Energy Technology Data Exchange (ETDEWEB)

The formation of a quasiequilibrium beam distribution matched to an alternating-gradient quadrupole focusing lattice by means of the adiabatic turn-on of the oscillating focusing field is studied numerically using particle-in-cell simulations. Quiescent beam propagation over several hundred lattice periods is demonstrated for a broad range of beam intensities and vacuum phase advances describing the strength of the oscillating focusing field. Properties of the matched-beam distribution are investigated. In particular, self-similar evolution of the beam density profile is observed over a wide range of system parameters. The numerical simulations are performed using the WARP particle-in-cell code.

International Nuclear Information System (INIS)

The impulse method has been used to study "9"3Nb (nuclear quadrupole resonance (NQR) parameters quadrupole connection constant, spin-lattice and spin-spin relaxation times) in binary intermetallic compounds of Nb_3X (x=Al, Ga, Ge, Sn, Pt, Os, Ir, Sb) and in some ternary phases on the basis of the Nb_3Al compound. The discussion on experimental data obtained is carried out in approximation of a tight connection for d-electrons.

Energy Technology Data Exchange (ETDEWEB)

The longitudinal and transverse dynamics of a heavy ion fusion beam during the drift compression and final focus phase is studied. A lattice design with four time-dependent magnets is described that focuses the entire beam pulse onto a single focal point with the same spot size.

Energy Technology Data Exchange (ETDEWEB)

We survey results in lattice quantum chromodynamics from groups in the USQCD Collaboration. The main focus is on physics, but many aspects of the discussion are aimed at an audience of computational physicists.

CERN Document Server

Conceptual Design of Superconducting Quadrupole Arrays for the Heavy-Ion Fusion

Science.gov (United States)

The electromagnetic properties of the baryon decuplet are calculated in quenched QCD on a 20{sup 3}x40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover fermion action with quark masses providing a pion mass as low as 300 MeV. Magnetic moments and charge radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. We present results for the higher-order moments of the spin-3/2 baryons, including the electric-quadrupole moment E2 and the magnetic-octupole moment M3. The world's first determination of a nonzero M3 form factor for the {delta} baryon is presented. With these results we provide a conclusive analysis which shows that decuplet baryons are deformed. We compare the decuplet-baryon results from a similar lattice calculation of the octet baryons. We establish ...

International Nuclear Information System (INIS)

The Moessbauer emission spectrum of "2"4"1Am metal was investigated for influences of radiation self damage. Samples were kept continuously for 230 h at 4.2 K and spectra were taken each 10 to 20 h. No change in f-factor was observed, while the linewidth increased monotonically and reached saturation after approximately 180 h. The original width could be reproduced by a brief warming to room temperature. The increase in width reflects the change in quadrupole interaction due to the creation of lattice defects. The constancy of the f-factor indicates that the basic crystalline structure is retained.

International Nuclear Information System (INIS)

Ionic motion of a divalent cation, Ba"2"+, in a single crystal of Ba-Al-priderite was studied using "2"7Al as an NMR probe. Several pairs of satellite peaks due to electric quadrupole interaction were observed superposed on broad satellite tails on both sides of the main peak of "2"7Al. These peak pairs indicate the existence of some stable three-dimensional configurations of Ba"2"+ ions in the structure, and the broad shoulders show a random substitution of Al"3"+ for Ti"4"+ sites. The temperature dependence of the spin-lattice relaxation time T"*_l measured in the temperature range from 161 to 1176 K was analyzed by a curve fitting method on the assumption that there are two types of Ba"2"+ ions. An activation energy of 0.47 eV was obtained for the motion of Ba"2"+ ions which are easy to move, and a broad distribution of activation energies spread over a range from 0.95 to 2.45 eV was obtained for the motion of Ba"2"+ ions which form a ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

CERN Document Server

Tensor network states are used to approximate ground states of local Hamiltonians on a lattice in D spatial dimensions. Different types of tensor network states can be seen to generate different geometries. Matrix product states (MPS) in D=1 dimensions, as well as projected entangled pair states (PEPS) in D>1 dimensions, reproduce the D-dimensional physical geometry of the lattice model; in contrast, the multi-scale entanglement renormalization ansatz (MERA) generates a (D+1)-dimensional holographic geometry. Here we focus on homogeneous tensor networks, where all the tensors in the network are copies of the same tensor, and argue that certain structural properties of the resulting many-body states are preconditioned by the geometry of the tensor network and are therefore largely independent of the choice of variational parameters. Indeed, the asymptotic decay of correlations in homogeneous MPS and MERA for D=1 systems ...

International Nuclear Information System (INIS)

Anthracene-bis-resorcinol is an interesting molecule as it forms a hydrogen-bonded network when guest molecules with weak polarity are included. Focused ion beam (FIB) was irradiated on a part of its amorphous film with low dose, and the film was exposed to the vapor of guest molecules. From fluorescence and AFM analyses of this film, it was found that no inclusion compound was formed in FIB irradiated area, i.e. FIB irradiation suppresses the ability to form the inclusion compounds. By utilizing this phenomenon, we succeeded in a microfabrication of relief structures consisting of inclusion compounds which has different fluorescence from its surrounding. Morphology, fluorescence, and IR absorption analyses indicated that hydroxyl or resorcin groups are damaged by ion beams, and consequently a formation of hydrogen-bonded networks, which play a role of a lattice caging guest molecules, becomes impossible.

CERN Document Server

The design of a small injection linac for a compact medical synchrotron is discussed. The linac design is based on interdigital H-type (IH) drift-tube structure with alternative phase focusing (APhF). A high acceleration rate and an absence of magnetic lenses inside drift-tubes reduce the cost and length of APhF-IH linac in comparison with HIMAC linac based on Alvarez structure with magnet quadrupoles inside drift-tubes. To reduce effects of emittance growth, the RFQ structure is used in front of the APhF linac. In such linac layout, the current transmission of a carbon beam can reach up to 90-100%. In this report, the basic parameters of whole linac are presented, while the design of APhF structure is considered in details. Two reference designs of 4 MeV/u 200 MHz APhF linacs with different voltage distributions along the whole tank have been generated and analyzed numerically. For the first design, a constant voltage distribution along the ...

International Nuclear Information System (INIS)

... nuclear electric moments nuclear magnetic moments nuclear radii quadrupole

Energy Technology Data Exchange (ETDEWEB)

Longitudinal compression of space-charge dominated beams can be achieved by imposing a head-to-tail velocity tilt on the beam. This tilt has to be carefully tailored, such that it is removed by the longitudinal space-charge repulsion by the time the beam reaches the end of the drift compression section. The transverse focusing lattice should be designed such that all parts of the beam stay approximately matched, while the beam smoothly expands transversely to the larger beam radius needed in the final focus system following drift compression. In this thesis, several drift compression systems were designed within these constraints, based on a given desired pulse shape at the end of drift compression systems were designed within these constraints, based on a given desired pulse shape at the end of drift compression. The occurrence of mismatches due to a rapidly increasing current was analyzed. In addition, the sensitivity of ...

CERN Document Server

In the CLIC main linac it is very important to minimise the trajectory excursion and consequently the emittance dilution in order to obtain the required luminosity. Several algorithms have been proposed and lately the ballistic method has proved to be very effective. The trajectory method described in this Note retains the main advantages of the latter while adding some interesting features. It is based on the separation of the unknown variables like the quadrupole misalignments, the offset and slope of the injection straight line and the misalignments of the beam position monitors (BPM). This is achieved by referring the trajectory relatively to the injection line and not to the average pre-alignment line and by using two trajectories each corresponding to slightly different quadrupole strengths. A reference straight line is then derived onto which the beam is bent by a kick obtained by moving the first quadrupole. The ...

International Nuclear Information System (INIS)

This review describes the basic theory and some recently developed techniques for the study of quadrupole nuclei with half integer spins in powder materials. The latter is connected to the introduction of the double rotation (DOR) by A. Samoson et al. (1) and to the introduction of the multiple quantum magic-angle spinning (MQ MAS) technique by L. Frydman et. al. (2). For integer spins, especially the solid-state deuterium magnetic resonance, we refer to the review of G.L. Hoatson and R.L. Vold: ''"2H-NMR Spectroscopy of Solids and Liquid Crystals'' (3). For single crystals we refer to O. Kanert and M. Mehring: ''Static quadrupole effects in disordered cubic solids''(4) and we would like also to mention the ''classic'' review of M.H. Cohen and F. Reif: ''Quadrupole effects in NMR studies of solids'' (5). Some more recent reviews in the field under study are D. Freude and J. Haase ''Quadrupole effects in ...

CERN Document Server

The work identifies the first lattice decoding solution that achieves, in the general outage-limited MIMO setting and in the high-rate and high-SNR limit, both a vanishing gap to the error-performance of the (DMT optimal) exact solution of preprocessed lattice decoding, as well as a computational complexity that is subexponential in the number of codeword bits. The proposed solution employs lattice reduction (LR)-aided regularized (lattice) sphere decoding and proper timeout policies. These performance and complexity guarantees hold for most MIMO scenarios, all reasonable fading statistics, all channel dimensions and all full-rate lattice codes. In sharp contrast to the above manageable complexity, the complexity of other standard preprocessed lattice decoding solutions is shown here to be extremely high. Specifically the work is first to quantify the complexity ...

International Nuclear Information System (INIS)

As a three-year joint university-industry effort, development of a generalized boiling transition analysis method has been started in 2002 aiming at enhanced capabilities of subchannel analysis for a wide variety of BWR-type fuel bundle geometry from ordinary BWR to tight lattice fuel bundles. For this purpose, five dominant factors affecting boiling transition phenomena have been identified on which our efforts of experimentation and numerical analyses are focused. In this report, as the first-year achievement, we will describe a master plan of the development and contents for experimental approaches to construct thermal-hydraulic databases. The databases will be utilized for the developments of constitutive equations to describe the basic characteristics of the elementary processes. The planned experiments are divided into two groups. One is air-water experiments at atmospheric pressure, and the other is steam-water experiments up to 1 MPa. ...

International Nuclear Information System (INIS)

... chemical reactions high temperature lattice parameters microhardness

KoreaScience (Korea)

Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Solid molecular orthohydrogen exhibits orientational order at low temperatures. The orthohydrogen molecules, which are quadrupoles, order in the Pa3 structure. We have simulated this ordering, and explored the behaviour under dilution by spherical parahydrogen molecules.

Energy Technology Data Exchange (ETDEWEB)

We discuss the algebraic structure of the generator coordinate method for triaxial quadrupole collective motion. The collective solutions are classified according to the representations of the permutation group of the intrinsic axes. Our method amounts to an approximate angular-momentum projection. We apply it to a study of the spherical-to-deformed-shape transition in light even strontium isotopes {sup 78-88}Sr. We find that triaxial configurations play a significant role in explaining the structure of the transitional isotopes {sup 80-82}Sr. (orig.).

International Nuclear Information System (INIS)

Properties of unique parity states in odd-proton (_7_7Ir, _7_9Au) and odd-neutron nuclei (_7_8Pt) are investigated in the framework of the interacting boson-fermion approximation model. The core (boson)-particle (fermion) interaction is represented by a quadrupole-quadrupole interaction and an exchange term, which takes into account the effects of the Pauli exclusion principle. The even-even core nucleus is described in terms of the IBA-1 hamiltonian. The change in the properties of the corresponding odd-A nuclei can be interpreted in terms of a transition of the core hamiltonian between the O(6) and SU(3) limiting cases. (orig.).

UK PubMed Central (United Kingdom)

Spin-lattice relaxation rates of protein and water protons in dry and hydrated immobilized bovine serum albumin were measured in the range of ¹H Larmor frequency from 10 kHz to 30...Full Text Available

UK PubMed Central (United Kingdom)

PurposeTo report the clinical, ophthalmic, and genetic characteristics for lattice corneal dystrophy type I (LCDI) in a Chilean family.MethodsSix...Full Text Available

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

Interpenetrated lattices (IPL) are combinations of reticulated polymers linked together by permanent crisscross. This structure is well-adapted to combined highly incompatible pairs of polymers. The in-situ sequential method has been applied successfully to the synthesis of ethylene poly-oxides / poly-siloxanes IPLs. The results concerning the preparation of such lattices and their behaviour as solid polymer electrolytes are presented in this paper. (J.S.) 24 refs.

Energy Technology Data Exchange (ETDEWEB)

The decays of charmed mesons into two body nonleptonic final states are investigated. Weak interaction amplitudes of interest in these decays are extracted from lattice four-point correlation functions using a effective weak Hamiltonian including effects to order G{sub f} in the weak interactions yet containing effects to all orders in the strong interactions. The lattice calculation allows a quantitative examination of non-spectator processes in charm decays helping to elucidate the role of effects such as color coherence, final state interactions and the importance of the so called weak annihilation process. For D {yields} K{pi}, we find that the non-spectator weak annihilation diagram is not small, and we interpret this as evidence for large final state interactions. Moreover, there is indications of a resonance in the isospin {1/2} channel to which the weak annihilation process contributes exclusively. Findings from the ...

Energy Technology Data Exchange (ETDEWEB)

The linearized collective Schroedinger equation for nuclear quadrupole surface vibrations incorporates a new spin degree of freeedom with a spin value of 3/2. We use this equation to describe the low energy spectrum of certain even-odd Ir nuclei which have a spin 3/2 in their ground state. For that purpose we explicitly introduce collective spin-dependent potentials which simulate the interaction of the valence nucleon with the core. The linearized Schroedinger equation is transformed into an effective Schroedinger equation with collective spin-dependent potentials. Already collective spin-orbit couplings of SO(3) and SO(5) type are sufficient to reproduce the lowest excited states of even-odd Ir nuclei. (orig.).

British Library Electronic Table of Contents (United Kingdom)

We investigate two routes to obtain negative group velocity bands in two-dimensional phononic crystal structures. The negative dispersion originates from the resonances of sub-wavelength building blocks and as such, the system should be regarded as acoustic metamaterials. The first kind of acoustic metamaterial exhibits effectively negative bulk modulus and negative mass density simultaneously. Monopolar and dipolar Mie resonances are combined to achieve an effective medium with negative refractive index. In particular, we present a double negative metamaterial for airborne sonic waves. We then show that we can obtain negative group velocity from quadrupole resonances, and the result is explained using the quasi-static approximation. The negative dispersion in quadrupole bands cannot be de...

