads, and above all, to the appearance of a low intensity scatter between Bragg peaks. The elastic scattering of neutrons is treated in this text, i.e. by measuring the number of scattered neutrons having the same energy as the incident neutrons. Such measurements yield information on the static disorder in the crystal and time average fluctuations in composition and atomic displacements [fr
Inelastic Light Scattering Processes
Fouche, Daniel G.; Chang, Richard K.
1973-01-01
Five different inelastic light scattering processes will be denoted by, ordinary Raman scattering (ORS), resonance Raman scattering (RRS), off-resonance fluorescence (ORF), resonance fluorescence (RF), and broad fluorescence (BF). A distinction between fluorescence (including ORF and RF) and Raman scattering (including ORS and RRS) will be made in terms of the number of intermediate molecular states which contribute significantly to the scattered amplitude, and not in terms of excited state lifetimes or virtual versus real processes. The theory of these processes will be reviewed, including the effects of pressure, laser wavelength, and laser spectral distribution on the scattered intensity. The application of these processes to the remote sensing of atmospheric pollutants will be discussed briefly. It will be pointed out that the poor sensitivity of the ORS technique cannot be increased by going toward resonance without also compromising the advantages it has over the RF technique. Experimental results on inelastic light scattering from I(sub 2) vapor will be presented. As a single longitudinal mode 5145 A argon-ion laser line was tuned away from an I(sub 2) absorption line, the scattering was observed to change from RF to ORF. The basis, of the distinction is the different pressure dependence of the scattered intensity. Nearly three orders of magnitude enhancement of the scattered intensity was measured in going from ORF to RF. Forty-seven overtones were observed and their relative intensities measured. The ORF cross section of I(sub 2) compared to the ORS cross section of N2 was found to be 3 x 10(exp 6), with I(sub 2) at its room temperature vapor pressure.
Rayleigh scattering from ions near threshold
International Nuclear Information System (INIS)
Roy, S.C.; Gupta, S.K.S.; Kissel, L.; Pratt, R.H.
1988-01-01
Theoretical studies of Rayleigh scattering of photons from neon atoms with different degrees of ionization, for energies both below and above the K-edges of the ions, are presented. Some unexpected structures both in Rayleigh scattering and in photoionization from neutral and weakly ionized atoms, very close to threshold, have been reported. It has recently been realized that some of the predicted structures may have a nonphysical origin and are due to the limitation of the independent-particle model and also to the use of a Coulombic Latter tail. Use of a K-shell vacancy potential - in which an electron is assumed to be removed from the K-shell - in calculating K-shell Rayleigh scattering amplitudes removes some of the structure effects near threshold. We present in this work a discussion of scattering angular distributions and total cross sections, obtained utilizing vacancy potentials, and compare these predictions with those previously obtained in other potential model. (author) [pt
Turbulence Scattering of High Harmonic Fast Waves
International Nuclear Information System (INIS)
M. Ono; J. Hosea; B. LeBlanc; J. Menard; C.K. Phillips; R. Wilson; P. Ryan; D. Swain; J. Wilgen; S. Kubota; and T.K. Mau
2001-01-01
Effect of scattering of high-harmonic fast-magnetosonic waves (HHFW) by low-frequency plasma turbulence is investigated. Due to the similarity of the wavelength of HHFW to that of the expected low-frequency turbulence in the plasma edge region, the scattering of HHFW can become significant under some conditions. The scattering probability increases with the launched wave parallel-phase-velocity as the location of the wave cut-off layer shifts toward the lower density edge. The scattering probability can be reduced significantly with higher edge plasma temperature, steeper edge density gradient, and magnetic field. The theoretical model could explain some of the HHFW heating observations on the National Spherical Torus Experiment (NSTX)
Light scattering in glass-ceramics
International Nuclear Information System (INIS)
Hendy, S.C.
2002-01-01
Full text: Glass-ceramic materials with microstructures comprised of dispersed nanocrystallites in a residual glass matrix show promise for many new technological applications. In particular, transparent glass-ceramics offer low thermal expansion and stability, in addition to the prospect of novel non-linear optical properties that can arise from the nanocrystallites. Good transparency requires low optical scattering and low atomic absorption. Light scattering in the glass-ceramic arises primarily from the glass-crystallite interface. The attenuation due to scattering (turbidity) will depend upon the difference in refractive index of the two phases and the size and distribution of nanocrystallites in the glass. Here we consider models of glass-ceramic structure formation and look at scattering in these model structures to increase our understanding of the transparency of glass-ceramics
Cloaking through cancellation of diffusive wave scattering
Farhat, Mohamed
2016-08-10
A new cloaking mechanism, which makes enclosed objects invisible to diffusive photon density waves, is proposed. First, diffusive scattering from a basic core-shell geometry, which represents the cloaked structure, is studied. The conditions of scattering cancellation in a quasi-static scattering regime are derived. These allow for tailoring the diffusivity constant of the shell enclosing the object so that the fields scattered from the shell and the object cancel each other. This means that the photon flow outside the cloak behaves as if the cloaked object were not present. Diffusive light invisibility may have potential applications in hiding hot spots in infrared thermography or tissue imaging. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
Sechopoulos, Ioannis; Bliznakova, Kristina; Fei, Baowei
2013-10-01
To analyze the frequency domain characteristics of the signal in mammography images and breast tomosynthesis projections with patient tissue texture due to detected scattered x-rays. Acquisitions of x-ray projection images of 19 different patient breasts were simulated using previously acquired volumetric patient images. Acquisition of these images was performed with a dedicated breast CT prototype system, and the images were classified into voxels representing skin, adipose, and glandular tissue with a previously validated automated algorithm. The classified three dimensional images then underwent simulated mechanical compression representing that which is performed during acquisition of mammography and breast tomosynthesis images. The acquisition of projection images of each patient breast was simulated using Monte Carlo methods with each simulation resulting in two images: one of the primary (non-scattered) signal and one of the scatter signal. To analyze the scatter signal for both mammography and breast tomosynthesis, two projections images of each patient breast were simulated, one with the x-ray source positioned at 0° (mammography and central tomosynthesis projection) and at 30° (wide tomosynthesis projection). The noise power spectra (NPS) for both the scatter signal alone and the total signal (primary + scatter) for all images were obtained and the combined results of all patients analyzed. The total NPS was fit to the expected power-law relationship NPS(f) = k/f β and the results were compared with those previously published on the power spectrum characteristics of mammographic texture. The scatter signal alone was analyzed qualitatively and a power-law fit was also performed. The mammography and tomosynthesis projections of three patient breasts were too small to analyze, so a total of 16 patient breasts were analyzed. The values of β for the total signal of the 0° projections agreed well with previously published results. As expected, the scatter
Energy Technology Data Exchange (ETDEWEB)
Mousseau, Joel A. [Univ. of Florida, Gainesville, FL (United States)
2015-01-01
Decades of research in electron-nucleus deep inelastic scattering (DIS) have provided a clear picture of nuclear physics at high momentum transfer. While these effects have been clearly demonstrated by experiment, the theoretical explanation of their origin in some kinematic regions has been lacking. Particularly, the effects in the intermediate regions of Bjorken-x, anti-shadowing and the EMC effect have no universally accepted quantum mechanical explanation. In addition, these effects have not been measured systematically with neutrino-nucleus deep inelastic scattering, due to experiments lacking multiple heavy targets.
Directory of Open Access Journals (Sweden)
Jingjuan Liao
2015-07-01
Full Text Available We developed a polarimetric coherent electromagnetic scattering model for Poyang Lake wetland vegetation. Realistic canopy structures including curved leaves and the lodging situation of the vegetation were taken into account, and the situation at the ground surface was established using an Advanced Integral Equation Model combined with Oh’s 2002 model. This new model can reasonably describe the coherence effect caused by the phase differences of the electromagnetic fields scattered from different particles by different scattering mechanisms. We obtained good agreement between the modeling results and C-band data from the Radarsat-2 satellite. A simulation of scattering from the vegetation in Poyang Lake showed that direct vegetation scattering and the single-ground-bounce mechanism are the dominant scattering mechanisms in the C-band and L-band, while the effects of the double-ground-bounce mechanism are very small. We note that the curvature of the leaves and the lodging characteristics of the vegetation cannot be ignored in the modeling process. Monitoring soil moisture in the Poyang Lake wetland with the C-band data was not feasible because of the density and depth of Poyang Lake vegetation. When the density of Poyang Lake Carex increases, the backscattering coefficient either decreases or remains stable.
Introduction to the theory of thermal neutron scattering
Squires, G L
2012-01-01
Since the advent of the nuclear reactor, thermal neutron scattering has proved a valuable tool for studying many properties of solids and liquids, and research workers are active in the field at reactor centres and universities throughout the world. This classic text provides the basic quantum theory of thermal neutron scattering and applies the concepts to scattering by crystals, liquids and magnetic systems. Other topics discussed are the relation of the scattering to correlation functions in the scattering system, the dynamical theory of scattering and polarisation analysis. No previous knowledge of the theory of thermal neutron scattering is assumed, but basic knowledge of quantum mechanics and solid state physics is required. The book is intended for experimenters rather than theoreticians, and the discussion is kept as informal as possible. A number of examples, with worked solutions, are included as an aid to the understanding of the text.
Light scattering studies at UNICAMP
International Nuclear Information System (INIS)
Luzzi, R.; Cerdeira, H.A.; Salzberg, J.; Vasconcellos, A.R.; Frota Pessoa, S.; Reis, F.G. dos; Ferrari, C.A.; Algarte, C.A.S.; Tenan, M.A.