CERN Document Server

The Large Hadron Collider (LHC) will be equipped with several thousands of superconducting corrector magnets. Among the largest ones are the superconducting trim quadrupoles (MQTL). These twin-aperture magnets with a total mass of up to 1700 kg have a nominal gradient of 129 T/m at 1.9 K and a magnetic length of 1.3 m. Sixty MQTL are required for the LHC, 36 operating at 1.9 K in and 24 operating at 4.5 K. The paper describes the design features, and reports the measured quench performance and magnetic field quality of the production magnets. The MQTL magnet production is shared between CERN and industry. This sharing is simplified due to the modular construction, common to all twin-aperture correctors.

International Nuclear Information System (INIS)

We investigate a two-orbital Anderson lattice model with Ising orbital intersite exchange interactions on the basis of a dynamical mean field theory combined with the static mean field approximation of intersite orbital interactions. Focusing on Ce-based heavy-fermion compounds, we examine the orbital crossover between two orbital states, when the total f-electron number per site n_f is #approx#1. We show that a 'meta-orbital' transition, at which the occupancy of two orbitals changes steeply, occurs when the hybridization between the ground-state f-electron orbital and conduction electrons is smaller than that between the excited f-electron orbital and conduction electrons at low pressures. Near the meta-orbital critical end point, orbital fluctuations are enhanced and couple with charge fluctuations. A critical theory of meta-orbital fluctuations is also developed by applying the self-consistent renormalization theory of itinerant electron ...

International Nuclear Information System (INIS)

One of the hallmarks of linear coupling is the resonant exchange of oscillation amplitude between the horizontal and vertical planes when the difference between the unperturbed tunes is close to an integer. The standard derivation of this phenomenon (known as the difference resonance) can be found, for example, in the classic papers of Guignard [1, 2]. One starts with an uncoupled lattice and adds a linear perturbation that couples the two planes. The equations of motion are expressed in hamiltonian form. As the difference between the unperturbed tunes approaches an integer, one finds that the perturbing terms in the hamiltonian can be divided into terms that oscillate slowly and ones that oscillate rapidly. The rapidly oscillating terms are discarded or transformed to higher order with an appropriate canonical transformation. The resulting approximate hamiltonian gives equations of motion that clearly exhibit the exchange of oscillation amplitude between the two ...

International Nuclear Information System (INIS)

A numerically feasible method, based on the use of deformed phonons, is developed for the diagonalization of the collective quadrupole Hamiltonian for a system with an odd particle coupled to an anharmonic even core. Examples: the transition from prolate to oblate via #gamma#-unstable shapes and furthermore the hsub(9/2) spectra of the nuclei "1"8"7Ir and "1"9"7Tl. (Auth.).

International Nuclear Information System (INIS)

The MOS-technology allows to make tiny electronic lenses for multibeam electron systems. In the paper results of research and principles of designing of tiny magnetic electron lenses are submitted. Electronic lenses with a nonconventional configuration of tiny magnetic circuit and electronic lenses with coincident electric and magnetic fields in nonconventional tiny performance are considered

Energy Technology Data Exchange (ETDEWEB)

Horizontal beam orbit jitter at frequencies around 10 Hz has been observed in RHIC for several years. The distinct frequencies of this jitter have been found at superconducting low-beta quadrupole triplets around the ring, where they coincide with mechanical modes of the cold masses. Recently, we have identified liquid helium flow as the driving force of these oscillations.

CERN Document Server

Dimensional metrology and positioning operations are used in many fields of particle accelerator projects. This lecture gives the basic tools to designers in the field of measure by analysing the spatial layout of measurement systems since it is central to dimensional metrology as well as positioning operations. In a second part, a case study dedicated to a synchrotron storage ring is proposed from the detection of the magnetic centre of quadrupoles to the orbit definition of the ring.

CERN Document Server

The dynamics of spin-lattice relaxation (slr) of metal-organic Pt(II) compounds is studied. Often, such systems are characterized by pronounced zero-field splittings (zfs) of the lowest-lying triplets. Previous expressions for the Orbach slr process do not allow to treat such splitting patterns properly. We discuss the behavior of a modified Orbach expression for a model system and present results of a fit of the temperature dependence of the spin-lattice relaxation rate of Pt(2-thpy)$_2$ based on the modified expression.

International Nuclear Information System (INIS)

Augmented plane wave calculation of gadolinium electronic structure crystallized in a hexagonal close-packed lattice is carried out.

CERN Document Server

In this paper we establish a fundamental structural result for formal series encoding the total non-archimedean masses of quadratic lattices of varying determinant squareclasses, but with fixed rank $n$ and signature over any fixed number field. We conclude with some local computations for $n=2$, and use these to derive an analytic class number formula for CM extensions.

Energy Technology Data Exchange (ETDEWEB)

X-ray results on the lattice parameters, molar volume and thermal expansion coefficients of solid ortho-deuterium for the region from 2 K to the melting point are reported. It is found that the thermal expansion of ortho-deuterium crystals, similarly to parahydrogen is essentially anisotropic near the melting temperature. The vacancy density at the triple point is estimated. Some thermodynamic characteristics of ortho-deuterium are calculated and temperature dependences of heat capacity at constant volume, isothermal compressibility and Gruneisen constant are analyzed.

International Nuclear Information System (INIS)

Based on theoretical calculations of powder diffraction data it is shown that the assumption of the infinite crystal lattice for small particles is not justified, leads to significant changes of the diffraction patterns, and may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called 'apparent lattice parameter', alp, is proposed. (author)

International Nuclear Information System (INIS)

Critical power characteristics of tight lattice rod assembly was investigated using a simple-shaped experimental apparatus. An electrically heated rod with four spacers was placed in a circular tube, and boiling transition condition for a rod in an annular geometry was clarified varing annulus clearance. It was found that critical heat flux depends strongly on the clearance accoding as the gap becomes smaller. This results was compared with KfK correlation and the trends were well correlated. (author).

Energy Technology Data Exchange (ETDEWEB)

The Schroedinger equation for nuclear quadruple surface vibrations is linearized with the consequence that a new spin degree of freedom appears in the wave function of the linearized equation. This spin is called collective spin and has a value of 3/2. The linearized Schroedinger equation for quadrupole vibrations is used for the description of certain collective aspects of even-odd {sup 187,189,191}Ir nuclei which have a spin 3/2 in their ground state. As a potential we use the {gamma}-soft collective potential of the neighboring even-even nuclei, which is inserted into the linearized Schroedinger equation via a scalar coupling. This leads to a collective spin-dependent fine structure splitting of the energy levels governed by a collective SO(5) spin-orbit coupling and a correction to the kinetic energy. Further, we consider explicitly spin-dependent potentials which effectively describe the interaction of the valence nucleon with the core of the even-odd Ir ...

British Library Electronic Table of Contents (United Kingdom)

We describe a method for the analysis of multi-site phosphorylation in serine/threonine (Ser/Thr)-rich protein sequences. Site-specific mutagenesis was used to introduce tryptic cleavage sites in the serine glutamine/threonine glutamine cluster domain (SCD) of the human checkpoint protein kinase (Chk2). The mutant proteins were shown to autophosphorylate on residues that are inducibly phosphorylated when mammalian cells are exposed to ionizing radiation (serine 33/35, serine 516, threonine 68 and threonine 432). Five Ser/Thr clusters within the SCD were flanked by arginine or lysine residues to produce tryptic peptides for nanospray liquid chromatography (nanoLC)/linear quadrupole ion trap Fourier transform ion cyclotron resonance mass spectrometry. Phosphorylation sites were assigned usin...

International Nuclear Information System (INIS)

A variable-dispersion electron spectrometer is being installed for use by the Stanford Superconducting Accelerator in conjunction with its Free Electron Laser program. The system has been designed to operate with electron beam energies from 20 MeV to 200 MeV, with a maximum energy resolution of 0.01% FWHM. The maximum energy acceptance is approximately #+-# 5%, as determined by the bending magnet aperture. Resolution is controlled by adjusting the focal conditions at the entrance to a 90 degree bending magnet, while the dispersion is controlled by changing the magnitude and polarity of the field in a quadrupole magnet which immediately follows the bending magnet. 4 refs., 5 figs.

Science.gov (United States)

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

Energy Technology Data Exchange (ETDEWEB)

Solenoid transport of high current, heavy ion beams is considered for several stages of a heavy ion fusion driver. In general this option is more efficient than magnetic quadrupole transport at sufficiently low kinetic energy and/or large e/m, and for this reason it has been employed in electron induction linacs. Ideally an ion beam would be transported in a state of Brillouin flow, i.e. cold in the transverse plane and spinning at one half the cyclotron frequency. The design of appropriate solenoids and the equilibrium and stability of transported ion beams are discussed. An outline of application to a fusion driver is also presented.

Energy Technology Data Exchange (ETDEWEB)

CERN has encouraged the US-LARP collaboration to participate in Phase I of the LHC luminosity upgrade by analyzing the benefits gained by using Nb3Sn technology to replace the functionality of select NbTi magnets that CERN is committed to construct. Early studies have shown that the much higher gradients (shorter magnetic lengths) and temperature margins (quench stability) of Nb3Sn magnets compared to their NbTi counterparts is favorable--allowing the insertion of additional absorbers between Q1 and Q2, for example. This paper discusses the relative merits of the NbTi and Nb3Sn options.

Energy Technology Data Exchange (ETDEWEB)

A model of a solid disordered ortho-parahydrogen mixture with infinite long-range interaction J/sub ij/ between orthomolecules distributed in accordance with a normal law with first moment J/sub 0/ is investigated. It is shown that the introduction of an external electric field gradient ..gamma.. can give rise to a phase transition to an orientational phase. The possible existence of an orientational glass phase is established. The influence of the degeneracy of the hydrogen orthomolecules on the low-temperature thermal properties of these systems is demonstrated, and a condition of stability of the replica-symmetric solution is established. At low temperatures, this solution is stable for a large value of ..gamma.. or J/sub 0/.nctio

International Nuclear Information System (INIS)

Lifetimes have been measured in the #pi#h_9_/_2 (yrast) and #pi#i_1_3_/_2 (excited) bands in the nuclei "1"8"1Ir and "1"8"7Au using the Recoil Distance Method (RDM). The results clearly indicate that the #pi#i_1_3_/_2 band exhibits an increased deformation over the #pi#h_9_/_2 band, in keeping with the premise that the delayed crossing in this band is due to enhanced quadrupole deformation. (author). 3 refs, 1 fig, 2 tab.

Energy Technology Data Exchange (ETDEWEB)

The requirements for transporting high-current, negative-ion beams are presented with particular emphasis on applications involving negative-hydrogen-ion beams. In addition to the usual matching and steering problems, particular attention must be paid to beam emittance growth in the transport system. Depending on the application, a number of approaches have been developed using both magnetic and electric lenses. I discuss the design considerations for transporting and matching these beams to radio-frequency quadrupole accelerators, and present a survey of the various types of beamlines now used for negative-ion beams.

Science.gov (United States)

We discuss elastic electron-deuteron (ed) scattering beyond the Born approximation. The reaction amplitude contains six generalized form factors, but only three linearly independent combinations of them (generalized charge, quadrupole, and magnetic form factors) contribute to the reaction cross section in second-order perturbation theory. We examine the two-photon exchange and find that it includes two types of diagrams, where two virtual photons are interacting with the same nucleon and where the photons are interacting with different nucleons. It is shown that the two-photon-exchange amplitude is strongly connected with the deuteron wave function at short distances.

Energy Technology Data Exchange (ETDEWEB)

The structure of the low-lying levels of the [sup 91]Zr nucleus is discussed in a framework of the cluster-phonon coupling model. In order to describe simultaneously positive- and negative-parity states, octupole as well as quadrupole vibrations of the [sup 88]Sr core are allowed. The cluster states include two single protons coupled to a single neutron. The residual interaction among the cluster particles is assumed to be the modified surface [delta] interaction. Energy levels and electromagnetic properties are calculated and compared with the experimental data.

Energy Technology Data Exchange (ETDEWEB)

Differential cross sections have been measured for the elastic and inelastic scattering of 104 MeV alpha-particles from /sup 90/,/sup 92/Zr. The experimental data are analyzed in terms of coupled channels on the basis of a flexible anharmonic vibrator model and using different parametrizations of the radial shape of the extended optical potential. The results favour the squared Saxon-Woods type for the real part. Additionally to a radial momentum analysis of the real potentials a semimicroscopic folding model has been invoked for extracting isoscalar quadrupole and hexadecapole transition rates.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

Future insertion quadrupoles with large apertures and high gradients will be required for the Phase II luminosity upgrade (10{sup 35} cm{sup -2}s{sup -1}) of the Large Hadron Collider (LHC). Although improved designs, based on NbTi, are being considered as an intermediate step for the Phase I upgrade, the Nb{sub 3}Sn conductor is presently the best option that meets the ultimate performance goals for both operating field and temperature margin. As part of the development of Nb{sub 3}Sn magnet technology, the LHC Accelerator Research Program (LARP) developed and tested several 1-meter long, 90-mm aperture Nb{sub 3}Sn quadrupoles. The first two series of magnet used OST MJR 54/61 (TQ01 series) and OST RRP 54/61 (TQ02 series) strands. The third series (TQ03) used OST RRP 108/127 conductor. The larger number of sub-elements and the consequent reduction of the effective filament size, together with an increased fraction of copper and a lower Jc were ...

British Library Electronic Table of Contents (United Kingdom)

Strut lattice structures of reaction-bonded silicon infiltrated silicon carbide ceramics (RB-SiSiC) for air-fuel mixture formation and for nonstationary lean-burn under pressure applications were fabricated. The lattice design with a high porosity >80% was shaped by indirect three-dimensional printing. It was shown that pre-ignition processes in the porous reactor are much faster than in a free combustion, especially at lower temperatures. Interaction of high velocity diesel jets with cylindrical strut ligaments of the SiSiC lattice structure offers a new possibility for quick and efficient fuel distribution (multi-jet splitting) in space.