1975-01-01
Current theoretical studies on light scattering spectroscopy at UNICAMP is presented briefly, such as: inelastic scattering of radiation from a solid state plasma; resonant Ramman scattering; high excitation effects; saturated semiconductors and glasses
Molecular selectivity of graphene-enhanced Raman scattering.
Huang, Shengxi; Ling, Xi; Liang, Liangbo; Song, Yi; Fang, Wenjing; Zhang, Jin; Kong, Jing; Meunier, Vincent; Dresselhaus, Mildred S
2015-05-13
Graphene-enhanced Raman scattering (GERS) is a recently discovered Raman enhancement phenomenon that uses graphene as the substrate for Raman enhancement and can produce clean and reproducible Raman signals of molecules with increased signal intensity. Compared to conventional Raman enhancement techniques, such as surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS), in which the Raman enhancement is essentially due to the electromagnetic mechanism, GERS mainly relies on a chemical mechanism and therefore shows unique molecular selectivity. In this paper, we report graphene-enhanced Raman scattering of a variety of different molecules with different molecular properties. We report a strong molecular selectivity for the GERS effect with enhancement factors varying by as much as 2 orders of magnitude for different molecules. Selection rules are discussed with reference to two main features of the molecule, namely its molecular energy levels and molecular structures. In particular, the enhancement factor involving molecular energy levels requires the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies to be within a suitable range with respect to graphene's Fermi level, and this enhancement effect can be explained by the time-dependent perturbation theory of Raman scattering. The enhancement factor involving the choice of molecular structures indicates that molecular symmetry and substituents similar to that of the graphene structure are found to be favorable for GERS enhancement. The effectiveness of these factors can be explained by group theory and the charge-transfer interaction between molecules and graphene. Both factors, involving the molecular energy levels and structural symmetry of the molecules, suggest that a remarkable GERS enhancement requires strong molecule-graphene coupling and thus effective charge transfer between the molecules and graphene. These conclusions are further
Ultrafast collinear scattering and carrier multiplication in graphene.
Brida, D; Tomadin, A; Manzoni, C; Kim, Y J; Lombardo, A; Milana, S; Nair, R R; Novoselov, K S; Ferrari, A C; Cerullo, G; Polini, M
2013-01-01
Graphene is emerging as a viable alternative to conventional optoelectronic, plasmonic and nanophotonic materials. The interaction of light with charge carriers creates an out-of-equilibrium distribution, which relaxes on an ultrafast timescale to a hot Fermi-Dirac distribution, that subsequently cools emitting phonons. Although the slower relaxation mechanisms have been extensively investigated, the initial stages still pose a challenge. Experimentally, they defy the resolution of most pump-probe setups, due to the extremely fast sub-100 fs carrier dynamics. Theoretically, massless Dirac fermions represent a novel many-body problem, fundamentally different from Schrödinger fermions. Here we combine pump-probe spectroscopy with a microscopic theory to investigate electron-electron interactions during the early stages of relaxation. We identify the mechanisms controlling the ultrafast dynamics, in particular the role of collinear scattering. This gives rise to Auger processes, including charge multiplication, which is key in photovoltage generation and photodetectors.
Coherence effects in radiative scattering
International Nuclear Information System (INIS)
Knoll, J.; Lenk, R.
1993-03-01
The bremsstrahl-production of photons in dense matter is reinvestigated using the example of an exactly solvable quantum mechanical model in one space dimension. Coherence phenomena between successive radiative scatterings among the constituents lead to a modification of the production cross section in the medium relative to the incoherent quasi-free prescription used in kinetic models. Analytic expressions for the correction factor have been derived comparing the quantum rates with the corresponding incoherent quasi-free rates. The result has implications for the kinetic description of all kinds of radiative processes in nucleus-nucleus collisions, both on the level of hadron and parton dynamics. (orig.)
Spin relaxation in quantum dots due to electron exchange with leads.
Vorontsov, A B; Vavilov, M G
2008-11-28
We calculate spin relaxation rates in lateral quantum dot systems due to electron exchange between dots and leads. Using rate equations, we develop a theoretical description of the experimentally observed electric current in the spin blockade regime of double quantum dots. A single expression fits the entire current profile and describes the structure of both the conduction peaks and the suppressed ("valley") region. Extrinsic rates calculated here have to be taken into account for accurate extraction of intrinsic relaxation rates due to the spin-orbit and hyperfine spin scattering mechanisms from spin blockade measurements.
Virtual neutron scattering experiments
DEFF Research Database (Denmark)
Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael
2017-01-01
. In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus......We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering...
Scattering on magnetic monopoles
International Nuclear Information System (INIS)
Petry, H.R.
1980-01-01
The time-dependent scattering theory of charged particles on magnetic monopoles is investigated within a mathematical frame-work, which duely pays attention to the fact that the wavefunctions of the scattered particles are sections in a non-trivial complex line-bundle. It is found that Moeller operators have to be defined in a way which takes into account the peculiar long-range behaviour of the monopole field. Formulas for the scattering matrix and the differential cross-section are derived, and, as a by-product, a momentum space picture for particles, which are described by sections in the underlying complex line-bundle, is presented. (orig.)
Deep inelastic neutron scattering
International Nuclear Information System (INIS)
Mayers, J.
1989-03-01
The report is based on an invited talk given at a conference on ''Neutron Scattering at ISIS: Recent Highlights in Condensed Matter Research'', which was held in Rome, 1988, and is intended as an introduction to the techniques of Deep Inelastic Neutron Scattering. The subject is discussed under the following topic headings:- the impulse approximation I.A., scaling behaviour, kinematical consequences of energy and momentum conservation, examples of measurements, derivation of the I.A., the I.A. in a harmonic system, and validity of the I.A. in neutron scattering. (U.K.)
Zheng, Tingting; Feng, Enduo; Wang, Zhiqiang; Gong, Xueqing; Tian, Yang
2017-10-25
With a burst development of new nanomaterials for plasmon-free surface-enhanced Raman scattering (SERS), the understanding of chemical mechanism (CM) and further applications have become more and more attractive. Herein, a novel SERS platform was specially designed through electrochemical deposition of graphene onto TiO 2 nanoarrays (EG-TiO 2 ). The developed EG-TiO 2 nanocomposite SERS platform possessed remarkable Raman activity using copper phthalocyanine (CuPc) as a probe molecule. X-ray photoelectron spectroscopy measurement revealed that the chemical bond Ti-O-C was formed at the interface between graphene and TiO 2 in EG-TiO 2 nanocomposites. Both experimental and theoretical results demonstrated that the obvious Raman enhancement was attributed to TiO 2 -induced Fermi level shift of graphene, resulting in effective charge transfer between EG-TiO 2 nanocomposites and molecules. Taking advantage of a marked Raman response of the CuPc molecule on the EG-TiO 2 nanocomposite surface as well as specific recognition of CuPc toward multiple telomeric G-quadruplex, EG-TiO 2 nanocomposites were tactfully employed as the SERS substrate for selective and ultrasensitive determination of telomerase activity, with a low detection limit down to 2.07 × 10 -16 IU. Interestingly, the self-cleaning characteristic of EG-TiO 2 nanocomposites under visible light irradiation successfully provided a recycling ability for this plasmon-free EG-TiO 2 substrate. The present SERS biosensor with high analytical performance, such as high selectivity and sensitivity, has been further explored to determine telomerase activity in stem cells as well as to count the cell numbers. More importantly, using this useful tool, it was discovered that telomerase activity plays an important role in the proliferation and differentiation from human mesenchymal stem cells to neural stem cells. This work has not only established an approach for gaining fundamental insights into the chemical mechanism (CM
International Nuclear Information System (INIS)
Nkoma, J.S.
1982-08-01
A quantum-mechanical theory for the inelastic scattering of slow electrons (ISSE) by surface excitations in a thin film is developed. The scattered wave function inside the thin film is obtained by solving the inhomogeneous Schroedinger equation, and it is found to contain terms which show that the back scattered intensity is smaller than the forward scattered intensity. A scattering cross-section for forward scattering is derived and is found to be dependent on transmission factors, wavevectors and fluctuations of the scattering potential. (author)
Electron scattering from pyrimidine
International Nuclear Information System (INIS)
Colmenares, Rafael; Fuss, Martina C; García, Gustavo; Oller, Juan C; Muñoz, Antonio; Blanco, Francisco; Almeida, Diogo; Limão-Vieira, Paulo
2014-01-01
Electron scattering from pyrimidine (C 4 H 4 N 2 ) was investigated over a wide range of energies. Following different experimental and theoretical approaches, total, elastic and ionization cross sections as well as electron energy loss distributions were obtained.
Gravitational Bhabha scattering
International Nuclear Information System (INIS)
Santos, A F; Khanna, Faqir C
2017-01-01
Gravitoelectromagnetism (GEM) as a theory for gravity has been developed similar to the electromagnetic field theory. A weak field approximation of Einstein theory of relativity is similar to GEM. This theory has been quantized. Traditional Bhabha scattering, electron–positron scattering, is based on quantized electrodynamics theory. Usually the amplitude is written in terms of one photon exchange process. With the development of quantized GEM theory, the scattering amplitude will have an additional component based on an exchange of one graviton at the lowest order of perturbation theory. An analysis will provide the relative importance of the two amplitudes for Bhabha scattering. This will allow an analysis of the relative importance of the two amplitudes as the energy of the exchanged particles increases. (paper)
International Nuclear Information System (INIS)
Tezuka, Hirokazu.
1984-10-01
Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)
International Nuclear Information System (INIS)
1991-07-01
This collection contains 21 papers on the application and development of LIDAR (Light Detection and Ranging) Thomson scattering techniques for the determination of spatially resolved electron temperature and density in magnetic confinement experiments, particularly tokamaks. Refs, figs and tabs
International Nuclear Information System (INIS)
Peterson, G.A.