Energy Technology Data Exchange (ETDEWEB)

In CsCdBr{sub 3}, Tm{sup 3+} substitutes for Cd{sup 2+}. It predominately forms symmetric dimer centers and single-ion centers, both of trigonal symmetry. The energy level schemes of both centers were determined by EPR and site-selective laser spectroscopy. To describe the spectra term dependent crystal-field parameters were deduced on the basis of a microscopic model taking into account the local lattice deformation induced by the impurity centers and the quasi-resonant virtual scattering of intrinsic lattice excitations by the Tm{sup 3+} ions. (orig.) 22 refs.

CERN Document Server

In this paper we have studied the relation between the intutionistic fuzzy left (respectively right) ideals of {\\Gamma}-semiring and that of operator semiring. Thereafter, we have established that the Lattices of all intutionistic fuzzy left (respectively right) ideal of {\\Gamma}-semiring is equivalent to that of Left operator semiring. We proved that Then there exist an inclusion preserving bijection ({\\mu}_{A,}\\u{psion}_{A})$\\rightarrow$({\\mu}_{B}^{+'},\\u{psion}_{B}^{+'}) between the lattices of all intuitionistic fuzzy right ideals (respectively intuitionistic fuzzy ideals) of S and the lattices of all intuitionistic fuzzy right ideals (respectively intuitionistic fuzzy ideals) of L. Where ({\\mu}_{A},\\u{psion}_{A}) is an intuitionistic fuzzy right (respectively intuitionistic fuzzy ideals) ideal of S. Also we have established few properties relating the k-ideals and h-ideals of {\\Gamma}-semiring with that of ...

International Nuclear Information System (INIS)

The effect of lattice damage caused by room temperature irradiations with products of "1"0B(n,#alpha#)"7Li reactions and "2"3"5U fissions and with fast neutrons on transition curves, quenching curves, and lattice constants of Nb_3Sn, Nb_3Al, Nb_3(Al,Ge), and V_3Si have been investigated. The critical currents in transverse magnetic fields could be increased up to more than one order of magnitude. For heavily irradiated samples drastically reduced values for the critical currents, the upper critical fields, and the transition temperatures were observed. The lattice constants were increased up to 0.5 percent by irradiation. (U.S.).

Energy Technology Data Exchange (ETDEWEB)

Rafting of the {gamma}/{gamma}{prime} morphology of nickel-base superalloys is a well-known phenomenon during high-temperature deformation. The initial stages of this type of directional coarsening were modeled two-dimensionally by the method of finite elements (FEs) using an energy-perturbation approach. In addition to the elastic energy density, the effect of the local difference of the hydrostatic stresses in {gamma} and {gamma}{prime} in combination with the different lattice parameters of the two phases was considered in the calculations as a further driving force. From the results of modeling, the deformation-induced internal stresses and strains were determined and used to evaluate the direction-dependent lattice parameters and lattice misfits of the two phases. The results agree well with experimentally determined values.

International Nuclear Information System (INIS)

Experimental data on A-15 binary phases (the lattice parameter dependence on composition, phase diagrams, etc.) have been considered and the so-called ''compounds with A-15 structure'' are shown to be solid solutions of element substitution in the structure of A-15 type. Values of lattice parameter and atomic volume of A-15 modifications for 21 elements have been obtained (for Zr, W, Nb, Mo, V in particular). There has been shown the possibility of calculation of atomic volumes and lattice parameters of A-15 binary phases at the lack of direct experimental data. The essential role of atomic volume relations of different phases has been observed for the estimation of stability conditions of A-15 phase.

British Library Electronic Table of Contents (United Kingdom)

The languages of the world exhibit a range of formal phenomena (e.g. accenting, syntactic reordering and morphological marking) that are commonly linked to the information-structural notion of focus. Crucially, there does not seem to be a one-to-one mapping between particular formal features (focus marking devices) and focus, neither from a cross-linguistic perspective, nor within individual languages. This raises the question of what is actually being expressed if we say that a constituent is focused in a particular language, and whether, or to what extent, the same semantic or pragmatic content is formally expressed by focus-marking across languages. This special issue addresses the question of focus and its grammatical realization from a number of theoretical and empirical perspectives....

Energy Technology Data Exchange (ETDEWEB)

I present results for the mass spectrum of excited baryons and pentaquarks using overlap fermions and Bayesian curve-fitting method; and magnetic moments and polarizabilities for a variety of hadrons in the background field method.

CERN Document Server

We calculate the light `glueball' mass spectrum in N_f=2 lattice QCD using a fermion action that is non--perturbatively O(a) improved. We work at lattice spacings a~0.1 fm and with quark masses that range down to about half the strange quark mass. We find the statistical errors to be moderate and under control on relatively small ensembles. We compare our mass spectrum to that of quenched QCD at the same value of a. Whilst the tensor mass is the same (within errors), the scalar mass is significantly lighter in the dynamical lattice theory, by a factor of ~0.84 +/- 0.03. We discuss what the observed m_q dependence of this suppression tells us about the dynamics of glueballs in QCD. We also calculate the masses of flux tubes that wind around the spatial torus, and extract the string tension from these. As we decrease the quark mass we see a small but growing vacuum expectation value for the corresponding flux tube operators. ...

CERN Document Server

Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, $m_s$, $m_u$, and $m_d$, respectively. Perturbative matching is required in order to connect the lattice-regularized bare- quark masses to the masses as defined in the \\msbar scheme, and this is done here for the first time at next-to-next-to leading (or two-loop) order. The bare-quark masses required as input come from simulations by the MILC collaboration of a highly-efficient formalism (using so-called ``staggered'' quarks), with three flavors of light quarks in the Dirac sea; these simulations were previously analyzed in a joint study by the HPQCD and MILC collaborations, using degenerate $u$ and $d$ quarks, with masses as low as $m_s/8$, and two values of the lattice spacing, with chiral extrapolation/interpolation to the physical masses. With the ...

International Nuclear Information System (INIS)

A brief review is given of the nature of lattice instabilities in high-T/sub c/ superconductors. The Frohlich instability in A-15 compounds is indicated to be a microdomain which acts as an embryo for the Martensitic transformations in these compounds.

Science.gov (United States)

The purpose of this communication is to determine whether the solubility enhancements for cold-worked Pd-Ni alloys increase or decrease with atom fraction of Ni. Substitutional Ni atoms contract and Pd lattice, in contrast to the lattice expansion resulting from substitutional Ag in Pd. The Pd-Ni alloy system forms a continuous series of fcc solid solution alloys over the whole composition range. The solubility enhancements will also be determined for a series of homogeneous, ternary Pd[sub 1[minus]x]Ni[sub 1/2x]Ag[sub 1/2x] alloys for x in the range from 0 to 0.2. For this series of ternary alloys the fcc lattice parameters do not change significantly from that of pure Pd. The alloys used in this research were purchased from Tanaka Kikinzoku Kogyo K.K. The detailed experimental procedure has been described previously. The alloys were all deformed by cold-rolling ca 90%. Both the binary and ternary alloys showed only single ...

Energy Technology Data Exchange (ETDEWEB)

In this paper we discuss the effect on the emittance of the residual dispersion in the insertion devices. The dispersion in the straights could be generated by the lattice error, trim dipole, and insertion device. The effect on the emittance is examined, and the dispersion tolerances are given for the NSLS-11.

International Nuclear Information System (INIS)

A transient-enhanced diffusion has been observed during the furnace or rapid thermal annealing of As-implanted Si. The relations of the enhanced diffusion to residual defects and lattice restoration have been studied in detail. The As concentration profiles and residual defects are measured. It is found from the data that the lattice has been restored when the implanted sample is annealed at 1150 deg C (or 1050 deg C) for 1s. The defect density decreases rapidly with increase of annealing time (from 1 to 12s). The enhanced diffusion coefficient maximum appears in the annealing time ranging from 1 to 5s. Allmost a 'complete' annealing of displacemet damage is obtained and the diffusion coefficient is less than that in above-mentioned conditions when the implanted samples are annealed at 1150 deg C in the time ranging from 12 to 20s. the mechanism of lattice restoration and enhanced diffusion in annealing process have been ...

Energy Technology Data Exchange (ETDEWEB)

It is shown that when a quantum mechanical oscillator is parametrically excited there are special values of the parameters for which the system will pass periodically through a lattice of coherent states associated with the modular group [Gamma]. It is shown that these [Gamma] transits can be used to determine unknown parameters. A method is given for detecting the transits experimentally and is made possible by the existence of three families of states associated with modular forms that are orthogonal to the lattice. For isotropic states the three families occur in [ital D]-mode systems with [ital D][gt]10, 14, and 26.

Energy Technology Data Exchange (ETDEWEB)

Quark-hadron duality and its potential applications are discussed. We focus on theoretical efforts to model duality.

Energy Technology Data Exchange (ETDEWEB)

This report summarizes current status of an R&D program to develop a focusing system for the front end of a superconducting RF linac. Superconducting solenoids will be used as focusing lenses in the low energy accelerating sections of the front end. The development of focusing lenses for the first accelerating section is in the production stage, and lens certification activities are in preparation at FNAL. The report contains information about the focusing lens design and performance, including solenoid, dipole corrector, and power leads, and about cryogenic system design and performance. It also describes the lens magnetic axis position measurement technique and discusses scope of an acceptance/certification process.

International Nuclear Information System (INIS)

The analysis of elastic and inelastic scattering of #alpha# particles with energy of 50 MeV by nuclei with mass numbers A=54-124 and of "3He particles by the nucleus "6"4Ni is given in the framework of the optical model. The parameters of multipole deformations for lower states are determined. The parameters for quadrupole and octupole deformations of the potential for the nucleus "1"1"2Sn are extracted, the values of the hexadecupole deformation #beta#_4 of the potential for nuclei "9"4Zr, "1"2"0","1"2"4Sn are found. Information is extracted on the ratio of deformation parameters for the neutron and proton components in lower collective states (2_1"+, 3_1"-) of nuclei with A=90-124.

Energy Technology Data Exchange (ETDEWEB)

Elastic and inelastic proton scattering has been measured in inverse kinematics on the unstable nucleus {sup 40}S. A phenomenological DWBA analysis yields a quadrupole deformation parameter {beta}{sub 2} = 0.35 {+-} 0.05 for the 2{sup +}{sub 1} state. Consistent phenomenological and microscopic proton scattering analyses have been applied to all even-even Sulfur isotopes from A = 32 to A = 40. The microscopic analysis used microscopic collective model densities and a modified Jeukenne-Lejeune-Mahaux effective interaction. This analysis suggests the presence of a neutron skin in the heavy sulfur isotopes. The analysis is consistent with normalization values for {lambda}{sub {upsilon}} and {lambda}{sub {omega}} of 0.95 for both the real and imaginary parts of the JLM potential. (author)

British Library Electronic Table of Contents (United Kingdom)

The crystal structure of Ca2RuD6 has been determined by neutron powder diffraction: space group Fm3m, K2PtCl6 structure, as found for other hexahydride salts of group 8 metals with alkaline earth or lanthanide counter ions. No structural phase transition was observed between 340K and 50K. The deuterium nuclear quadrupole coupling constant, 54.7kHz, leads to an ionic character of the Ru-D bond of 76%. The known trends in the behaviour of A2MH6 salts are interpreted in terms of the ionization energies of the cation and the central metal atom.

International Nuclear Information System (INIS)

Measurements are made on the principal magnetic susceptibilities and anisotropies of praseodymium selenate octahydrate single crystals in the temperature range 90 to 300 K. Although the effective magnetic moment is close to the free ion value, the anisotropy is quite high at room temperature. A least sequares fit of the Curie-Weiss law to the observed average susceptibility yields -36.5 K as the paramagnetic Curie temperature. An analysis of the results with a crystal field (CF) of D_4 symmetry, explains the observed results quite well. The CF and the spin-orbit interaction matrix is block diagonalized in the complete 33 dimensional basis of the "3H term in order to obtain the Stark energies and their eigenstates. Intermediate coupling effects are also considered. The ground state being a singlet, the g-factors are absent. Some predictions on the electronic heat capacity and the electronic quadrupole splitting are made in the light of the proposed CF. (author).

Energy Technology Data Exchange (ETDEWEB)

An apparatus for non-invasively inspecting an object, such as an item of luggage, for explosives material is described. It comprises a multi-channel thermal neutron inspection system having a plurality of neutron irradiation chambers. Simultaneous operation of several channels increases the maximum system throughput several times. Each chamber has a lithium neutron source which is stimulated to neutron production by a proton beam. Beam switching magnets are energised by pulsing to divert a common proton beam to each source in turn. The initial beam is generated by a radio frequency quadrupole accelerator. The advantages of this system are very low residual source activity and controllable neutron production thereby minimising safety hazards. The irradiation chamber may contain several different gamma ray detectors to identify the elements present in explosives material. In addition, a neutron radiography imaging means may be employed to identify the presence of ...

Energy Technology Data Exchange (ETDEWEB)

A sensitivity study that used the particle tracking code PARMELA was performed on the Advanced Free-Electron Laser (AFEL). The tolerances on the alignment of the beam-line elements and the magnetic-field strengths were examined. Two base-line configurations were determined at the beginning of the study. The electron beam was then matched into the wiggler. The optimized beam-line parameters were varied independently and their sensitivities were judged with the criterion that the free-electron laser (FEL) effective-detuning parameter should not fluctuate more than 10%. The results of this study set the specifications for the alignment, for the sensitivity of the steering magnets, and for the accuracy of the magnetic field in the quadrupoles and dipoles. 5 figs., 3 figs., 3 tabs.

CERN Document Server

Two-dimensional simulations of the coarsening process of the isotropic/smectic-A phase transition are presented using a high-order Landau-de Gennes type free energy model. Defect annihilation laws for smectic disclinations, elementary dislocations, and total dislocation content are determined. The computed evolution of the orientational correlation length and disclination density is found to be in agreement with previous experimental observations showing that disclination interactions dominate the coarsening process. The mechanism of smectic disclination movement, limited by the absorption and emission of elementary dislocations, is found to be facilitated by curvature walls connecting interacting disclinations. At intermediate times in the coarsening process, split-core dislocation formation and interactions displaying an effective disclination quadrupole configuration are observed. This work provides the framework for further understanding of the formation and ...

Science.gov (United States)

Investigations have been conducted to determine the feasibility of using collisional cooling for reducing the energy spreads and, consequently, the emittances of negative-ion beams. We have designed a gas-filled RF-quadrupole ion cooler equipped with provisions for retarding energetic negative ion beams to energies below thresholds for electron detachment at injection and for re-acceleration to high energies after the cooling process. The device has been used to cool O{sup -} and F{sup -} ion beams with initial energy spreads, {Delta}E > 10 eV to final energy spreads, {Delta}E {approx} 2 eV FWHM. Overall transmission efficiencies of {approx}14% for F{sup -} beams have been obtained. Experimental results show that electron detachment is the major loss mechanism for negative ions.

British Library Electronic Table of Contents (United Kingdom)

Abstract Electronic structures of two representative zigzag and armchair models of aluminum phosphide nanotube (AlPNT) were investigated by density functional theory calculations. The structures were optimized and the bond lengths, tip diameters, band gaps, and dipole moments were calculated. Moreover, the quadrupole coupling constants (CQ) were calculated for the Al-27 atoms of the optimized structures. The same values of AlP bond lengths were calculated for both models. The larger value of band gap of armchair model than the zigzag model indicated the stronger dielectric property for the former model. The values of CQ(27Al) were the largest for the Al atoms placed at the tips of both zigzag and armchair AlPNT than other Al atoms, which could reveal dominant role of the Al atoms placed at...

International Nuclear Information System (INIS)

Nanocrystalline samples of Fe_8_0Mo_2_0 and Fe_5_0Mo_5_0 alloys were prepared by the mechanical milling method. The structure, lattice parameters, and crystallite size were determined by the X-ray diffraction. The magnetic properties of the milled products were determined by the Moessbauer spectroscopy. It was observed that in the case of the Fe_8_0Mo_2_0 alloy a solid solution of Mo in Fe was formed with the lattice parameters of the Fe increasing from 0.28659 nm to 0.29240 nm and the crystallite size decreasing from 250 nm to 20 nm. In the case of the Fe_5_0Mo_5_0 alloy there were no clear changes in values of the lattice parameters of Fe and Mo during the milling process, but the crystallite size decreased from 200 to 15 nm. Moessbauer spectra revealed different magnetic phases in the machanosynthesized Fe_Mo samples. In the case of the Fe_8_0Mo_2_0 alloy, the spectrum for the milled mixture indicated the formation of ...

Energy Technology Data Exchange (ETDEWEB)

Using the constrained-curve fitting method and overlap fermions with the lowest pion mass at 180 MeV, we observe that the masses of the first positive and negative parity excited states of the nucleon tend to cross over as the quark masses are taken to the chiral limit. Both results at the physical pion mass agree with the experimental values of the Roper resonance (N{sup 1/2+}(1440)) and S{sub 11} (N{sup 1/2-}(1535)). This is seen for the first time in a lattice QCD calculation. These results are obtained on a quenched Iwasaki 16{sup 3}x28 lattice with a=0.2 fm. We also extract the ghost {eta}{sup '}N states (a quenched artifact) which are shown to decouple from the nucleon interpolation field above m{sub {pi}}{approx}300 MeV. From the quark mass dependence of these states in the chiral region, we conclude that spontaneously broken chiral symmetry dictates the dynamics of light quarks in the nucleon.

Energy Technology Data Exchange (ETDEWEB)

Using the constrained curve fitting method and overlap fermions with the lowest pion mass at 180 MeV, we observe that the masses of the first positive and negative parity excited states of the nucleon tend to cross over as the quark masses are taken to the chiral limit. Both results at the physical pion mass agree with the experimental values of the Roper resonance (N{sup 1/2+} (1440)) and S{sub 11} (N{sup 1/2-}(1535)). This is seen for the first time in a lattice QCD calculation. These results are obtained on a quenched Iwasaki 16{sup 3} x 28 lattice with a = 0.2 fm. We also extract the ghost {eta}{prime} N states (a quenched artifact) which are shown to decouple from the nucleon interpolation field above m{sub {pi}} {approx} 300 MeV. From the quark mass dependence of these states in the chiral region, we conclude that spontaneously broken chiral symmetry dictates the dynamics of light quarks in the nucleon.

Energy Technology Data Exchange (ETDEWEB)

The oxidative dehydrodimerization of propylene to C/sub 3/-dimers (1,5-hexadiene and benzene) has been examined at 600/sup 0/C and atmospheric pressure using a (Bi/sub 2/O/sub 3/)/sub 0.85/(La/sub 2/O/sub 3/)/sub 0.15/ oxide ion-conducting catalyst in a reactor where a catalyst disk separates a feed of propylene in helium from air. The surface of the disk exposed to propylene was reoxidized not by gaseous O/sub 2/, but by the dissociative adsorption and reduction of dioxygen at the oxidant side of the disk, followed by oxide ion conduction to replace spent lattice oxygen. Selectivity to C/sub 3/-dimers when using lattice oxide migration to reoxidize the catalyst was considerably greater than when O/sub 2/ was added to the propylene feed under the same reaction conditions. This result supports the proposal that lattice oxygen is predominantly involved in the selective oxidation of propylene to C/sub 3/-dimers, and ...

Energy Technology Data Exchange (ETDEWEB)

Vanadium doped manganese bi-oxide has been obtained from a solution containing both cations. The X-ray diffraction of this material indicates a rutile-type phase but the enlargement of some lines supports the existence of several lattice defects. Also the particle size of the doped material is significantly smaller than the one of the non-doped material obtained in the same conditions. The presence of pentavalent vanadium inside the lattice leads to a small amount of trivalent manganese. Electron microscopy shows the existence of defects which have a tendency of becoming well-ordered and to stabilize a sur-structure. At ambient temperature, the electrochemical behaviour of doped manganese bi-oxide is greatly improved when compared to the non-doped phase. This behaviour is due to the presence of numerous lattice defects and to the smaller size of crystallites. In polymer batteries, the behaviour is similar the one of the ...

CERN Document Server

We show how to obtain a fast component-by-component construction algorithm for higher order polynomial lattice rules. Such rules are useful for multivariate quadrature of high-dimensional smooth functions over the unit cube as they achieve the near optimal order of convergence. The main problem addressed in this paper is to find an efficient way of computing the worst-case error. A general algorithm is presented and explicit expressions for base~2 are given. To obtain an efficient component-by-component construction algorithm we exploit the structure of the underlying cyclic group. We compare our new higher order multivariate quadrature rules to existing quadrature rules based on higher order digital nets by computing their worst-case error. These numerical results show that the higher order polynomial lattice rules improve upon the known constructions of quasi-Monte Carlo rules based on higher order digital nets.

International Nuclear Information System (INIS)

X-ray magnetic diffraction (XMD) technique was applied to an orbital ordering compound of ferromagnetic YTiO_3 for the first time. The orbital-magnetic form factor #mu# _L(k) and the spin-magnetic form factor #mu# _S(k) were independently measured by utilizing the LS separation ability of the XMD. The #mu# _L(k) was measured for ten reciprocal-lattice points. No significant values of the #mu# _L(k) were observed for most of the reciprocal-lattice points within the estimated statistical errors, which suggested quenching of the orbital moment. The #mu# _S(k) was measured for 22 reciprocal-lattice points. Fourier synthesis of the #mu# _S(k) gave the spin density distribution m _S(r) in the real space. The obtained m _S(r) map shows the characteristic feature of the electron distribution of 3d electron in the t_2_g state of a Ti atom coordinated by O"2"- ions, in which the electrons are distributed away from the negative O"2"- ...

International Nuclear Information System (INIS)

With "1"5"1Eu-Moessbauer spectroscopy and other methods the complex magnetic properties of Eu_2PdSi_3, arising from the two crystallographically different lattice sites of the Eu"2"+ ions, have been already studied. Here we study the impact of magnetic dilution of the magnetic Eu"2"+ sites by non-magnetic Y"3"+ ions. A previous specific heat study has found reduced magnetic ordering temperatures with strong indication of disorder effects like in magnetic spin glasses. Here we provide from "1"5"1Eu-Moessbauer spectroscopy detailed information of the impact of Y"3"+ substitution on the magnetic properties of the two lattice sites, well distinguishable in the "1"5"1Eu-spectra. Since the substitution of the larger Eu"2"+ ions by the smaller Y"3"+ ions is connected with a lattice contraction, we also applied high pressure to the Eu_2PdSi_3 sample and observed drastic changes in the magnetic properties originating from a valence ...

Energy Technology Data Exchange (ETDEWEB)

The performance of the PSI/ETH focused ion beam (FIB) system has been improved to produce ion beams of very low energies down to 40 eV with a reasonable spot size of 1 {mu}m at 200 eV. (author) 2 figs., 1 ref.

Energy Technology Data Exchange (ETDEWEB)

The Large Hadron Collider (LHC), under construction at CERN, uses superconducting magnets operating at a temperature of 1.9 K to guide the circulating particles. A specific feature of the main magnets (dipoles and quadrupoles) is the two-in-one design with two magnetic channels in one common retaining structure. Indeed, the accelerator is made of two rings, mechanically linked, that have to be simultaneously aligned during the installation in the already existing LEP tunnel. The assembly tolerances of the LHC main magnets have been reconsidered to take into account the tight constraints on geometry. The dipoles are bent to follow closely the curvature of the circulating particles and to make a larger mechanical aperture available for the circulating particles. In order to minimise the geometrical errors the dipole assembly procedure is assisted by high precision survey measurements based on laser trackers. By this we hope to reduce to {+-} 1 mm the positioning ...

KoreaScience (Korea)

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... Exercises: Day and Night Classroom Exercises: Pinhole Focusing 3D Vision and Eye Health < Contact Lenses Monovision Playlist: ...

Science.gov (United States)

An experimental realization of the focusing of an atomic beam by a spontaneous radiation pressure force is reported. A simple light field configuration for focusing an atomic beam is described which is formed by four divergent Gaussian laser beams propagating along the + or - x and + or - y directions of a Cartesian coordinate system. An experimental arrangement for the laser focusing is shown, and the experimental procedure is described. The resulting atomic beam profiles are shown and discussed. It is concluded that the experiments open up the possibility of gaining control over such parameters of atomic beams as their density and divergence. 7 references.

J-STORE (Japan)

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Energy Technology Data Exchange (ETDEWEB)

Results of X-ray investigations of solid normal hydrogen are presented. Temperature dependences of the lattice parameteps, molar volumes, linear and volume expansion coefficients in the 2K-Tsub(melt) temperature range are obtaiped. An essential n-H/sub 2/ expansion anisotropy in the premelting temperature region is pointed out. It is shown that the hexagonal lattice parameter ratios over the whole investigated temperature range is considerably higher than for solid parahydrogen. A considerable difference in thermal expansion of normal hydrogen and parahydrogen in the low temperature region is revealed. It is caused by contribuation of a rotational subsystem, increasing with the temperature decrease to crystal expansion. A detailed analysis of solid n-H/sub 2/ thermodynamic properties is conducted. The data testifying to the presence of isomorphous phase transformation in the solid n-H/sub 2/ in the premelting temperature region are discussed.

International Nuclear Information System (INIS)

In this study the results of mathematical simulation and experimental research of texture transition in stress assisted shear phase transformations are discussed. The orientation distribution function (ODF) calculation model to the any type crystalline lattice symmetry materials has been suggested. By crystalline lattice symmetry analysis this computer program determines necessary amount of the initial experimental data. The experimental verification supports this model well. The ODF calculation model after shear phase transformation with equal use of all possible variants of orientation relationship or with various degrees of variant selection worked out. In this study the experimental and calculating data of the direct and reversal shear transformations #alpha# <=> #gamma# in Fe-alloys and B2 <=> B19' in Ti-Ni alloys are discussed. The stress assisted shear phase transformation model and computer program to calculate ODF after ...

Energy Technology Data Exchange (ETDEWEB)

The use of solvating polymers of polyether type is an interesting solution for the manufacturing of high capacity lithium batteries with lithium metal anodes and which can operate at T > 50 deg. C. These operating conditions are perfectly compatible with electric-powered vehicle and stationary battery applications. In order to improve the ionic conductivity of polymer electrolytes, new aprotic and amorphous polyether lattices have been synthesized having a good conductivity but also good thermal, mechanical and electrochemical stabilities. Two type of 3-D polyether lattices obtained by reticulation of linear pre-polymers have been selected as host polymers: unsaturated poly-condensate and unsaturated co-polyethers. (J.S.) 18 refs.

British Library Electronic Table of Contents (United Kingdom)

A two-dimensional (2D) lattice model with anisotropic resonant microstructures is found to provide an anisotropic band gap structure. A 2D continuum with anisotropic effective mass density is introduced to represent this lattice system. Two methods are proposed to derive the equivalent continuum. In the first method, the effective mass density of the equivalent continuum is obtained by matching the dispersion relations for harmonic waves propagating in the principal directions. The second approach employs an approximate estimation of the effective mass density by volume-averaging an effective mass that represents the resonant microstructure. For both equivalent continuum models, the effective mass density is frequency-dependent and may become negative in certain frequency ranges. Subsequen...

CERN Document Server

The main topic of this thesis concerns efficient algorithms for the calculation of determinants of the kind of matrix typically encountered in lattice QCD. In particular an efficient method for calculating the fermion determinant is described. Such a calculation is useful to illustrate the effects of light dynamical (virtual) quarks. The methods employed in this thesis are stochastic methods, based on the Lanczos algorithm, which is used for the solution of large, sparse matrix problems via a partial tridiagonalisation of the matrix. Here an implementation is explored which requires less exhaustive treatment of the matrix than previous Lanczos methods. This technique exploits the analogy between the Lanczos tridiagonalisation algorithm and Gaussian quadrature in order to calculate the fermion determinant. A technique for determining a number of the eigenvalues of the matrix is also presented. A demonstration is then given of how one can improve upon this estimate ...