1989-01-01
We briefly review some of the motivations, early results, and techniques of magnetic elastic and inelastic electron-nucleus scattering. We then discuss recent results, especially those acquired at high momentum transfers. 50 refs., 19 figs
Deep inelastic lepton scattering
International Nuclear Information System (INIS)
Nachtmann, O.
1977-01-01
Deep inelastic electron (muon) nucleon and neutrino nucleon scattering as well as electron positron annihilation into hadrons are reviewed from a theoretical point of view. The emphasis is placed on comparisons of quantum chromodynamics with the data. (orig.) [de
Small angle neutron scattering
International Nuclear Information System (INIS)
Bernardini, G.; Cherubini, G.; Fioravanti, A.; Olivi, A.
1976-09-01
A method for the analysis of the data derived from neutron small angle scattering measurements has been accomplished in the case of homogeneous particles, starting from the basic theory without making any assumption on the form of particle size distribution function. The experimental scattering curves are interpreted with the aid the computer by means of a proper routine. The parameters obtained are compared with the corresponding ones derived from observations at the transmission electron microscope
International Nuclear Information System (INIS)
Aprile-Giboni, E.; Cantale, G.; Hausammann, R.
1983-01-01
Using the PM1 polarized proton beam at SIN and a polarized target, the elastic pp scattering as well as the inelastic channel pp → π + d have been studied between 400 and 600 MeV. For the elastic reaction, a sufficient number of spin dependent parameters has been measured in order to do a direct reconstruction of the scattering matrix between 38 0 /sub cm/ and 90 0 /sub cm/. 10 references, 6 figures
Efficient scattering of electrons below few keV by Time Domain Structures around injection fronts
Vasko, I.; Agapitov, O. V.; Mozer, F.; Artemyev, A.; Krasnoselskikh, V.
2016-12-01
Van Allen Probes observations show an abundance of non-linear large-amplitude electrostatic spikes around injection fronts in the outer radiation belt. These spikes referred to as Time Domain Structures (TDS) include electron holes, double layers and more complicated solitary waves. The electron scattering driven by TDS may not be evaluated via the standard quasi-linear theory, since TDS are in principle non-linear plasma modes. In this paper we analyze the scattering of electrons by three-dimensional TDS (with non-negligible perpendicular electric field) around injection fronts. We derive the analytical formulas describing the local scattering by single TDS and show that the most efficiently scattered electrons are those in the first cyclotron resonance (electrons crossing TDS on a time scale comparable with their gyroperiod). The analytical formulas are verified via the test-particle simulation. We compute the bounce-averaged diffusion coefficients and demonstrate their dependence on the TDS spatial distribution, individual TDS parameters and L shell. We show that TDS are able to provide the pitch-angle scattering of <5 keV electrons at rate 10-2-10-4 s-1 and, thus, can be responsible for driving loss of electrons out of injections fronts on a time scale from few minutes to few hours. TDS can be, thus, responsible for driving diffuse aurora precipitations conjugated to injection fronts. We show that the pitch-angle scattering rates driven by TDS are comparable with those due to chorus waves and exceed those due to electron cyclotron harmonics. For injections fronts with no significant wave activity in the frequency range corresponding to chorus waves, TDS can be even dominant mechanism for losses of below few keV electrons.
Energy evolution of the large-t elastic scattering and its correlation with multiparticle production
International Nuclear Information System (INIS)
Troshin, S. M.
2013-01-01
It is emphasized that the collective dynamics associated with color confinement is dominating over a point-like mechanism related to a scattering of the proton constituents at the currently available values of the momentum transferred in proton elastic scattering at the LHC. Deep-elastic scattering and its role in the dissimilation of the absorptive and reflective asymptotic scattering mechanisms are discussed with emphasis on the experimental signatures associated with the multiparticle production processes.
Energy evolution of the large-t elastic scattering and its correlation with multiparticle production
Energy Technology Data Exchange (ETDEWEB)
Troshin, S. M. [Institute for High Energy Physics, Protvino, Moscow Region, 142281 (Russian Federation)
2013-04-15
It is emphasized that the collective dynamics associated with color confinement is dominating over a point-like mechanism related to a scattering of the proton constituents at the currently available values of the momentum transferred in proton elastic scattering at the LHC. Deep-elastic scattering and its role in the dissimilation of the absorptive and reflective asymptotic scattering mechanisms are discussed with emphasis on the experimental signatures associated with the multiparticle production processes.
Electron scattering by trapped fermionic atoms
International Nuclear Information System (INIS)
Wang Haijun; Jhe, Wonho
2002-01-01
Considering the Fermi gases of alkali-metal atoms that are trapped in a harmonic potential, we study theoretically the elastic and inelastic scattering of the electrons by the trapped Fermi atoms and present the corresponding differential cross sections. We also obtain the stopping power for the cases that the electronic state as well as the center-of-mass state are excited both separately and simultaneously. It is shown that the elastic scattering process is no longer coherent in contrast to the electron scattering by the atomic Bose-Einstein condensate (BEC). For the inelastic scattering process, on the other hand, the differential cross section is found to be proportional to the 2/3 power of the number of the trapped atoms. In particular, the trapped fermionic atoms display the effect of ''Fermi surface,'' that is, only the energy levels near the Fermi energy have dominant contributions to the scattering process. Moreover, it is found that the stopping power scales as the 7/6 power of the atomic number. These results are fundamentally different from those of the electron scattering by the atomic BEC, mainly due to the different statistics obeyed by the trapped atomic systems
Fermion-boson scattering in ladder approximation
International Nuclear Information System (INIS)
Jafarov, R.G.; Hadjiev, S.A.
1992-10-01
A method of calculation of forward scattering amplitude for fermions and scalar bosons with exchanging of scalar particle is suggested. The Bethe-Salpeter ladder equation for the imaginary part of the amplitude is constructed and a solution in Regge asymptotical form is found and the corrections to the amplitude due to the exit from mass shell are calculated. (author). 8 refs
Reproducibility of artificial multiple scattering media
Marakis, Evangelos; van Harten, Wouter; Uppu, Ravitej; Pinkse, Pepijn Willemszoon Harry
2016-01-01
State of the art authentication systems depend on physical unclonable functions (PUF) [1], physical keys that are assumed unclonable due to technological constraints. Random scattering media, dielectric materials with rapid and random refractive index variations, are considered as ideal optical PUFs
High energy hadron-nucleus scattering
International Nuclear Information System (INIS)
Koplik, J.; Mueller, A.H.
1975-01-01
Theoretical expectations for hadron-nucleus scattering at high energy if the basic hadron-hadron interaction is due to Regge poles and cuts arising in multiperipheral or soft field theory models are described. Experiments at Fermilab may provide a critical test of such models
Scaling, scattering, and blackbody radiation in classical physics
International Nuclear Information System (INIS)
Boyer, Timothy H
2017-01-01
Here we discuss blackbody radiation within the context of classical theory. We note that nonrelativistic classical mechanics and relativistic classical electrodynamics have contrasting scaling symmetries which influence the scattering of radiation. Also, nonrelativistic mechanical systems can be accurately combined with relativistic electromagnetic radiation only provided the nonrelativistic mechanical systems are the low-velocity limits of fully relativistic systems. Application of the no-interaction theorem for relativistic systems limits the scattering mechanical systems for thermal radiation to relativistic classical electrodynamic systems, which involve the Coulomb potential. Whereas the naive use of nonrelativistic scatterers or nonrelativistic classical statistical mechanics leads to the Rayleigh–Jeans spectrum, the use of fully relativistic scatterers leads to the Planck spectrum for blackbody radiation within classical physics. (paper)
Energy transfer in scattering by rotating potentials
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
Quantum mechanical scattering theory is studied for time-dependent. Schrödinger ... the energy transferred to a particle by collision with a rotating blade. Keywords. ..... terms of the unitary group for some time-independent generator. This will ...
Nonelastic electron scattering in mercury telluride
Malik, O P
2002-01-01
By exact solution of the Boltzmann equation, the nonequilibrium charge carrier distribution function is obtained. In the temperature range 4.2 - 300 K, main electron scattering mechanisms are considered by taking into account the nonelastic electron interaction with optical vibrations of the crystal lattice.
SPANDY: a Monte Carlo program for gas target scattering geometry
International Nuclear Information System (INIS)
Jarmie, N.; Jett, J.H.; Niethammer, A.C.
1977-02-01
A Monte Carlo computer program is presented that simulates a two-slit gas target scattering geometry. The program is useful in estimating effects due to finite geometry and multiple scattering in the target foil. Details of the program are presented and experience with a specific example is discussed
Chaotic scattering of two identical point vortex pairs revisited
DEFF Research Database (Denmark)
Tophøj, Laust Emil Hjerrild; Aref, Hassan
2008-01-01
A new numerical exploration suggests that the motion of two vortex pairs, with constituent vortices all of the same absolute circulation, displays chaotic scattering regimes. The mechanisms leading to chaotic scattering are different from the “slingshot effect” identified by Price [Phys. Fluids A...
Small angle X-ray scattering from hydrating tricalcium silicate
International Nuclear Information System (INIS)
Vollet, D.
1983-01-01
The small-angle X-ray scattering technique was used to study the structural evolution of hydrated tricalcium silicate at room temperature. The changes in specific area of the associated porosity and the evolution of density fluctuations in the solid hydrated phase were deduced from the scattering data. A correlation of these variations with the hydration mechanism is tried. (Author) [pt
Electron scattering by molecular oxygen
International Nuclear Information System (INIS)
Duddy, P.E.