International Nuclear Information System (INIS)

The EXAFS-study (Fe, Sn and Ge K-edges) of disordered by mechanical activation binary supersaturated nanocrystalline solid solutions Fe-Al, Fe-Ge, Fe-Sn and Fe-Si is presented. The EXAFS-spectra are processed by solving the inverse binary problem, using the EXAFS-spectrum of the Fe K-edge only or combining the EXAFS-spectra on two K-edges, Fe and Ge or Fe and Sn. The parameters of partial correlation functions indicate chemical short-range ordering, high local static distortions in the lattice, increasing with metalloid content. The macrostructure of other type is forming through an initial, 'local' stage within the bcc lattice.

Energy Technology Data Exchange (ETDEWEB)

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

International Nuclear Information System (INIS)

The influence of irradiation with 2.6 MeV H and He nuclei on the superconducting properties (critical temperature Tsub(c), critical current Isub(c)) of the intermetallic compound Nb_3Sn was studied. Irradiation led to a significant lowering of Tsub(c), while Isub(c) is increasing with the radiation dose. This is assumed to be due to the formation of active pinning centres in the lattice. There is a fast drop of Isub(c) after a peak value has been reached. Annealing of the samples (600-1,000"0C) led to an almost complete recovery of the initial value of Tsub(c). X-ray diffraction showed that irradiation causes considerable distortions of the lattice while the A15 crystal structure is retained. The causes of the radiation effects related to structural defects are discussed. (GSCH).

Energy Technology Data Exchange (ETDEWEB)

The physical layout of the Time-Of-Flight spectrometer at the new spallation source SINQ is presented. The concept shows up a hybrid-TOF combining a Fermi-chopper with a crystal monochromator. The demand of a versatile and flexible instrument for several applications is taken into account by the option of switching from time-focusing to monochromatic focusing mode such that the spectrometer can be optimised for both quasielastic and inelastic scattering applications. (author) 5 figs., 2 tabs., 16 refs.

International Nuclear Information System (INIS)

It is known that a high-power laser propagating through an underdense plasma can acquire a minimum spot size due to relativistic self-focusing. Beyond the focus, the nonlinear refraction starts weakening, and the spot size of the laser increases, showing periodic self-focusing/ defocusing behavior with the distance of propagation. To overcome the defocusing, we propose the introduction of a localized upward plasma density ramp. In the presence of an upward ramp of plasma density, the laser beam obtains a minimum spot size and maintains it with only a mild ripple. For suitable parameters of the laser and the plasma, we have deduced conditions for the self-focusing. This kind of plasma density ramp may be observed in a gas-jet plasma experiment and resembles a plasma lens.

Energy Technology Data Exchange (ETDEWEB)

The nucleon axial charge is calculated as a function of the pion mass in full QCD. Using domain wall valence quarks and improved staggered sea quarks, we present the first calculation with pion masses as light as 354 MeV and volumes as large as (3.5 fm)3. We show that finite volume effects are small for our volumes and that a constrained fit based on finite volume chiral perturbation theory agrees with experiment within 5% statistical errors.

Energy Technology Data Exchange (ETDEWEB)

Fuel irradiation leads to a swelling resulting from the formation of gaseous (Kr, Xe) or solid fission products which are found either in solution or as solid inclusions in the matrix. This phenomena has to be evaluated to be taken into account in fuel cladding Interaction. Fuel swelling was studied as a function of burn up by measuring the corresponding cell constant evolution by X-Ray diffraction. This study was realized on Mixed Oxide Fuels (MOX) irradiated in a Pressurized Water Reactor (PWR) at different burn-up for 3 initial Pu contents. Lattice parameter evolutions were followed as a function of burn-up for the irradiated fuel with and without an annealing thermal treatment. These experimental evolutions are compared to the theoretical evolutions calculated from the hard sphere model, using the fission product concentrations determined by the APPOLO computer code. Contribution of varying parameters influencing the unit cell value is discussed. Thermal ...

Energy Technology Data Exchange (ETDEWEB)

Time resolved phase transition and strain experiments have been performed on the millisecond time scale using a Bragg-edge transmission technique that has been developed at the Los Alamos National Laboratory. The precision with which lattice parameters can be determined from edge positions is sufficient to perform high-resolution strain measurements in uniaxial stress.

International Nuclear Information System (INIS)

The fission gas xenon bonded in bubbles, in pore, and in the lattice of mixed carbide fuels is measured by electron-probe microanalysis. Radial xenon distribution and release curves are determined and are calibrated by gas chromatography of the bonded fission gas and by burnup analysis in the respective pin sections of the irradiation experiments FR2 6A and 6C, Mol 11/K 2, and DFR 330/1. The results are correlated to the microstructure of the fuel, bonding medium, temperature, and burnup. (Auth.).

Science.gov (United States)

The (Al/sub x/Ga/sub 1-x/)/sub 0.5/In/sub 0.5/P material system, lattice matched to GaAs substrates, is useful for visible laser diodes. Here, low pressure organometallic vapor phase epitaxial growth of Ga/sub 0.5/In/sub 0.5/P and (Al/sub x/Ga/sub 1-x/)/sub 0.5/In/sub 0.5/P is examined. Epitaxial layers of bulk materials are characterized using photoluminescence, electroreflectance, Raman scattering spectroscopy, and surface morphology studies to determine lattice match and optimum growth conditions. Lattice matching at the growth temperature produces featureless growth surfaces, while lattice matching at room temperatures results in minimum photoluminescence linewidth but cracked surface due to tensile strain during growth. Raman scattering spectra of the quaternary reveal a three-mode structure, with spectral peaks due to GaP-like, in P-like, and AIP-like LO phonons. Additionally, (Al/sub x/Ga/sub ...

International Nuclear Information System (INIS)

Nuclear magnetic resonance results are presented for a number of NaCl-type compounds and cubic Laves-phase type compounds of uranium, neptunium, and plutonium. Special emphasis is placed on the Knight shift and spin-lattice relaxation time measurements and their interpretation in terms of localized or itinerant pictures of the 5f electrons. (author).

Energy Technology Data Exchange (ETDEWEB)

Generalization of the alternate directions implicit technique is used to compute the pion propagator in quenched QCD on a lattice. The full four-dimensional problem is reduced to a series of partly decoupled two-dimensional inversions. Chiral properties of the theory computed in this approach agree with those found using other methods.

International Nuclear Information System (INIS)

The compound UC_2Si_2 has been found to be ferromagnetic at low temperatures with a Curie temperature of 101"0K. The magnetization follows a Curie-Weiss law in the paramagnetic region with an effective magneton number of 2.12 Bohr magnetons per uranium atom. Partial substitution of Th atoms for the U atoms results in an expansion of the lattice, a rapid drop in the Curie temperature, and a sizable increase in the coercive field.

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The theoretical treatment of the relation between the critical angle of planar channeling and the characteristics of crystal lattice defects is carried out. The predictions are made about some typical forms of the critical angle dependence on the mean-square static displacement produced by defects, and then these predictions are detailed for the cases of homogeneous disordering, spherical clusters of point defects and dislocation loops. Analytical results are supported by the exact computer calculations for the defects in the intermetallic A-15 compounds.

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Experimental data in the Kondo lattice YbPd{sub 2}Si{sub 2} is compared with the results of a hybridization model, based ont he 'large degeneracy expansion' approximation, which takes into account the crystal field level splittings of the Yb ion. We show that satisfactory agreement is obtained with a unique set of crystal field and hybridization parameters. (orig.).

International Nuclear Information System (INIS)

The Grueneisen parameter and lattice thermal expansion of the A-15 compounds V_3Si and V_3Ge at room temperature are evaluated on the basis of the method due to Brugger and Fritz from the third order elastic constants reported earlier. The calculated values are compared with available experimental values and are found to fit satisfactorily. (author).

International Nuclear Information System (INIS)

Reduced-Moderation Water reactor (RMWR) is a light water breeder reactor developed by Japan Atomic Energy Research Institute (JAERI). The RMWR comprises tight lattice fuel assemblies with gap clearance of around 1.0 mm to reduce water volume ratio to achieve a high conversion ratio. It is important to estimate the thermal hydraulic safety margin of the tight lattice core of the RMWR. In the present study, the boiling transition (BT) prediction performance of the subchannel analysis code NASCA developed for the current BWR cores was assessed for series of tight lattice critical heat flux (CHF) experiments performed in JAERI. The test section was a 7-rod bundle with rod diameter of 12.3 mm, rod gap of 1.0 mm and heated length of 1.8m. Axial power distribution was flat. With a simple subchannel model, the code overestimates the critical power in the high mass velocity region, although the predicted critical powers in the low ...

Energy Technology Data Exchange (ETDEWEB)

Among the three modifications of calcium sulfite hemihydrate, two of them, hexagonal ..beta..-CaSO/sub 3/.1/2H/sub 2/O with a rhombohedral lattice and ..gamma..-CaSO/sub 3/.1/2H/sub 2/O with a simple triangular hexagonal lattice, were found in the authors' recent work. By heating ..cap alpha..- and/or ..gamma..-hemihydrate at 330-360/sup 0/C in a nitrogen atmosphere, the orthorhombic anhydrate ..cap alpha..-CaSO/sub 3/ was formed, with lattice constants of 6.472, 15.93, and 23.44 angstrom for a, b, and c respectively, while the body-centered tetragonal anhydrate ..beta..-CaSO/sub 3/, with lattice constants of 15.68 and 19.44 angstrom for a and c respectively, was formed by heating the ..beta..-hemihydrate. The dehydration of three hemihydrates and the hydration of two anhydrates were discussed. Calcium sulfite hemihydrate (CaSO/sub 3/.1/2H/sub 2/O) is useful as an architectural material since ...

International Nuclear Information System (INIS)

The ErNi_1_- _x Cu _x Al compounds crystallize all in the hexagonal ZrNiAl-type structure. The concentration dependence of lattice constants shows a discontinuity between x=0.5 and 0.6. This structural change has no primary impact on the magnetic order in this series, but influences the crystal field. The lower part of the crystal-field energy-level schemes has been estimated from the specific-heat data.

Energy Technology Data Exchange (ETDEWEB)

The purpose of the invention is to improve adaptability of a compression shield to irregularities of a face. This goal is achieved in that a compressible shield is made in the form of a lattice of elastic transverse plates with grooves, elastic vertical elements installed in the grooves, and an elastic plate which is concave toward the face. The plate is located vertically in the middle of the shield. The compressible shield is attached by hinges to a deflector. Telescopic cross pieces are attached by hinges to the covering section of reinforcement, offering the possibility of longitudinal movement at the point of attachment.

Science.gov (United States)

In this paper the thermal equilibrium number of solitons in DNA as a function of absolute temperature and the number of base pairs is calculated. These calculations are effected by modeling DNA as a Toda lattice with parameters chosen to match experimentally measured properties of DNA. It is found that a significant number of solitons is generated at physiological temperature. 23 refs., 2 figs.

CERN Document Server

Observations of redshift-space distortions in spectroscopic galaxy surveys offer an attractive method for measuring the build-up of cosmological structure, which depends both on the expansion rate of the Universe and our theory of gravity. Galaxies occupy dark matter halos, whose redshift space clustering has a complex dependence on bias that cannot be inferred from the behavior of matter. We identify two distinct corrections on quasilinear scales (~ 30-80 Mpc/h): the non-linear mapping between real and redshift space positions, and the non-linear suppression of power in the velocity divergence field. We model the first non-perturbatively using the scale-dependent Gaussian streaming model, which we show is accurate at the 10 (s>25) Mpc/h for the monopole (quadrupole) halo correlation functions. We use perturbation theory to predict the real space pairwise halo velocity statistics. Our fully analytic model is accurate at the 2 per cent level only on scales s > ...

Energy Technology Data Exchange (ETDEWEB)

The properties of the triplet of low-lying states in {sup 101}Mo have been studied through spectroscopy of the {gamma} radation following thermal neutron capture in {sup 100}Mo and {beta}-decay of {sup 101}Nb and through a measurement of the proton angular distributions in the {sup 100}Mo(d, p) reaction with 14 MeV deuteron energy. The half-lives of the 13.5 keV state and the 57.0 keV 5/2{sup +} state have been measured as 226(7) and 133(7) ns, respectively. These values and the quadrupole/dipole mixing ratios of the 13.5 keV and 43.5 keV transitions yield spin and parity 3/2{sup +} for the 13.5 keV level. The E2 components in the 13.5 (3/2{sup +}->1/2{sup +}) and 43.5 keV (5/2{sup +}->3/2{sup +}) transitions are {le} 8x10{sup -4} and 54(9)%, respectively. The possibility of an additional state near to the 57.0 keV level is discussed. IBFM/PTQM calculations, taking into consideration the transitional character of the {sup 100}Mo boson core, account for the ...

Energy Technology Data Exchange (ETDEWEB)

The primary E1, M1 and E2 ..gamma..-radiation in /sup 87,88,89/Sr observed after thermal neutron capture was compared with the predictions of single particle and giant resonance models. The nuclei feature a wide range of neutron binding energies between 6.3 and 11.1 MeV, which makes a 5.5 MeV spectrum of primary transition energies available for investigation. The (n, ..gamma..) reaction was used to estimate the parameters of the spin-flip M1 giant resonance in strontium. The total energy weighted M1 strength of this resonance exceeds the results of shell model and random phase approximation calculations for /sup 90/Zr by a factor of 3-4. The E1 strengths were found to agree with the established giant dipole resonance model. The few data on primary E2 transitions do not allow to differentiate between the giant quadrupole resonance and the single particle models.