1999-03-01
Collisions of electrons with molecules is one of the fundamental processes which occur both in atomic and molecular physics and also in chemistry. These collisions are vital in determining the energy balance and transport properties of electrons in gases and plasmas at low temperatures. There are many important applications for the basic understanding of these collision processes. For example, the study of planetary atmospheres and the interstellar medium involves electron collisions with both molecules and molecular ions. In particular, two of the major cooling mechanisms of electrons in the Earth's ionosphere are (i) the fine structure changing transitions of oxygen atoms by electron impact and (ii) the resonant electron-impact vibrational excitation of N 2 . Other applications include magnetohydrodynamic power generation and laser physics. A molecule, by definition, will contain more than one nucleus and consequently the effect of nuclear motion in the molecule leads to many extra processes in electron scattering by molecules which cannot occur in electron-atom scattering. As for atoms, both elastic and inelastic scattering occur, but in the case of inelastic electron scattering by molecules, the target molecule is excited to a different state by the process. The excitation may be one, or some combination, of rotational, vibrational and electronic transitions. Other reactions which may occur include dissociation of the molecule into its constituent atoms or ionisation. Another difficulty arises when considering the interactions between the electron and the molecule, This interaction, which considerably complicates the calculation, is non-spherical and various methods have been developed over the years to represent this interaction. This thesis considers electron scattering by molecular oxygen in the low energy range i.e. 0-15eV. These collisions are of considerable interest in atmospheric physics and chemistry where the electron impact excitation of O 2 has
Lee, Myoung-Jae; Jung, Young-Dae
2017-10-01
The influence of Kohn singularity on the occurrence scattering time for the electron-ion interaction is investigated in degenerate quantum collisional plasmas. The first-order eikonal analysis is used to obtain the scattering amplitude and the occurrence scattering time. The result shows that the Friedel oscillation due to the Kohn singularity suppresses the advance phenomena of occurrence scattering time in both forward and backward scattering domains. It is shown that the increase of plasmon energy would reduce the time advance for both forward and backward scattering domains. However, the increase of Fermi energy would enhance the phenomena of time advance. It is also found that the time advance with high collision frequency is larger than that with low collision frequency for the forward scattering domain and vice versa for the backward scattering domain. We have shown that the time advance is stronger in general for the forward scattering domain than that for the backward scattering domain.
Shape dependent resonance light scattering properties of gold nanorods
International Nuclear Information System (INIS)
Zhu Jian; Huang Liqing; Zhao Junwu; Wang Yongchang; Zhao Yanrui; Hao Limei; Lu Yimin
2005-01-01
Suspended gold nanorods with mean aspect ratio 2.5 have been synthesized via electrochemical method. Resonance scattering properties have been studied. Two scattering peaks fixed at 400 and 640 nm are due to the scattering of the gold nanorods via coupling to the transverse and longitudinal surface plasmon resonance. The quasi-static calculation results indicate that with the increasing aspect ratio of the nanorods, the longer wavelength scattering peak red shifts linearly and the shorter wavelength peak blue shifts non-linearly. When aspect ratio a/b = 1.0, ellipse degenerate to sphere and the two peaks unite into one peak at 450 nm
Interactive directional subsurface scattering and transport of emergent light
DEFF Research Database (Denmark)
Dal Corso, Alessandro; Frisvad, Jeppe Revall; Mosegaard, Jesper
2016-01-01
need to store elements of irradiance from specific directions. To include changes in subsurface scattering due to changes in the direction of the incident light, we instead sample incident radiance and store scattered radiosity. This enables us to accommodate not only the common distance....... To build our maps of scattered radiosity, we progressively render the model from different directions using an importance sampling pattern based on the optical properties of the material. We obtain interactive frame rates, our subsurface scattering results are close to ground truth, and our technique...
Weinberg, Steven
2015-09-01
Preface; Notation; 1. Historical introduction; 2. Particle states in a central potential; 3. General principles of quantum mechanics; 4. Spin; 5. Approximations for energy eigenstates; 6. Approximations for time-dependent problems; 7. Potential scattering; 8. General scattering theory; 9. The canonical formalism; 10. Charged particles in electromagnetic fields; 11. The quantum theory of radiation; 12. Entanglement; Author index; Subject index.
Influence of the angular scattering of electrons on the runaway threshold in air
Chanrion, O.; Bonaventura, Z.; Bourdon, A.; Neubert, T.
2016-04-01
The runaway electron mechanism is of great importance for the understanding of the generation of x- and gamma rays in atmospheric discharges. In 1991, terrestrial gamma-ray flashes (TGFs) were discovered by the Compton Gamma-Ray Observatory. Those emissions are bremsstrahlung from high energy electrons that run away in electric fields associated with thunderstorms. In this paper, we discuss the runaway threshold definition with a particular interest in the influence of the angular scattering for electron energy close to the threshold. In order to understand the mechanism of runaway, we compare the outcome of different Fokker-Planck and Monte Carlo models with increasing complexity in the description of the scattering. The results show that the inclusion of the stochastic nature of collisions smooths the probability to run away around the threshold. Furthermore, we observe that a significant number of electrons diffuse out of the runaway regime when we take into account the diffusion in angle due to the scattering. Those results suggest using a runaway threshold energy based on the Fokker-Planck model assuming the angular equilibrium that is 1.6 to 1.8 times higher than the one proposed by [1, 2], depending on the magnitude of the ambient electric field. The threshold also is found to be 5 to 26 times higher than the one assuming forward scattering. We give a fitted formula for the threshold field valid over a large range of electric fields. Furthermore, we have shown that the assumption of forward scattering is not valid below 1 MeV where the runaway threshold usually is defined. These results are important for the thermal runaway and the runaway electron avalanche discharge mechanisms suggested to participate in the TGF generation.
X-ray scattering in giant magneto-resistive multilayers
International Nuclear Information System (INIS)
Fulthorpe, B.D.
1999-01-01
The scattering mechanisms responsible for Giant Magneto-Resistance (GMR) in magnetic multilayers are believed to be related to many aspects of the multilayer structure. X-ray scattering techniques provide a powerful method with which to study the bulk and interface morphology in these systems, and are therefore crucial in developing an understanding of the dominant factors influencing the magnitude of the GMR. Reflectivity measurements performed on a series of Co/Cu multilayers, sputter deposited onto etched silicon, reveal no variation in the interface roughness with etching voltage, the thickness of the individual layers also remaining constant. The observed decrease in the GMR cannot, therefore, be attributed to variations in spacer thickness or interfacial spin-independent scattering. Electron and X-ray Diffraction measurements suggest the reduction in GMR is due to a loss of antiferromagnetic coupling associated with a transformation of the texture from a randomly oriented to well oriented (111) polycrystalline texture, and subsequent reduction in the volume fraction of (100) oriented grains. Interfaces within Co/Cu are found to propagate with a high degree of conformality with increasing bilayer number, with an out-of-plane correlation length well in excess of 300A. In contrast, the Co/Pt system exhibits a limiting out-of-plane correlation length of the order of 350A arising from a columnar growth mode. X-ray Reflectivity and Diffraction measurements provide' no structural interpretation for the 3-fold enhancement in the rate of increase of the saturation conductivity, as a function of spacer thickness, in Fe/Au (100) compared to Fe/Au (111), or why large oscillations in the GMR occur for the (100) orientation only. Such observations are, however, consistent with the existence of a channelling mechanism in Fe/Au (100). Grazing Incidence Fluorescence data indicates that Nb acts as a surfactant in Fe/Au (111) growth on sapphire. The influence of different
Scattering and absorption of particles emitted by a point source in a cluster of point scatterers
International Nuclear Information System (INIS)
Liljequist, D.
2012-01-01
A theory for the scattering and absorption of particles isotropically emitted by a point source in a cluster of point scatterers is described and related to the theory for the scattering of an incident particle beam. The quantum mechanical probability of escape from the cluster in different directions is calculated, as well as the spatial distribution of absorption events within the cluster. A source strength renormalization procedure is required. The average quantum scattering in clusters with randomly shifting scatterer positions is compared to trajectory simulation with the aim of studying the validity of the trajectory method. Differences between the results of the quantum and trajectory methods are found primarily for wavelengths larger than the average distance between nearest neighbour scatterers. The average quantum results include, for example, a local minimum in the number of absorption events at the location of the point source and interference patterns in the angle-dependent escape probability as well as in the distribution of absorption events. The relative error of the trajectory method is in general, though not generally, of similar magnitude as that obtained for beam scattering.
Diffuse scattering from periodic and aperiodic crystals
International Nuclear Information System (INIS)
Frey, F.
1997-01-01
A (selective) review on diffuse scattering from periodic and aperiodic crystalline solids is given to demonstrate the wide field of applications in basic and applied research. After a general introduction in this field each topic is exemplified by one or two examples. Main emphasis is laid on recent work. More established work, e.g., on diffuse scattering from metals and alloys, polytypes, stacking disorder from layered structures, etc. is omitted due to the availability of excellent textbooks and reviews. Finally a short summary of recent developments of experimental methods and evaluation techniques is presented. (orig.)
Magnetism and magnetic materials probed with neutron scattering
International Nuclear Information System (INIS)
Velthuis, S.G.E. te; Pappas, C.
2014-01-01
Neutron scattering techniques are becoming increasingly accessible to a broader range of scientific communities, in part due to the onset of next-generation, high-power spallation sources, high-performance, sophisticated instruments and data analysis tools. These technical advances also advantageously impact research into magnetism and magnetic materials, where neutrons play a major role. In this Current Perspective series, the achievements and future prospects of elastic and inelastic neutron scattering, polarized neutron reflectometry, small angle neutron scattering, and neutron imaging, are highlighted as they apply to research into magnetic frustration, superconductivity and magnetism at the nanoscale. - Highlights: • Introduction to Current Perspective series titled Magnetism and Magnetic Materials probed with Neutron Scattering. • Elastic and inelastic neutron scattering in systems with magnetic frustration and superconductivity. • Small angle neutron scattering and polarized neutron reflectometry in studying magnetism at the nanoscale. • Imaging of magnetic fields and domains
Magnetism and magnetic materials probed with neutron scattering
Energy Technology Data Exchange (ETDEWEB)
Velthuis, S.G.E. te, E-mail: tevelthuis@anl.gov [Materials Science Division, Argonne National Laboratory, 9700 S Cass Ave, Argonne, IL 60439 (United States); Pappas, C. [Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629JB Delft (Netherlands)
2014-01-15
Neutron scattering techniques are becoming increasingly accessible to a broader range of scientific communities, in part due to the onset of next-generation, high-power spallation sources, high-performance, sophisticated instruments and data analysis tools. These technical advances also advantageously impact research into magnetism and magnetic materials, where neutrons play a major role. In this Current Perspective series, the achievements and future prospects of elastic and inelastic neutron scattering, polarized neutron reflectometry, small angle neutron scattering, and neutron imaging, are highlighted as they apply to research into magnetic frustration, superconductivity and magnetism at the nanoscale. - Highlights: • Introduction to Current Perspective series titled Magnetism and Magnetic Materials probed with Neutron Scattering. • Elastic and inelastic neutron scattering in systems with magnetic frustration and superconductivity. • Small angle neutron scattering and polarized neutron reflectometry in studying magnetism at the nanoscale. • Imaging of magnetic fields and domains.
Realizing total reciprocity violation in the phase for photon scattering.
Deák, László; Bottyán, László; Fülöp, Tamás; Merkel, Dániel Géza; Nagy, Dénes Lajos; Sajti, Szilárd; Schulze, Kai Sven; Spiering, Hartmut; Uschmann, Ingo; Wille, Hans-Christian
2017-02-22
Reciprocity is when wave or quantum scattering satisfies a symmetry property, connecting a scattering process with the reversed one. While reciprocity involves the interchange of source and detector, it is fundamentally different from rotational invariance, and is a generalization of time reversal invariance, occurring in absorptive media as well. Due to its presence at diverse areas of physics, it admits a wide variety of applications. For polarization dependent scatterings, reciprocity is often violated, but violation in the phase of the scattering amplitude is much harder to experimentally observe than violation in magnitude. Enabled by the advantageous properties of nuclear resonance scattering of synchrotron radiation, we have measured maximal, i.e., 180-degree, reciprocity violation in the phase. For accessing phase information, we introduced a new version of stroboscopic detection. The scattering setting was devised based on a generalized reciprocity theorem that opens the way to construct new types of reciprocity related devices.
Relativistic scattering theory of charged spinless particles
International Nuclear Information System (INIS)
Alt, E.O.; Hannemann, M.
1986-01-01
In the context of relativistic quantum mechanics the scattering is discussed of two and three charged spinless particles. The corresponding transition operators are shown to satisfy four-dimensional Lippmann-Schwinger and eight-dimensional Faddeev-type equations, respectively. A simplified model of two particles with Coulomb interaction can be solved exactly. Calculations have been made of (i) the partial wave S-matrix from which the bound state spectrum has been extracted; the latter agrees with a fourth-order result of Schwinger; (ii) the full scattering amplitude which in the weak-field limit coincides with the expression derived by Fried et al. from eikonalized QED. (author)
Virtual neutron scattering experiments
DEFF Research Database (Denmark)
Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael
2016-01-01
We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...
Electron scattering off nuclei
International Nuclear Information System (INIS)
Gattone, A.O.
1989-01-01
Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author) [es
Cold moderator scattering kernels
International Nuclear Information System (INIS)
MacFarlane, R.E.
1989-01-01
New thermal-scattering-law files in ENDF format have been developed for solid methane, liquid methane liquid ortho- and para-hydrogen, and liquid ortho- and para-deuterium using up-to-date models that include such effects as incoherent elastic scattering in the solid, diffusion and hindered vibration and rotations in the liquids, and spin correlations for the hydrogen and deuterium. These files were generated with the new LEAPR module of the NJOY Nuclear Data Processing System. Other modules of this system were used to produce cross sections for these moderators in the correct format for the continuous-energy Monte Carlo code (MCNP) being used for cold-moderator-design calculations at the Los Alamos Neutron Scattering Center (LANSCE). 20 refs., 14 figs
Quantum Optical Multiple Scattering
DEFF Research Database (Denmark)
Ott, Johan Raunkjær
. In the first part we use a scattering-matrix formalism combined with results from random-matrix theory to investigate the interference of quantum optical states on a multiple scattering medium. We investigate a single realization of a scattering medium thereby showing that it is possible to create entangled...... states by interference of squeezed beams. Mixing photon states on the single realization also shows that quantum interference naturally arises by interfering quantum states. We further investigate the ensemble averaged transmission properties of the quantized light and see that the induced quantum...... interference survives even after disorder averaging. The quantum interference manifests itself through increased photon correlations. Furthermore, the theoretical description of a measurement procedure is presented. In this work we relate the noise power spectrum of the total transmitted or reflected light...
Energy Technology Data Exchange (ETDEWEB)
ZALIZNYAK,I.A.; LEE,S.H.
2004-07-30
Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern
Gomez, Humberto
2016-06-01
The CHY representation of scattering amplitudes is based on integrals over the moduli space of a punctured sphere. We replace the punctured sphere by a double-cover version. The resulting scattering equations depend on a parameter Λ controlling the opening of a branch cut. The new representation of scattering amplitudes possesses an enhanced redundancy which can be used to fix, modulo branches, the location of four punctures while promoting Λ to a variable. Via residue theorems we show how CHY formulas break up into sums of products of smaller (off-shell) ones times a propagator. This leads to a powerful way of evaluating CHY integrals of generic rational functions, which we call the Λ algorithm.
Electromagnetic scattering theory
Bird, J. F.; Farrell, R. A.
1986-01-01
Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.
Scattered P'P' waves observed at short distances
Earle, Paul S.; Rost, Sebastian; Shearer, Peter M.; Thomas, Christine
2011-01-01
We detect previously unreported 1 Hz scattered waves at epicentral distances between 30° and 50° and at times between 2300 and 2450 s after the earthquake origin. These waves likely result from off-azimuth scattering of PKPbc to PKPbc in the upper mantle and crust and provide a new tool for mapping variations in fine-scale (10 km) mantle heterogeneity. Array beams from the Large Aperture Seismic Array (LASA) clearly image the scattered energy gradually emerging from the noise and reaching its peak amplitude about 80 s later, and returning to the noise level after 150 s. Stacks of transverse versus radial slowness (ρt, ρr) show two peaks at about (2, -2) and (-2,-2) s/°, indicating the waves arrive along the major arc path (180° to 360°) and significantly off azimuth. We propose a mantle and surface PKPbc to PKPbc scattering mechanism for these observations because (1) it agrees with the initiation time and distinctive slowness signature of the scattered waves and (2) it follows a scattering path analogous to previously observed deep-mantle PK•KP scattering (Chang and Cleary, 1981). The observed upper-mantle scattered waves and PK•KP waves fit into a broader set of scattered waves that we call P′•d•P′, which can scatter from any depth, d, in the mantle.
Decoupling single nanowire mobilities limited by surface scattering and bulk impurity scattering
International Nuclear Information System (INIS)
Khanal, D. R.; Levander, A. X.; Wu, J.; Yu, K. M.; Liliental-Weber, Z.; Walukiewicz, W.; Grandal, J.; Sanchez-Garcia, M. A.; Calleja, E.
2011-01-01
We demonstrate the isolation of two free carrier scattering mechanisms as a function of radial band bending in InN nanowires via universal mobility analysis, where effective carrier mobility is measured as a function of effective electric field in a nanowire field-effect transistor. Our results show that Coulomb scattering limits effective mobility at most effective fields, while surface roughness scattering only limits mobility under very high internal electric fields. High-energy α particle irradiation is used to vary the ionized donor concentration, and the observed decrease in mobility and increase in donor concentration are compared to Hall effect results of high-quality InN thin films. Our results show that for nanowires with relatively high doping and large diameters, controlling Coulomb scattering from ionized dopants should be given precedence over surface engineering when seeking to maximize nanowire mobility.
A bond-order theory on the phonon scattering by vacancies in two-dimensional materials.
Xie, Guofeng; Shen, Yulu; Wei, Xiaolin; Yang, Liwen; Xiao, Huaping; Zhong, Jianxin; Zhang, Gang
2014-05-28
We theoretically investigate the phonon scattering by vacancies, including the impacts of missing mass and linkages (τ(V)(-1)) and the variation of the force constant of bonds associated with vacancies (τ(A)(-1)) by the bond-order-length-strength correlation mechanism. We find that in bulk crystals, the phonon scattering rate due to change of force constant τ(A)(-1) is about three orders of magnitude lower than that due to missing mass and linkages τ(V)(-1). In contrast to the negligible τ(A)(-1) in bulk materials, τ(A)(-1) in two-dimensional materials can be 3-10 folds larger than τ(V)(-1). Incorporating this phonon scattering mechanism to the Boltzmann transport equation derives that the thermal conductivity of vacancy defective graphene is severely reduced even for very low vacancy density. High-frequency phonon contribution to thermal conductivity reduces substantially. Our findings are helpful not only to understand the severe suppression of thermal conductivity by vacancies, but also to manipulate thermal conductivity in two-dimensional materials by phononic engineering.