International Nuclear Information System (INIS)

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

CERN Document Server

The transition region between the straight part and the ends of the coils of the LHC model and prototype dipole magnets are often identified as the origin of training quenches. In order to study how the discontinuities in the material properties of these regions affect coil pre-stress and possibly gain more insight in the quench behavior, a program was set up at CERN to analyze by 3D-FEM these particular regions. The ACCEL team, who performed a similar analysis for the main quadrupoles of the Superconducting Supercollider SSC, is entrusted with this program. In this paper we report on the results of 3D-modeling and analysis of the coil return end region, including the complete coil mass, of a 1-m single bore model magnet. This magnet represents all relevant features of the "two-in-one" LHC main dipole design concerning the winding configuration, the collar pack, the yoke, and the outer shell representing the He-vessel. The transition region between coil ends and ...

International Nuclear Information System (INIS)

We calculate parity-dependent level densities for the even-even isotopes "5"8","6"2","6"6Fe and "5"8Ni and the odd-A nuclei "5"9Ni and "6"5Fe using the shell model Monte Carlo method. We perform these calculations in the complete fp-gds shell-model space using a pairing+quadrupole residual interaction. We find that, due to pairing of identical nucleons, the low-energy spectrum is dominated by positive parity states. Although these pairs break at around the same excitation energy in all nuclei, the energy dependence of the ratio of negative-to-positive parity level densities depends strongly on the particular nucleus of interest. We find equilibration of both parities at noticeably lower excitation energies for the odd-A nuclei "5"9Ni and "6"5Fe than for the neighboring even-even nuclei "5"8Ni and "6"6Fe.

Energy Technology Data Exchange (ETDEWEB)

Laser spectroscopy measurements have been performed on neutron deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d{sup 7}6s{sup 24}F{sub 9/2} {sup {yields}} 5d{sup 7}6s6p {sup 6}F{sub 11/2} at 351.5 nm have been studied for the {sup 182-189}Ir, {sup 186}Ir{sup 1}m and {sup 191,193}Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between {sup 187}Ir and {sup 186}Ir and between {sup 186}Ir{sup 1}m and {sup 186}Ir{sup 1}g has been observed.

CERN Document Server

The main LHC superconducting magnets (dipoles and quadrupoles) use Rutherford type cables, stabilized electrically and thermally with copper profiles. The portions of cables are connected to each other by a soft soldering technique (Sn96Ag4) with an overlapping length corresponding to one pitch of the superconducting strands. The splice constitutes a "composite" structure with the interchanging layers of Sn96Ag4 and NbTi superconductor, located inside a Cu cage. In order to ensure a high level of reliability (failure probability not exceeding 10-8) for some 10000 connections in the LHC, a non-destructive technique to check the quantity of solder in the joint is foreseen. The technique is based on a gamma ray source (241Am) and the detection is position-sensitive in the transmission mode. Scintillating detectors of gamma rays are used and their accumulated length corresponds to the length of the radioactive source (120 mm). The method can be used in-situ, the ...

Energy Technology Data Exchange (ETDEWEB)

A discussion of how stress and strain affect the quantities which can be measured in an NQR experiment shows that, for stresses of the magnitude to be expected at depths up to about 10,000 feet, quadrupole coupling constants will fall in the range of 1 to 10 kHz for both the sodium and chloride ions in NaCl. The most promising system involves pulsed nuclear double resonance detection; and alterative is to observe the quadrupolar splitting of the NMR signal. Choices to be made in the measurement and mapping techniques are discussed. The well-known perturbation of the homogenous stress field in the neighborhood of a borehole is shown to be advantageous from the point of view of obtaining directional information on the stress. Construction and operation of a borehole stress sensor are considered. The NQR technique seems feasible for measuring the magnitude and direction of underground stress with a resolution of about 25 psi, or 2.5% at 1000 psi. Downhole ...

International Nuclear Information System (INIS)

Through the innovative design of a novel end plug scheme employing octopole MHD stabilization, the authors present the conceptual design of ''MINIMARS'', a small commercial fusion reactor based on the tandem mirror principle. The current baseline for MINIMARS has a net electric output of 600 MWe and they have configured the design for short construction times, factory-built modules, inherently safe blanket systems, and multiplexing in station sizes of #approx =# 600-2400 MWe. They demonstrate that the compact octopole end cell provides a number of advantages over the more conventional quadrupole (yin-yang) end cell encountered in the MARS tandem mirror reactor study, and enables ignition to be achieved with much shorter central cell lengths. Accordingly, being economic in small sizes, MINIMARS provides an attractive alternative to the more conventional larger conceptual fusion reactors encountered to date, and would contribute significantly to the lowering of ...

Energy Technology Data Exchange (ETDEWEB)

DC resistivity, dc magnetization, and specific heat of eight Sc/sub 5/Co/sub 4/Ge/sub 10/-type crystal structure compounds R/sub 5/T/sub 4/Ge/sub 10/ for R = Dy, Ho, Er, Tm, and T = Rh and Ir are presented. The resistivity, single crystal magnetization, and specific heat results show that in all those compounds, the magnetic moments order antiferromagnetically in the c direction at low temperature. However, in the Er and Tm compounds, the magnetizations along x-y hard directions do not show any anomalies above 2.0 K. This suggests that the ordered Er and Tm ions, which have positive quadrupole coefficients ..cap alpha../sub j/, interact with a crystal field that has an electronic potential valley along the c axis. The fitting of the hard axis magnetizations to Curie-Weiss law suggests that the resulting antiferromagnetic-like theta reflects the strength of the crystal field torque on the magnetic moments rather than the strength of antiferromagnetic exchange. 123 ...

International Nuclear Information System (INIS)

The level structure and configurations of "2"1"6At have been studied by observing the alpha decay of "2"2"0Fr, which is in secular equilibrium with "2"2"4Ac. Six of the 16 observed states are tentatively assigned to the configuration #pi#(h_9_/_2)"3#upsilon#(g_9_/_2)"5, and four to the mixed configuration #pi#(h_9_/_2)"3#upsilon#(g_9_/_2)"4(i_1_1_/_2)+#pi#(h_9_/_2)"2(f _7_/_2)#upsilon#(g_9_/_2)"5. These two configurations in "2"1"6At are compared with the corresponding configurations in "2"1"2Bi and "2"1"0Bi. The shape transitions are traced from the quadrupole-octupole deformed "2"2"4Ac through "2"2"0Fr and "2"1"6At, to "2"1"2Bi, described by the spherical shell model, using the alpha decay sequence beginning with "2"2"8Pa. copyright 1996 The American Physical Society.

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Isotope shift measurements have been performed for the {sup 242{ital f}}Am fission isomer with target production rates of only a few per second. The method is based on resonance ionization spectroscopy (RIS) in a buffer gas cell with radioactive decay detection of the ionization process (RADRIS). A relative isotope shift ratio X{sub {ital exp}}=IS{sup 242{ital f},241}/IS{sup 243,241}=41.7{plus_minus}0.9 has been measured for the 500.02 nm transition corresponding to a nuclear parameter A{sup 242{ital f},241}=(5.4{plus_minus}0.3) fm{sup 2}. A preliminary analysis of the quadrupole moment based on the deformed Fermi model of the nuclear charge distribution results in Q{sub 20}=35.9{plus_minus}1.1({sup +0.3}{sub {minus}0.7}) {sub model} eb. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

CERN Document Server

The 12 GeV upgrade at Jefferson Lab has identified two new large spectrometers as Physics detectors for the project. The first is a 7.5 Gev/c 35 m-sr. spectrometer that requires a pair of identical Combined Function Superconducting Magnets (CFSM) that can simultaneously produce 1.5 T dipole fields and 4.5 T/m quadrupole fields inside a warm bore of 120cm. The second is an 11 GeV/c 2 m-sr. spectrometer that requires a CFSM that simultaneously produces a dipole field of 4.0 T and a quadruple field of 3.0 T/m in a 60 cm warm bore. Magnetic designs using TOSCA 3D have been performed to realize the magnetic requirements, provide 3d fields for optics analysis and produce field and force information for the engineering feasibility of the magnets. A two-sector cos( theta )/cos(2 theta ) design with a low nominal current density, warm bore and warm iron design has been selected and analyzed. These low current densities are consistent with the limits for a cryostable ...

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Studies have been conducted to determine the feasibility of using collisional cooling for reducing emittances and energy spreads in negative-ion beams to levels commensurate with effective isobaric purification with conventional high-resolution electromagnetic isobar separators as required for use at the Holifield Radioactive Ion Beam Facility (HRIBF). We have designed a gas-filled radio frequency quadrupole ion cooler equipped with provisions for retarding energetic negative-ion beams to energies below thresholds for electron detachment at injection and for re-acceleration to initial energies after the cooling process. The device has been used to cool several ion beams with initial energy spreads, {delta}E>10 eV to final energy spreads, {delta}E{approx}2 eV FWHM, including O{sup -} and F{sup -}. Overall transmission efficiencies of {approx}14% for F{sup -} beams have been obtained. Experimental results show that electron detachment is the major loss ...

Energy Technology Data Exchange (ETDEWEB)

This work is based on the study of cesium ({sup 118,146}Cs) and francium ({sup 207-213}Fr,{sup 220-228}Fr) isotopes by hyperfine atomic spectroscopy and on the interpretation of these results from the nuclear physics point of view. The measured nuclear quantities are: the spin, the magnetic moment, the electric quadrupole moment and the mean square charge radius. The experimental method which is based on hyperfine optical pumping with a tunable laser, followed by magnetic analysis of the atoms is described in the first part. Results related to atomic physics are also presented. In the second part, these data are interpreted in the framework of nuclear models. The deformation of light cesium isomers are compared to values obtained from a theoretical self-consistent calculation. Heavy francium isotopes are situated in an area where the existence of static octupole deformations have been predicted. The odd-even staggering measured on the mean square radius is abnormal ...

International Nuclear Information System (INIS)

Ammonia adsorption on the external surface of C_3_0B_1_5N_1_5 heterofullerene was studied using density functional calculations. Three models of the ammonia-attached C_3_0B_1_5N_1_5 together with the perfect model were optimized at the B3LYP/6-31G"* level. The optimization process reveals that dramatic influences occurred for the geometrical structure of C_3_0B_1_5N_1_5 after ammonia adsorption; the B atom relaxes outwardly and consequently the heterofullerene distorts from the spherical form in the adsorption sites. The chemical shielding (CS) tensors and nuclear quadrupole coupling constants of B and N nuclei were calculated at the B3LYP/6-311G"*"* level. Our calculations reveal that the B atom is chemically bonded to NH_3 molecule. The B atom in the NH_3-attached form has the largest chemical shielding isotropic (CSI) value among the other boron nuclei. The C_Q parameters of B nuclei at the interaction sites are significantly decreased after ammonia adsorption.

International Nuclear Information System (INIS)

It has been predicted for several years that light is focused (optically guided) as well as amplified by the electron beam in a free electron laser (FEL). The degree of focusing depends strongly on both electron beam and optical beam characteristics. In an FEL oscillator the degree of focusing varies with intracavity optical power during the macropulse. We report the first direct measurements of the evolution of transverse optical model size and shape between small signal and saturation in a short wavelength (Compton regime) FEL oscillator. The mode measurements on the Mark III FEL oscillator are shown to be consistent with theory, requiring both refractive and gain contributions to guiding. (orig.).

UK PubMed Central (United Kingdom)

BackgroundMost reports of scientific misconduct have been focused on principal investigators and other scientists (e.g., biostatisticians) involved in the research...Full Text Available

UK PubMed Central (United Kingdom)

This paper focuses on the Internet as a tool for enhancing behavior and lifestyle changes to reduce the burden of cancer at a population level. The premise of this paper is that the Internet...Full Text Available

UK PubMed Central (United Kingdom)

OBJECTIVEEvaluate the qualitative and quantitative differences between moderated and unmoderated on-line social support groups focused on asthma.DESIGNA...Full Text Available

Science.gov (United States)

... In this paper we review the recent results concerning physical aspects of QWlP and QDIP operation focusing primarily on the electron transport ...

UK PubMed Central (United Kingdom)

Two-way communication between the conceptus and the mother during early pregnancy is essential if the pregnancy is to survive. In this review, our primary focus is on biochemical communication...Full Text Available

UK PubMed Central (United Kingdom)

Nativist and constructivist approaches to the study of development share a common emphasis on characterizing beginning and end states in development. This focus has highlighted the question...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

An array of sonic transducers, useful for medical ultrasonic imaging, has individual sections thereof separately coupled for forming separate beams of sonic energy which converge, respectively, to separate foci along a common axis of the beams. The ratio of the diameter of the radiating aperture of the array relative to a wavelength of the sonic energy is chosen to provide a moderate degree of focusing so that the depth of field at one focus blends with the depth of field of the next focus. Thereby, there is formed a continuous region of substantially uniform intensity of sonic radiation along the common beam axis. Circuitry is provided for selecting one or more specific foci dependent on the bounds of a selected region to be insonified. Upon reception of sonic energy, circuitry is provided for selecting one or more specific foci as a function of the time of travel of an echo from a subject being observed to approximate a ...

International Nuclear Information System (INIS)

The activities and the policy in the Netherlands regarding the development of the title systems since 1990 are briefly outlined, focusing on the use of PV-systems in buildings. 5 figs., 1 tab.

UK PubMed Central (United Kingdom)

It is one of the central aims of the philosophy of science to elucidate the meanings of scientific terms and also to think critically about their application. The focus of this essay is the scientific...Full Text Available

UK PubMed Central (United Kingdom)

The paper describes advances in statistical methods for prevention research with a particular focus on substance abuse prevention. Standard analysis methods are extended to the typical research...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

An important component of the overall program to validate WIMS-AECL for use with RFSP in the analysis of CANDU-6 reactors for design and safety analysis calculations is the validation of calculations of incremental cross sections used to represent reactivity devices. A method has been developed for the calculation of the three-dimensional neutron flux distribution in and around CANDU reactor fuel channels and reactivity control devices. The methods is based on one- and two dimensional transport calculations with the WIMS-AECL lattice cell code, SPH homogenization, and three-dimensional flux calculations with finite-difference diffusion theory using the MULTICELL code. Simulations of Wolsung 1 Phase-B commissioning measurements and Point Lepreau restart tests have been performed, as a part of the program to validate WIMS-AECL lattice cell calculations for application to CANDU reactor simulations in RFSP. The incremental cross section properties ...