Neutron scattering. Experiment manuals
Energy Technology Data Exchange (ETDEWEB)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)
2010-07-01
The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)
Diffraction in nuclear scattering
International Nuclear Information System (INIS)
Wojciechowski, H.
1986-01-01
The elastic scattering amplitudes for charged and neutral particles have been decomposed into diffractive and refractive parts by splitting the nuclear elastic scattering matrix elements into components responsible for these effects. It has been shown that the pure geometrical diffractive effect which carries no information about the nuclear interaction is always predominant at forward angle of elastic angular distributions. This fact suggests that for strongly absorbed particles only elastic cross section at backward angles, i.e. the refractive cross section, can give us basic information about the central nuclear potential. 12 refs., 4 figs., 1 tab. (author)
Proton nuclear scattering radiography
International Nuclear Information System (INIS)
Saudinos, J.
1982-04-01
Nuclear scattering of protons allows to radiograph objects with specific properties: 3-dimensional radiography, different information as compared to X-ray technique, hydrogen radiography. Furthermore the nuclear scattering radiography (NSR) is a well adapted method to gating techniques allowing the radiography of fast periodic moving objects. Results obtained on phantoms, formalin fixed head and moving object are shown and discussed. The dose delivery is compatible with clinical use, but at the moment, the irradiation time is too long between 1 and 4 hours. Perspectives to make the radiograph faster and to get a practical method are discussed
Slow neutron scattering experiments
International Nuclear Information System (INIS)
Moon, R.M.
1985-01-01
Neutron scattering is a versatile technique that has been successfully applied to condensed-matter physics, biology, polymer science, chemistry, and materials science. The United States lost its leadership role in this field to Western Europe about 10 years ago. Recently, a modest investment in the United States in new facilities and a positive attitude on the part of the national laboratories toward outside users have resulted in a dramatic increase in the number of US scientists involved in neutron scattering research. Plans are being made for investments in new and improved facilities that could return the leadership role to the United States. 23 references, 4 figures, 3 tables
Neutron scattering. Experiment manuals
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2014-01-01
The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot-single-crystal diffractometer HEiDi, the three-axis spectrometer PANDA, the backscattering spectrometer SPHERES, the DNS neutron-polarization analysis, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering at KWS-1 and KWS-2, a very-small-angle neutron scattering diffractometer with focusing mirror, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)
International Nuclear Information System (INIS)
McCarthy, I.E.
1991-07-01
The coupled-channels-optical method has been implemented using two different approximations to the optical potential. The half-on-shell optical potential involves drastic approximations for numerical feasibility but still gives a good semiquantitative description of the effect of uncoupled channels on electron scattering from hydrogen, helium and sodium. The distorted-wave optical potential makes no approximations other than the weak coupling approximation for uncoupled channels. In applications to hydrogen and sodium it shows promise of describing scattering phenomena excellently at all energies. 27 refs., 5 figs
Neutron scattering. Experiment manuals
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2010-01-01
The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)
Mechanism of a strong rise of Tc due to the calcium doping in Y1-xCaxBa2Cu2.8Zn0.2Oy
International Nuclear Information System (INIS)
Martynova, O.A.; Potapov, D.V.; Gasumyants, V.E.; Vladimirskaya, E.V.
2011-01-01
Highlights: → Calcium is observed to restore superconductivity in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y . → Parameters of the band spectrum and charge-carrier system are determined. → The calcium doping is shown to give a noticeable contribution to the DOS function. → The mechanism of calcium effect on T c in doped YBa 2 Cu 3 O y is discussed. - Abstract: The normal-state transport properties and the critical temperature, T c , for three series of Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y (x = 0-0.2) samples with different oxygen content have been investigated and discussed in comparison with results for other calcium-doped YBa 2 Cu 3 O y . We have observed the calcium doping to restore the superconductivity in the YBa 2 Cu 3 O y system even in case of the preliminary T c suppression by the direct destruction of the CuO 2 planes due to a preliminary doping by zinc. The T c value rises strongly with increasing calcium content and this rise becomes faster for the oxygen-reduced series. Based on a narrow-band model, the parameters of the band spectrum structure and the charge-carrier system in the normal state were determined from the analysis of the thermopower temperature dependences in order to reveal the mechanism of the T c rise under the Ca influence. It is shown that the T c increase in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y is related to the direct Ca ions effect. The mechanism of the calcium influence on the T c value is discussed with respect to the Ca-induced conduction band modification. The calcium doping in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y is shown to give a noticeable contribution to the density-of-states function leading to a strong rise in its value at the Fermi level that results in a restoration of the superconducting properties.
Matter scattering in quadratic gravity and unitarity
Abe, Yugo; Inami, Takeo; Izumi, Keisuke; Kitamura, Tomotaka
2018-03-01
We investigate the ultraviolet (UV) behavior of two-scalar elastic scattering with graviton exchanges in higher-curvature gravity theory. In Einstein gravity, matter scattering is shown not to satisfy the unitarity bound at tree level at high energy. Among some of the possible directions for the UV completion of Einstein gravity, such as string theory, modified gravity, and inclusion of high-mass/high-spin states, we take R_{μν}^2 gravity coupled to matter. We show that matter scattering with graviton interactions satisfies the unitarity bound at high energy, even with negative norm states due to the higher-order derivatives of metric components. The difference in the unitarity property of these two gravity theories is probably connected to that in another UV property, namely, the renormalizability property of the two.
Neutron scattering in Indonesia. Country report
Energy Technology Data Exchange (ETDEWEB)
Ikram, Abarrul [Neutron Scattering Laboratory, R and D Center for Materials Science and Technology, National Nuclear Energy Agency, Serpong (Indonesia)
2000-10-01
Neutron scattering in Indonesia is still alienated due to some reasons and conditions which are discussed. The reactor and its latest operation mode are also described. The neutron beam facilities which include one diffractometer for residual stress measurement, one diffractometer for single crystal structural determination and texture measurement, one high resolution powder diffractometer, one neutron radiography facility, one triple axis spectrometer, one small angle neutron scattering spectrometer and one high resolution small angle neutron scattering spectrometer were presented briefly together with improvements of neutron intensities at some spectrometers in connection with the setting of main beam shutter position. Special attention is given for four instruments mostly related to this workshop. Their performances and problems faced in the past 9 months are presented as well as the future plan for refurbishment and development. (author)
High energy scattering in gravity and supergravity
DEFF Research Database (Denmark)
B. Giddings, Steven; Schmidt-Sommerfeld, Maximilian; Andersen, Jeppe Rosenkrantz
2010-01-01
We investigate features of perturbative gravity and supergravity by studying scattering in the ultraplanckian limit, and sharpen arguments that the dynamics is governed by long-distance physics. A simple example capturing aspects of the eikonal resummation suggests why short distance phenomena...... and in particular divergences or nonrenormalizability do not necessarily play a central role in this regime. A more profound problem is apparently unitarity. These considerations can be illustrated by showing that known gravity and supergravity amplitudes have the same long-distance behavior, despite the extra...... a physical scattering process, and ultraplanckian scattering exhibiting Regge behavior. These arguments sharpen the need to find a nonperturbative completion of gravity with mechanisms which restore unitarity in the strong gravity regime....
Exclusive compton scattering on the proton
International Nuclear Information System (INIS)
Chen, J.P.; Chudakov, E.; DeJager, C.; Degtyarenko, P.; Ent, R.; Gomez, J.; Hansen, O.; Keppel, C.; Klein, F.; Kuss, M.
1999-01-01
An experiment is proposed to measure the cross sections for Real Compton Scattering from the proton in the energy range 3-6 GeV and over a wide angular range, and to measure the longitudinal and transverse components of the polarization transfer to the recoil proton at a single kinematic point. Together, these measurements will test models of the reaction mechanism and determine new structure functions of the proton that are related to the same non-forward parton densities that determine the elastic electron scattering form factors and the parton densities. The experiment utilizes an untagged Bremsstrahlung photon beam and the standard Hall A cryogenic targets. The scattered photon is detected in a photon spectrometer, currently under construction. The coincident recoil proton is detected in one of the Hall A magnetic spectrometers and its polarization components are measured in the existing Focal Plane Polarimeter. This proposal extends and supersedes E97 - 108 which was approved by PAC13. (author)
Exclusive compton scattering on the proton
Energy Technology Data Exchange (ETDEWEB)
Chen, J.P.; Chudakov, E.; DeJager, C.; Degtyarenko, P.; Ent, R.; Gomez, J.; Hansen, O.; Keppel, C.; Klein, F.; Kuss, M. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)] [and others
1999-07-01
An experiment is proposed to measure the cross sections for Real Compton Scattering from the proton in the energy range 3-6 GeV and over a wide angular range, and to measure the longitudinal and transverse components of the polarization transfer to the recoil proton at a single kinematic point. Together, these measurements will test models of the reaction mechanism and determine new structure functions of the proton that are related to the same non-forward parton densities that determine the elastic electron scattering form factors and the parton densities. The experiment utilizes an untagged Bremsstrahlung photon beam and the standard Hall A cryogenic targets. The scattered photon is detected in a photon spectrometer, currently under construction. The coincident recoil proton is detected in one of the Hall A magnetic spectrometers and its polarization components are measured in the existing Focal Plane Polarimeter. This proposal extends and supersedes E97 - 108 which was approved by PAC13. (author)
Exclusive Compton Scattering on the Proton
International Nuclear Information System (INIS)
Chen, J. P.; Chudakov, E.; DeJager, C.; Degtyarenko, P.; Ent, R.; Gomez, J.; Hansen, O.; Keppel, C.; Klein, F.; Kuss, M.; LeRose, J.; Liang, M.; Michaels, R.; Mitchell, J.; Liyanage, N.; Rutt, P.; Saha, A.; Wojtsekhowski, B.; Bouwhuis, M.; Chang, T.H.; Holt, R. J.; Nathan, A. M.; Roedelbronn, M.; Wijesooriya, K.; Williamson, S. E.; Dodge, G.; Hyde-Wright, C.; Radyushkin, A.; Sabatie, F.; Weinstein, L. B.; Ulmer, P.; Bosted, P.; Finn, J. M.; Jones, M.; Churchwell, S.; Howell, C.; Gilman, R.; Glashausser, C.; Jiang, X.; Ransome, R.; Strauch, S.; Berthot, J.; Bertin, P.; Fonvielle, H.; Roblin, Y.; Bertozzi, W.; Gilad, S.; Rowntree, D.; Zu, Z.; Brown, D.; Chang, G.; Afanasev, A.; Egiyan, K.; Hoohauneysan, E.; Ketikyan, A.; Mailyan, S.; Petrosyan, A.; Shahinyan, A.; Voskanyan, H.; Boeglin, W.; Markowitz, P.; Hines, J.; Strobel, G.; Templon, J.; Feldman, G.; Morris, C. L.; Gladyshev, V.; Lindgren, R. A.; Calarco, J.; Hersman, W.; Leuschner, M.; Gasparian, A.