International Nuclear Information System (INIS)

Three new rare earth metal-rich compounds, Gd_6MTe_2 (M=Co, Ni) and Er_6RuTe_2, were synthesized in direct reactions between the R, R_3M, and R_2Te_3 (R=Gd, Er, M=Co, Ni, Ru). These materials all adopt the same Zr_6CoAl_2 structure type with space group P6-bar 2m (No. 189, Z=1). Single crystal structures of Gd_6CoTe_2 and Er_6RuTe_2 were determined and lattice parameters are a=b=8.3799(5), c=3.9801(4) A, and a=b=8.1473(5) A, c=3.9962(4) A, respectively. Gd_6NiTe_2 was characterized by X-ray powder diffraction; lattice parameters are a=b=8.412(2), c=3.9577(9) A. Metal-metal bonding correlations were analyzed using the empirical Pauling bond order concept.

International Nuclear Information System (INIS)

Electron spin polarization in excess of 70% has been observed in photoemission from a 0.1 #mu#m-thick epitaxial layer of In_xGa_1_-_xAs with x #approx# 0.13 grown on a GaAs substrate. Under these conditions, the epitaxial layer is expected to be highly strained by the 0.9% lattice mismatch, as confirmed by x-ray diffractometer measurements of the lattice parameter. The electron polarization and the quantum efficiency have been measured as a function of the excitation photon energy from 1.25 to 2.0 eV. A significant enhancement of the electron polarization occurs in the vicinity of 1.33 eV where the expected strain-induced level splitting permits optical excitation of a single band transition. Measurements made on a control sample of 1.14 #mu#m thickness, significantly larger than the critical thickness for pseudomorphic strain, show no polarization enhancement. These measurements represent the first observation of strain-enhanced electron spin ...

International Nuclear Information System (INIS)

The temperature dependence of T_1 spin-lattice relaxation time on "5"1V, "6"9Ga, "7"1Ga and Knight shift on "5"1V and "2"9Si nuclei in polycrystalline V_3Si, V_3Ga, V_3Ge and in the monocrystal V_3Si in normal state is investigated. For V_3Si and V_3Ga a rapid growth (T_1T)"-"1 is observed with temperature decrease while for V_3Ge the maximum (T_1T)"-"1 at T approximately equal to 60 K has been found. The temperature dependence peculiarities have been discussed on the basis of theoretical models available and zone structure calculations for A-15 compounds. The T_1 anisotropy and possibility of its experimental discovery are considered. Anisotropic contribution in (T_1T)"-"1 and contributions of d states of different symmetries into the electron state density at the Fermi level are estimated for V_3Si from T_1 measurements.

CERN Document Server

We point out that electromagnetic one-way edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D gyroelectric photonic crystals possessing Dirac point-derived bandgaps, can appear in more general settings. In particular, we show that the TM modes in a gyromagnetic photonic crystal can be formally mapped to electronic wavefunctions in a periodic electromagnetic field, so that the only requirement for the existence of one-way edge modes is that the Chern number for all bands below a gap is non-zero. In a square-lattice gyromagnetic Yttrium-Iron-Garnet photonic crystal operating at microwave frequencies, which lacks Dirac points, time-reversal breaking is strong enough that the effect should be easily observable. For realistic material parameters, the edge modes occupy a 10% band gap. Numerical simulations of a one-way waveguide incorporating this crystal show 100% transmission across strong defects, such as perfect ...

International Nuclear Information System (INIS)

Lithium ammonium sulfate (LAS) undergoes a phase transition at Tsub(c1) = 459.5deg K from a paraelectric phase (phase 1) to a ferroelectric phase (phase II) and again at Tsub(c2) = 283deg K to a polar ferroelastic phase (phase III). Proton spin lattice relaxation investigations in the temperature range 480-77deg K at 10 MHz show discontinuous changes in Tsub(1) at the transition temperatures, indicating first order phase transitions. The absence of the slow motion region (#omega#sub(not)tausub(not)>>1) shows that the ammonium ions are reorienting fast enough to keep the resonance absorption line narrow down to liquid nitrogen temperatures. The possibility of a second minimum and a low activation energy, Esub(a) = 2.659 kcal/mole, in phase III suggest the possibility of tunnelling of the protons at low temperatures. The nature of the transitions have been discussed in the light of the available literature. The unusually high activation energy, Esub(a) = 17.845 ...

Energy Technology Data Exchange (ETDEWEB)

Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer electrolytes has the same performances as ...

Science.gov (United States)

A film of GaSb grown epitaxially on a Si substrate is a direct transition semiconductor useful for application as a light source in Si photonics and channel material in next-generation field effect transistors because its energy bandgap is close to the optical fibre communication wavelength and it possesses high carrier mobility. Here, we report a novel method for heteroepitaxial growth of high-quality GaSb/Si films, despite having a lattice mismatch as large as ? 12%, using elastically strain-relaxed GaSb nanodots with ultrahigh density as seed crystals for film growth. The nanodot seed crystals were grown epitaxially by restricted contact with the Si substrate through nanowindows in an ultrathin SiO(2) film on the Si substrate. A light-emitting diode containing GaSb/Si films with a thickness of ? 90 nm fabricated by this method operated at room temperature. The growth method was also used to fabricate AlGaSb films of high quality. Our method provides a new avenue ...

International Nuclear Information System (INIS)

Local-density-functional calculations of the energy bands, equilibrium lattice constant, bulk modulus, and cohesive energy have been performed using a newly developed self-consistent full-potential linearized augmented-plane-wave (LAPW) program. Scalar-relativistic effects are included for the band states, and the core-level states are treated fully relativistically in a central-field approximation. Excellent agreement is obtained with the experimental lattice constant and bulk modulus. Generally good agreement is obtained with the scalar-relativistic pseudopotential results of Bylander and Kleinman. In this context, the impact of various approximations used in including the core states is assessed, and these findings are related to the frozen-core and pseudopotential approximations, especially with regard to the treatment of the somewhat overlapping 5p semicore states and their effect on ground-state properties. Comparison with the recent LAPW ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a study on the crystallization and growth mechanism of selenium nanowires induced by silver nanoparticles at ambient conditions with special reference to the effects of factors such as the shapes and size of silver nanoparticles, the induced reaction time, and the molar ratio of Ag{sup 0} to SeO{sub 3}{sup 2-} ions. The synthesis approach is conducted with no need of any stabilizers, and with no sonochemical process and/or templates. It is found that whether silver spherical particles or colloids can lead to the formation of nanowires with average diameter of 25 nm and lengths up to a few micrometers, and silver nanoplates lead to the formation of flat Se nanostructures. In particular, Au, Cu, Pt, and Pd particles cannot induce the growth of selenium nanowires in aqueous solution at room temperature. The results indicate that silver particles play a critical role in determining the growth of selenium nanowires. The lattice match between ...

International Nuclear Information System (INIS)

We report a detailed augmented-plane-wave energy-band study and wave-function analysis of stoichiometric PdH which shows that, even though the Fermi surface of PdH is qualitatively similar to that of silver, the simple ''proton model'' is not valid. Instead, the screening of the proton in PdH is found to be larger than in an isolated H atom due, in part, to the formation of a H-Pd bonding band below the bottom of the d-band complex. This result, which is in qualitative agreement with Switendick's earlier calculation, is confirmed by ultraviolet photoemission experiments. A partial density-of-states (DOS) analysis in the energy range spanned by the six valence and conduction bands reveals the quantitative details of the bonding mechanism between the Pd and H constituents. At the Fermi energy, the high Pd d to H s DOS ratio approx. 10.3 is found to be far higher than expected in silver, despite the fact that the Fermi-surface geometry is similar. The field-induced conduction-electron ...

International Nuclear Information System (INIS)

In support of Stockpile Stewardship activities, accelerated aging tests on a plutonium alloy enriched with 7.3 at.% of "2"3"8Pu is underway using dilatometry at 35, 50, and 65 deg. C and immersion density measurements of materials stored at 50 deg. C. Changes in density are expected from radiation damage in the lattice and helium in-growth. After 25 equivalent years of aging, the dilatometry data shows that the alloys at 35 deg. C have expanded in volume by 0.11-0.12% and have started to exhibit a near linear expansion behavior primarily caused by the helium accumulation. The average He-to-vacancy ratio from tested specimens was determined to be around 2.55. The model for the lattice damage and helium in-growth accurately represents the volume swelling at 35 deg. C. The density converted from the dilatometry corresponds well to the decreasing density trend of reference plutonium alloys as a function of time.

International Nuclear Information System (INIS)

A method that employs simultaneous neutron and #gamma#-ray diffraction techniques is proposed for accurate measurements of strains with or without an applied electric field (0-100 kV m"-"1). Instead of an absolute determination of the position of the neutron Bragg peak, a relative measurement of the neutron and #gamma# peak positions is used and allows a determination of the lattice-parameter changes with an accuracy of within 2 x 10"-"6. This technique avoids systematic errors originating in sample rotations by taking advantage of a reference directly related to the crystal lattice. The method appears to be particularly important for crystals that exhibit structural phase transitions, as demonstrated by the measurement of the strain U_x_x in KH_2PO_4 crystals as a function of temperature and applied electric field. In this case the errors would amount to #+-#20%. The results demonstrate the need to re-examine the theory previously proposed by ...

Science.gov (United States)

The nature of extralattice aluminum and its effect on acidity in zeolites was studied. A series of zeolites (some commercial), dealuminated by various methods, were obtained having Si/Al ratios between 1.5 and 20. These were characterized using volumetric sorption, XRD, AA, NMR, and reaction studies. Samples dealuminated using ammonium hexafluorosilicate were found to contain little or no extralattice aluminum. In contrast, steam-dealuminated zeolites had large amounts of extralattice aluminum. In some cases a significant portion of the extralattice aluminum was unobservable by [sup 27]Al NMR, suggesting the existence of an aluminum species of low symmetry. Proton NMR indicated that all the protons were associated with the lattice aluminum atoms. Depending on the preparation history, different groups of H-Y zeolites exhibited different maxima in catalytic activity as a function of aluminum content. The maxima in catalytic activity for n-pentane cracking was found ...

International Nuclear Information System (INIS)

Using an ab initio pseudopotential method within a generalized gradient approximation of the density functional theory, the structural, electronic, and phonon properties of SrS in the B1 (NaCl) and B2 (CsCl) structures have been studied. The calculated lattice constants, static bulk modulus, and first-order pressure derivative of the bulk modulus are reported for both the B1 and B2 structures and compared with previous experimental and theoretical calculations. Electronic band structures and densities of states have been derived for SrS. Subsequently, a linear-response approach to the density functional theory is used to derive the phonon frequencies and densities of states.

Energy Technology Data Exchange (ETDEWEB)

We summarize our lattice QCD study of the form factor at zero recoil in the decay {bar B} {yields} D*{ell}{bar {nu}}. After careful consideration of all sources of systematic uncertainty, we find, h{sub A{sub 1}}(1) = 0.913{sub -17-30}{sup +24+17}, where the first uncertainty is from statistics and fitting while the second combined uncertainty is from all other systematic effects.

CERN Document Server

Hydroxyapatite samples were produced by two different wet-chemical methods, and characterized by x-ray diffraction, infrared and compression strength measurements. The x-ray diffraction measurements were simulated using the Rietveld method, and structural data as lattice parameters and average crystallite size were obtained. The infrared spectra showed the presence of CO$_3^{2-}$ ions in all samples, indicating a contamination by these ions. By mixing samples produced by both methods, a bioceramic was obtained and, after sintering, samples with very high compression strengths (26--30 MPa) were obtained.

International Nuclear Information System (INIS)

The principle of conservation and transferability of chemical bonds explains the recent discovery by extended x-ray absorption fine-structure measurements of two unequal anion-cation bond lengths R/sub A/C and R/sub B/C in A/sub x/B/sub 1-x/C zinc-blende semiconductor alloys despite the close adherence of the lattice constant to the average value (Vegard rule). This bond alternation, manifested as a structural distortion to a local chalcopyrite coordination around the anions, explains also most of the observed optical bowing in semiconductor alloys.

Energy Technology Data Exchange (ETDEWEB)

Metallic multilayers offer a fantastic playground to investigate elastic stresses in films of nanometer thickness. We will present and discuss a few examples from our recent work on Au-Ni and Ag-Cu systems where we combined plate bending measurements and electron or X-ray diffraction to investigate stress buildup and interfacial mixing. Comparing these two cases we discuss the results with respect to basic parameters like the misfits in lattice parameters and in elastic moduli, the mixing enthalpies and the surface energies.

Energy Technology Data Exchange (ETDEWEB)

The CeO{sub 2}-ZrO{sub 2}-Bi{sub 2}O{sub 3} samples with different bismuth content were prepared in this study. By the doping of Bi{sub 2}O{sub 3} into the lattice, TPR profiles of the CeO{sub 2}-ZrO{sub 2} shifted to lower temperatures and oxygen storage capacity increased remarkably. It is concluded that the reason for such a behavior is probably due to both the formation of oxygen vacancies which enhance the oxygen mobility and the simultaneous reduction of Ce{sup 4+} and Bi{sup 3+} in the mixed oxides. (authors)

International Nuclear Information System (INIS)

We demonstrate reversible movement of (1/2)[110](110) dislocation loops generated from nanodisturbances in a #beta#-titanium alloy. High resolution transmission electron microscope observations during an in situ tensile test found three reversible deformation mechanisms, nanodisturbances, dislocation loops and martensitic transformation, that are triggered in turn with increasing applied stress. All three mechanisms contribute to the nonlinear elasticity of the alloy. The experiments also revealed the evolution of the dislocation loops to disclination dipoles that cause severe local lattice rotations.