1999-01-01
An experiment is proposed to measure the cross sections for Real Compton Scattering from the proton in the energy range 3-6 GeV and over a wide angular range; and to measure the longitudinal and transverse components of the polarization transfer to the recoil proton at a single kinematic point. Together; these measurements will test models of the reaction mechanism and determine new structure functions of the proton that are related to the same nonforward parton densities that determine the elastic electron scattering form factors and the parton densities. The experiment utilizes an untagged bremsstrahlung photon beam and the standard Hall A cryogenic targets. The scattered photon is detected in a photon spectrometer; currently under construction. The coincident recoil proton is detected in one of the Hall A magnetic spectrometers and its polarization components are measured in the existing Focal Plane Polarimeter. This proposal extends and supercedes E97-108 which was approved by PAC13
Directory of Open Access Journals (Sweden)
Subramanian Vaidyanathan
2013-01-01
Full Text Available A 22-year-old male sustained C-6 tetraplegia in 1992. In 1993, intravenous pyelography revealed normal kidneys. Suprapubic cystostomy was performed. He underwent open cystolithotomy in 2004 and 2008. In 2009, computed tomography revealed bilateral renal calculi. Coagulum pyelolithotomy of left kidney was performed. Pleura and peritoneum were opened. Peritoneum could not be closed. Following surgery, he developed pulmonary atelectasis; he required tracheostomy and mechanical ventilation. He did not tolerate nasogastric feeding. CT of abdomen revealed bilateral renal calculi and features of proximal small bowel obstruction. Laparotomy revealed small bowel obstruction due to dense inflammatory adhesions involving multiple small bowel loops which protruded through the defect in sigmoid mesocolon and fixed posteriorly over the area of previous intervention. All adhesions were divided. The wide defect in mesocolon was not closed. In 2010, this patient again developed vomiting and distension of abdomen. Laparotomy revealed multiple adhesions. He developed chest infection and required ventilatory support again. He developed pressure sores and depression. Later abdominal symptoms recurred. This patient’s general condition deteriorated and he expired in 2011. Conclusion. Risk of postoperative complications could have been reduced if minimally invasive surgery had been performed instead of open surgery to remove stones from left kidney. Suprapubic cystostomy predisposed to repeated occurrence of stones in urinary bladder and kidneys. Spinal cord physicians should try to establish intermittent catheterisation regime in tetraplegic patients.
Neutron scattering from quantum liquids
International Nuclear Information System (INIS)
Cowley, R.A.
1976-01-01
Recent neutron scattering measurements on the quantum liquids 4 He and 3 He are described. In the Bose superfluid there is a well-defined excitation for wave vectors less than 3.6 A -1 . In the Fermi liquid measurements are much more difficult because of the large absorption cross section, but measurements at the Institute Laue-Langevin have shown that there are no well-defined excitations at 0.63 0 K for wave vectors between 1.0 and 2.6 A -1 . The difference between these results is due to the existence of particle-hole excitations in the Fermi liquid into which collective excitations can decay. Because of the simplicity of the excitations in 4 He, it has become a testing ground for the effects of the interactions between the excitations. Measurements are described which show that while roton-roton interactions are attractive at small wave vectors they are repulsive at larger wave vectors. The scattering at large momentum transfer in 4 He has been measured, but its interpretation is still open to question
International Nuclear Information System (INIS)
Johnson, R.C.
1980-01-01
High energy and small momentum transfer 2 'yields' 2 hadronic scattering processes are described in the physical framework of particle exchange. Particle production in high energy collisions is considered with emphasis on the features of inclusive reactions though with some remarks on exclusive processes. (U.K.)
Critical scattering by bubbles
International Nuclear Information System (INIS)
Fiedler-Ferrari, N.; Nussenzveig, H.M.
1986-11-01
We apply the complex angular momentum theory to the problem of the critical scattering of light by spherical cavities in the high frequency limit (permittivity greater than the external media) (e.g, air bubble in water) (M.W.O.) [pt
Radiation scattering techniques
International Nuclear Information System (INIS)
Edmonds, E.A.
1986-01-01
Radiation backscattering techniques are useful when access to an item to be inspected is restricted to one side. These techniques are very sensitive to geometrical effects. Scattering processes and their application to the determination of voids, thickness measuring, well-logging and the use of x-ray fluorescence techniques are discussed. (U.K.)
International Nuclear Information System (INIS)
Windmolders, R.
1989-01-01
In this paper the following topics are reviewed: 1. the structure functions measured in deep inelastic e-N, μ-N and ν-N scattering; 2. nuclear effects on the structure functions; 3. nuclear effects on the fragmentation functions; 4. the spin dependent structure functions and their interpretation in terms of nucleon constituents. (orig./HSI)
Deeply Virtual Neutrino Scattering
International Nuclear Information System (INIS)
Ales Psaker
2007-01-01
We investigate the extension of the deeply virtual Compton scattering process into the weak interaction sector. Standard electromagnetic Compton scattering provides a unique tool for studying hadrons, which is one of the most fascinating frontiers of modern science. In this process the relevant Compton scattering amplitude probes the hadron structure by means of two quark electromagnetic currents. We argue that replacing one of the currents with the weak interaction current can promise a new insight. The paper is organized as follows. In Sec. II we briefly discuss the features of the handbag factorization scheme. We introduce a new set of phenomenological functions, known as generalized parton distributions (GPDs) [1-6], and discuss some of their basic properties in Sec. III. An application of the GPD formalism to the neutrino-induced deeply virtual Compton scattering in the kinematics relevant to future high-intensity neutrino experiments is given in Sec. IV. The cross section results are presented in Sec. V. Finally, in Sec. VI we draw some conclusions and discuss future prospects. Some of the formal results in this paper have appeared in preliminary reports in Refs. [7] and [8], whereas a comprehensive analysis of the weak neutral and weak charged current DVCS reactions in collaboration with W. Melnitchouk and A. Radyushkin has been presented in Ref. [9
Symposium on neutron scattering
International Nuclear Information System (INIS)
Lehmann, M.S.; Saenger, W.; Hildebrandt, G.; Dachs, H.
1984-01-01
Extended abstracts of the named symposium are presented. The first part of this report contains the abstracts of the lectures, the second those of the posters. Topics discussed on the symposium include neutron diffraction and neutron scattering studies in magnetism, solid state chemistry and physics, materials research. Some papers discussing instruments and methods are included too. (GSCH)
International Nuclear Information System (INIS)
Santoso, B.
1976-01-01
Green Lippmann-Schwinger functions operator representations, derivation of perturbation method using Green function and atom electron scattering, are discussed. It is concluded that by using complex coordinate places where resonances occur, can be accurately identified. The resonance can be processed further for practical purposes, for example for the separation of atom. (RUW)
Electron Scattering on deuterium
International Nuclear Information System (INIS)
Platchkov, S.
1987-01-01
Selected electron scattering experiments on the deuteron system are discussed. The main advantages of the electromagnetic probe are recalled. The deuteron A(q 2 ) structure function is analyzed and found to be very sensitive to the neutron electric form factor. Electrodisintegration of the deuteron near threshold is presented as evidence for the importance of meson exchange currents in nuclei [fr
Parity violating electron scattering
International Nuclear Information System (INIS)
McKeown, R.D.
1990-01-01
Previous measurements of parity violation in electron scattering are reviewed with particular emphasis on experimental techniques. Significant progress in the attainment of higher precision is evident in these efforts. These pioneering experiments provide a basis for consideration of a future program of such measurements. In this paper some future plans and possibilities in this field are discussed
Multienergy anomalous diffuse scattering
Czech Academy of Sciences Publication Activity Database
Kopecký, Miloš; Fábry, Jan; Kub, Jiří; Lausi, A.; Busetto, E.