CERN Document Server

The study of randomness in low-dimensional quantum antiferromagnets is at the forefront of research in the field of strongly correlated electron systems, yet there have been relatively few experimental model systems. Complementary neutron scattering and numerical experiments demonstrate that the spin-diluted Heisenberg antiferromagnet La2Cu(1-z)(Zn,Mg)zO4 is an excellent model material for square-lattice site percolation in the extreme quantum limit of spin one-half. Measurements of the ordered moment and spin correlations provide important quantitative information for tests of theories for this complex quantum-impurity problem.

International Nuclear Information System (INIS)

An annealing with the nanosecond laser light pulse is applied for crystal lattice reconstruction of a disturbed near-surface layer, which was created in semiconductor material as a result of the implantation process. Radiation with energy density higher than the threshold value causes the melting of the surface layer and than the epitaxial recrystallization from the melt on a different substrate. Structural changes occurring in the Ge implanted Si crystals after annealing with different energy densities are investigated by means of the cross-section high-resolution transmission electron microscopy. (author)

British Library Electronic Table of Contents (United Kingdom)

We have successfully grown single crystalline Formula Not Shown with the range of Formula Not Shown using the floating-zone method. All compounds show orthorhombic symmetry in this substitution range, but the difference between lattice constants a and b decreases with increasing Sr concentration and becomes almost zero at Formula Not Shown . Characteristic temperatures, which correspond to antiferromagnetic ordering and structural transition, decrease with increasing Sr concentration. The value of the magnetic susceptibility below 30K increases with increasing Sr concentration. The temperature dependence of the electrical resistivity revealed that Sr substitution significantly suppresses the highly anisotropic electric structure of Formula Not Shown .

International Nuclear Information System (INIS)

In this work, we investigate the interstitial injection into the silicon lattice due to high-dose, low-energy arsenic implantation. The approach consists in monitoring the diffusion of the arsenic profile as well as of the boron profile in buried #delta#-doped layers, when amounts of the as-implanted arsenic profile are removed by low-temperature wet silicon etching. The experimental results indicate that the contribution of the implantation damage to the transient enhanced diffusion of boron, and thus the interstitial injection, is not the main one. On the contrary, interstitial generation due to arsenic clustering seems to be more important for the present conditions.

International Nuclear Information System (INIS)

This study aims to investigate the difference in the interaction of antimicrobial peptides with two classes of zwitterionic peptides, phosphatidylethanolamines (PE) and phosphatidylcholines (PC). Further experiments were performed on model membranes prepared from specific bacterial lipids, lipopolysaccharides (LPS) isolated from Salmonella minnesota. The structure of the lipid-peptide aqueous dispersions was studied by small-and wide-angle X-ray diffraction during heating and cooling from 5 to 85 C. The lipids and peptides were mixed at lipid-to-peptide ratios 10-10000 (POPE and POPC) or 2-50 (LPS). All experiments were performed at synchrotron soft condensed matter beamline A2 in Hasylab at Desy in Hamburg, Germany. The phases were identified and the lattice parameters were calculated. Alamethicin and melittin interact in similar ways with the lipids. Pure POPC forms only lamellar phases. POPE forms lamellar phases at low temperatures that upon heating transform ...

CERN Document Server

We study the production of gravitational waves from cosmic domain walls created during phase transition in the early universe. We investigate the process of formation and evolution of domain walls by running three dimensional lattice simulations. If we introduce an approximate discrete symmetry, walls become metastable and finally disappear. We calculate the spectrum of gravitational waves produced by collapsing metastable domain walls. Extrapolating the numerical results, we find the signal of gravitational waves produced by domain walls whose energy scale is around 10^10-10^12GeV will be observable in the next generation gravitational wave interferometers.

International Nuclear Information System (INIS)

A theoretical study of structural and electronic properties of GeC, SnC and GeSn is presented using the full potential linearized augmented plane wave method. In this approach, the generalized gradient approximation was used for the exchange-correlation potential. Results are given for lattice constant, bulk modulus and its pressure derivative in both zinc-blende and rocksalt structures. Band structure, density of states and band gap pressure coefficients in zinc-blende structure are also given. The results are compared with previous calculations and with experimental measurements.

Energy Technology Data Exchange (ETDEWEB)

The orbit response matrix (ORM) method [1] is applied to model the Fermilab Booster with parameters such as the BPM gains and rolls, and parameters in the lattice model, including the gradient errors and magnets rolls. We found that the gradients and rolls of the adjacent combined-function magnets were deeply correlated, preventing full determination of the model parameters. Suitable constraints of the parameters were introduced to guarantee an unique, equivalent solution. Simulations show that such solution preserves proper combinations of the adjacent parameters. The result shows that the gradient errors of combined-function magnets are within design limits.

Energy Technology Data Exchange (ETDEWEB)

We consider the radiation of particles (electrons and positrons) undergoing planar channeling in a single crystal of small thickness L. We show that for Lapprox...pi..b/theta/sub L/, where b is the lattice constant and theta/sub L/ is the Lindhard angle, in addition to the principal maxima of spontaneous radiation of channeled particles in the spectrum there are additional interference maxima, and the positions of all maxima of the radiation intensity depend on L. We discuss the dependence of the intensity of radiation at various frequencies on the crystal thickness.

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Power supply ripple at frequencies of 720 Hz and its harmonies is expected to affect the motion of particles in the collider. These ripple frequencies are nearly resonant with the betatron frequencies. To estimate the tolerable ripple levels, we have tracked particles through the complete nonlinear lattice for 10{sup 4} turns with ripple fed from 10 different power stations and including up to 7 different ripple frequencies. We presently estimate that relative ripple amplitudes must be below the 10{sup 8} level for there to be no significant impact on the emittance over the short term.

CERN Document Server

Using the finite-range regularisation (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyse the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement ~1% with the experimental value of M_rho from the former approach. These results are extended to the case of the nucleon mass.

Energy Technology Data Exchange (ETDEWEB)

The magnetic and electronic properties of non-Fermi liquid UCu{sub 4Pd} depend on annealing conditions. Local structural changes due to this annealing are reported from UL{sub III}- and Pd K-edge x-ray absorption fine-structure measurements. In particular, annealing decreases the fraction of Pd atoms on nominally Cu 16e sites and the U-Cu pair-distance distribution width. This study provides quantitative information on the amount of disorder in UCu{sub 4Pd} and allows an assessment of its possible importance to the observed non-Fermi liquid behavior.

CERN Document Server

We study a percolation process on the planted binary tree, where clusters freeze as soon as they become larger than some fixed parameter N. We show that as N goes to infinity, the process converges in some sense to the frozen percolation process introduced by Aldous. In particular, our results show that the asymptotic behaviour differs substantially from that on the square lattice, on which a similar process has been studied recently by van den Berg, de Lima and Nolin.

International Nuclear Information System (INIS)

Supplemental criticality safety analysis of a pool type storage for TRIGA spent fuel at 'Jozef Stefan' Institute in Ljubljana, Slovenia, is presented. Previous results (Ravnik, M, Glumac, B., 1996) have shown that subcriticality is not guaranteed for some postulated accidents. To mitigate this deficiency, a study was made about replacing a certain number of fuel elements in the rack with absorber rods (Glumac, B., Ravnik, M., Logar, M., 1997) to lower the supercriticality probability, when the pitch is decreased to contact (as a consequence of a severe earthquake) in a square arrangement. The criticality analysis for the hexagonal contact pitch is presented in this paper, following the same scenario as outlined above. The Monte Carlo computer code MCNP4B with ENDF-B/VI library and detailed three dimensional geometry was used. First, the analysis about the influence of the number of triangular fuel piles on the bottom that could appear, if the fuel rack, made of three segments, ...

International Nuclear Information System (INIS)

The crystal structure, lattice strain due to the antiferromagnetic ordering, and magnetic form factor in the itinerant 5f compounds UTGa_5 (T=Ni, Pd, Pt) have been studied by neutron scattering. High-resolution powder diffraction revealed that the tetragonality of the U-Ga layers increases down to the series of the transition metal element T. The integrated intensities of the antiferromagnetic reflections can be well explained with the Neel-type structure for UNiGa_5, whereas UPtGa_5 has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the c plane. In both compounds the uranium moments orient along the c axis with moments of 0.75(5) and 0.32(5) #mu#_B for UNiGa_5 and UPtGa_5, respectively. No magnetic peak could be observed in the powder diffraction pattern of UPdGa_5 due to the small magnetic moment less than the experimental sensitivity. The orbital contributions in the magnetic form factor are reduced from the free-ion value, ...

Energy Technology Data Exchange (ETDEWEB)

X-ray magnetic diffraction (XMD) technique was applied to an orbital ordering compound of ferromagnetic YTiO{sub 3} for the first time. The orbital-magnetic form factor {mu} {sub L}(k) and the spin-magnetic form factor {mu} {sub S}(k) were independently measured by utilizing the LS separation ability of the XMD. The {mu} {sub L}(k) was measured for ten reciprocal-lattice points. No significant values of the {mu} {sub L}(k) were observed for most of the reciprocal-lattice points within the estimated statistical errors, which suggested quenching of the orbital moment. The {mu} {sub S}(k) was measured for 22 reciprocal-lattice points. Fourier synthesis of the {mu} {sub S}(k) gave the spin density distribution m {sub S}(r) in the real space. The obtained m {sub S}(r) map shows the characteristic feature of the electron distribution of 3d electron in the t{sub 2g} state of a Ti atom coordinated by O{sup 2-} ions, in which the ...

International Nuclear Information System (INIS)

The quenched chiral logarithms are examined on a 163x28 lattice with Iwasaki gauge action and overlap fermions. The pion decay constant fpi is used to set the lattice spacing, a = 0.200(3) fm. With pion mass as low as #approx#180 MeV, we see the quenched chiral logarithms clearly in mpi2/m and fP, the pseudoscalar decay constant. The authors analyze the data to determine how low the pion mass needs to be in order for the quenched one-loop chiral perturbation theory (chiPT) to apply. With the constrained curve-fitting method, they are able to extract the quenched chiral logarithmic parameter delta together with other low-energy parameters. Only for mpi<=300 MeV do we obtain a consistent and stable fit with a constant delta which they determine to be 0.24(3)(4) (at the chiral scale Lambdachi = 0.8 GeV). By comparing to the 123x28 lattice, they estimate the finite volume effect to be about 2.7% for the smallest pion mass. ...

Energy Technology Data Exchange (ETDEWEB)

Focused ion beam (FIB) systems prove to be useful precision micromachining tools for a wide variety of applications. This micromachining technique includes scanning ion microscopy (SIM), micromachining by physical sputtering, and the ion-beam induced surface chemistry for etching and deposition. This technique is applied to image and modify IC's, to micromechanical applications, to modify the tip shape of tungsten emitters, and to prepare cross sections of selected regions for inspection in a transmission electron microscope (TEM). (orig.)

Energy Technology Data Exchange (ETDEWEB)

Ti honeycombs with the side of 800 and 400 nm were fabricated by focused ion beam (FIB), though the surfaces of the bottom and wall of the Ti honeycombs were rough, as compared with the surfaces of the bottom and wall of the Si honeycomb. It is demonstrated that the nanoscale Ti components can be fabricated in a short time by FIB.

International Nuclear Information System (INIS)

A general expression for the current-density distribution of a focused-ion beam (FIB) in the chromatic-aberration region is set up in the form of a definite integral. With the experimentally obtained ion-energy distribution of a liquid-metal ion source, its contribution to the FIB current-density distribution is estimated. Calculated results explain the wide-exponential tail of a FIB.

Energy Technology Data Exchange (ETDEWEB)

This work provides an overview of existing plants in Europe and describes the substrates being used. It focuses on the individual farm-scale and community plants, as these are the two main types now being built. It also describes plants currently under construction, especially in Germany and Denmark, where the major efforts are focused. A description of how the technique has developed over the past few years, its current state of development, the motivation and economic balance, and the substrate characteristics, is presented.

Energy Technology Data Exchange (ETDEWEB)

We have researched several new focused ion beam (FIB) micro-fabrication techniques that offer control of feature shape and the ability to accurately define features onto nonplanar substrates. These FIB-based processes are considered useful for prototyping, reverse engineering, and small-lot manufacturing. Ion beam-based techniques have been developed for defining features in miniature, nonplanar substrates. We demonstrate helices in cylindrical substrates having diameters from 100 {micro}m to 3 mm. Ion beam lathe processes sputter-define 10-{micro}m wide features in cylindrical substrates and tubes. For larger substrates, we combine focused ion beam milling with ultra-precision lathe turning techniques to accurately define 25-100 {micro}m features over many meters of path length. In several cases, we combine the feature defining capability of focused ion beam bombardment with additive techniques such as evaporation, sputter ...

Energy Technology Data Exchange (ETDEWEB)

The minimization of the environmental footprint is the underlying principle of companies involved in sustainable development. At the same time, those companies seek to contribute to the economic and social development of the communities in which they have a presence. The evidence linking sustainable development and value creation are examined in this report targeted to the investment community, which is part of an overall leadership initiative undertaken by the Conference Board of Canada. The benchmarks of companies committed to sustainable development have, on the whole, been matched or exceeded, as shown by recent evidence based on the performance of seven prominent funds and indices managed in Canada, the United States, and western Europe. They are: the Domini Social Equity Fund (American focus), the EcoValue 21{sup TM} (American focus), the Dow Jones Sustainability Group Index (international focus), Storebrand Scudder ...

Energy Technology Data Exchange (ETDEWEB)

A method has been developed to optimize the energy resolution of a horizontally focusing monochromator. The method consists of determining the optimum radius of curvature of the cylindrically bent monochromator crystal by minimizing the total diffracted X-ray flux measured through an X-ray absorption foil. When measured at an absorption edge a global minimum can be identified, which corresponds to the minimum energy band accepted along the entire length of the crystal. Experimental verification of this method has been validated by comparing X-ray fluorescent scans taken for a series of crystal curvatures and by directly measuring the X-ray beam profiles at the corresponding points. The actual optical configuration and asymmetric-cut parameter of the focusing monochromator on beamline X4C at the National Synchrotron Light Source are modeled and ray tracing simulations of the optical system are compared with direct beam profile measurements.