2008-01-01
Roč. 100, č. 19 (2008), 195504/1-195504/4 ISSN 0031-9007 R&D Projects: GA AV ČR IAA100100529 Institutional research plan: CEZ:AV0Z10100523 Keywords : diffuse scattering * x-rays * structure determination Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.180, year: 2008
Directory of Open Access Journals (Sweden)
Robert de Mello Koch
2017-05-01
Full Text Available We study the worldsheet S-matrix of a string attached to a D-brane in AdS5×S5. The D-brane is either a giant graviton or a dual giant graviton. In the gauge theory, the operators we consider belong to the su(2|3 sector of the theory. Magnon excitations of open strings can exhibit both elastic (when magnons in the bulk of the string scatter and inelastic (when magnons at the endpoint of an open string participate scattering. Both of these S-matrices are determined (up to an overall phase by the su(2|22 global symmetry of the theory. In this note we study the S-matrix for inelastic scattering. We show that it exhibits poles corresponding to boundstates of bulk and boundary magnons. A crossing equation is derived for the overall phase. It reproduces the crossing equation for maximal giant gravitons, in the appropriate limit. Finally, scattering in the su(2 sector is computed to two loops. This two loop result, which determines the overall phase to two loops, will be useful when a unique solution to the crossing equation is to be selected.
Swiftly moving focus points and forming shapes through the scattering media
Tran, Vinh; Sahoo, Sujit Kumar; Tang, Dongliang; Dang, Cuong
2018-02-01
Propagation of light through scattering media such as ground glass or biological tissue limits the quality and intensity of focusing point. Wave front shaping technique which uses spatial light modulator (SLM) devices to reshape the field profile of incoming light, is considered as one of the most effective and convenient methods. Advanced biomedical or manufacturing applications require drawing various contours or shapes quickly and precisely. However, creating each shape behind the scattering medium needs different phase profiles, which are time consuming to optimize or measure. Here, we demonstrate a technique to draw various shapes or contours behind the scattering medium by swiftly moving the focus point without any mechanical movements. Our technique relies on the existence of speckle correlation property in scattering media, also known as optical memory effect. In our procedure, we first modulate the phase-only SLM to create the focus point on the other side of scattering medium. Then, we digitally shift the preoptimized phase profile on the SLM and ramp it to tilt the beam accordingly. Now, the incoming beam with identical phase profile shines on the same scattering region at a tilted angle to regenerate the focus point at the desired position due to memory effect. Moreover, with linear combination of different field patterns, we can generate a single phase profile on SLM to produce two, three or more focus points simultaneously on the other side of a turbid medium. Our method could provide a useful tool for prominent applications such as opto-genetic excitation, minimally invasive laser surgery and other related fields.
Atmospheric scattering corrections to solar radiometry
International Nuclear Information System (INIS)
Box, M.A.; Deepak, A.
1979-01-01
Whenever a solar radiometer is used to measure direct solar radiation, some diffuse sky radiation invariably enters the detector's field of view along with the direct beam. Therefore, the atmospheric optical depth obtained by the use of Bouguer's transmission law (also called Beer-Lambert's law), that is valid only for direct radiation, needs to be corrected by taking account of the scattered radiation. In this paper we shall discuss the correction factors needed to account for the diffuse (i.e., singly and multiply scattered) radiation and the algorithms developed for retrieving aerosol size distribution from such measurements. For a radiometer with a small field of view (half-cone angle 0 ) and relatively clear skies (optical depths <0.4), it is shown that the total diffuse contributions represents approximately l% of the total intensity. It is assumed here that the main contributions to the diffuse radiation within the detector's view cone are due to single scattering by molecules and aerosols and multiple scattering by molecules alone, aerosol multiple scattering contributions being treated as negligibly small. The theory and the numerical results discussed in this paper will be helpful not only in making corrections to the measured optical depth data but also in designing improved solar radiometers
Progress report on neutron scattering at JAERI
Energy Technology Data Exchange (ETDEWEB)
Morii, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1998-10-01
In the first half of fiscal year 1997, JRR-3M was operated for 97 days followed by a long term shut down for its annual maintenance. Three days were lost out of 100 scheduled operation days, due to a trouble in irradiation facility. Neutron scattering research activities at the JRR-3M have been extended from that of fiscal year 1996. In the Research Group for Quantum Condensed Matter System, experimental study under high pressures, low temperatures and high fields as well as coupling of these conditions were planned to find new quantum condensed matter systems. And, obtained experimental results were immediately provided to theorists for their investigations. In cooperation with new group, Research Group for Neutron Scattering of Strongly Correlated Electron Systems and Research Group for Neutron Scattering at Ultralow Temperatures were carrying neutron scattering experiments at JRR-3M. Research Group for Neutron Crystallography in Biology had opened a way for investigating biomatter neutron diffraction research with high experimental accuracy by growing a millimeter-class large single crystal. In fiscal year 1997, 39 research projects were conducted by these four groups and other staffs in JAERI, 27 projects collaborated with university researchers and 3 projects collaborated with private enterprises were also conducted as complementary researches. 2117 days of machine times were requested to use 8 neutron scattering instruments this year, which corresponded to 1.51 times larger than those planned at its beginning. (G.K.)
Phase object retrieval through scattering medium
Zhao, Ming; Zhao, Meijing; Wu, Houde; Xu, Wenhai
2018-05-01
Optical imaging through a scattering medium has been an interesting and important research topic, especially in the field of biomedical imaging. However, it is still a challenging task due to strong scattering. This paper proposes to recover the phase object behind the scattering medium from one single-shot speckle intensity image using calibrated transmission matrices (TMs). We construct the forward model as a non-linear mapping, since the intensity image loses the phase information, and then a generalized phase retrieval algorithm is employed to recover the hidden object. Moreover, we show that a phase object can be reconstructed with a small portion of the speckle image captured by the camera. The simulation is performed to demonstrate our scheme and test its performance. Finally, a real experiment is set up, we measure the TMs from the scattering medium, and then use it to reconstruct the hidden object. We show that a phase object of size 32 × 32 is retrieved from 150 × 150 speckle grains, which is only 1/50 of the speckles area. We believe our proposed method can benefit the community of imaging through the scattering medium.
KN scattering in the nonrelativistic quark model
International Nuclear Information System (INIS)
Barnes, F.E.
1995-01-01
KN scattering is of interest as a probe of nuclear structure and, more fundamentally, as a laboratory for the study of nonresonant hadron-hadron interactions. KN is a I theoretically attractive channel because of its simplicity, having only S = 1/2, no one pion exchange contributions and no valence q anti q annihilation. It may therefore be useful for the study of short-ranged quark forces analogous to the NN repulsive core. Since there are two isospin states, comparison of two closely related amplitudes is possible. This contribution reviews the experimental status of S-wave KN scattering and related theoretical studies based on quark-gluon dynamics. The experimental low-energy S-wave phase shift is well established for I = 1, but is not yet well determined for I = 0. The ratio of I = 0 to I = 1 scattering lengths is an interesting number theoretically, and may discriminate between different scattering mechanisms. A measurement of these scattering lengths at DAPHNE would be a useful contribution to low energy hadron physics
Electron scattering on metal clusters and fullerenes
International Nuclear Information System (INIS)
Solov'yov, A.V.
2001-01-01
This paper gives a survey of physical phenomena manifesting themselves in electron scattering on atomic clusters. The main emphasis is made on electron scattering on fullerenes and metal clusters, however some results are applicable to other types of clusters as well. This work is addressed to theoretical aspects of electron-cluster scattering, however some experimental results are also discussed. It is demonstrated that the electron diffraction plays important role in the formation of both elastic and inelastic electron scattering cross sections. It is elucidated the essential role of the multipole surface and volume plasmon excitations in the formation of electron energy loss spectra on clusters (differential and total, above and below ionization potential) as well as the total inelastic scattering cross sections. Particular attention is paid to the elucidation of the role of the polarization interaction in low energy electron-cluster collisions. This problem is considered for electron attachment to metallic clusters and the plasmon enhanced photon emission. Finally, mechanisms of electron excitation widths formation and relaxation of electron excitations in metal clusters and fullerenes are discussed. (authors)
Small angle neutron scattering
Directory of Open Access Journals (Sweden)
Cousin Fabrice
2015-01-01
Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of
Light scattering reviews 8 radiative transfer and light scattering
Kokhanovsky, Alexander A
2013-01-01
Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.
Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds
Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola
2014-11-01
Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.
Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds.
Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola
2014-11-01
Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp(3) vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.
Phonon scattering in quasi-one-dimensional structure
Energy Technology Data Exchange (ETDEWEB)
Bourahla, B., E-mail: bourahla_boualem@yahoo.f [Laboratoire de Physique et Chimie Quantique, Universite de Tizi Ouzou, BP 17 RP 15000 (Algeria); Laboratoire de Physique de l' etat Condense, UMR 6087, Universite du Maine, 72085 Le Mans (France); Nafa, O. [Laboratoire de Physique et Chimie Quantique, Universite de Tizi Ouzou, BP 17 RP 15000 (Algeria); Tigrine, R. [Laboratoire de Physique et Chimie Quantique, Universite de Tizi Ouzou, BP 17 RP 15000 (Algeria); Laboratoire de Physique de l' etat Condense, UMR 6087, Universite du Maine, 72085 Le Mans (France)
2011-02-15
We introduce a model to study a symmetric nanocontact, whereby its mechanical properties can be analyzed via the vibration spectra. The model system consists of two groups of triple semi-infinite atomic chains joined by atoms in between. The matching method theoretical approach is used to calculate the coherent reflection and transmission scattering probabilities, the characteristic vibration Green functions and densities of states (DOS), for the vibration components of the individual atomic sites that constitute a complete representation of the nanocontact domain boundaries. The nanocontact observables are numerically calculated for different cases of elastic hardening and softening, to investigate how the local dynamics can respond to changes in the microscopic environment on the nanocontact domain. The analysis of the vibration spectra and the DOS demonstrate the fluctuations, related to Fano resonances, due to the coherent coupling between traveling phonons and the localized vibration modes in the nanocontact domain.