bluuebunny/crossref_metadata_2025 huggingface dataset:
Early intervention in the general practice setting
Authors: McLean Neil J.
Published: July 2007

Abstract: There is a growing pressure on general practitioners to become more involved in the detection and management of alcohol related problems. However, there is evidence to suggest that general practitioners are unaware of the alcohol consumption of many of their patients, and even when they are aware that their patients are drinking too much, they are reluctant to manage these problems. This paper discusses some of the reasons why general practitioners avoid dealing with their heavy drinking patients. It is argued that advising patients to modify their alcohol consumption should be viewed as an exercise in health promotion, analogous to advising them to stop smoking or lose weight. The disease model of alcoholism, which is adhered to by many general practitioners, is seen as an impediment to the effective management of heavy drinkers within general practice.
The contribution of blood alcohol concentration formulae to establishing a responsible drinking level for females
Authors: Blaze‐Temple Debra , Binns Colin W. , Somerford Peter J.
Published: July 2007

Abstract: The use of formulae for calculating blood alcohol concentration (BAC) supports the recent NHMRC drinking guidelines in the establishment of a daily limit of up to 2 drinks female/4 drinks male as opposed to a 3 drink female/4 drink male ratio. BAC formulae have other educational uses as well, such as information related to alcohol consumption and drink driving BAC limits. Public health professionals are still not able to answer questions about the health damage associated with certain types of drinking patterns (number of days, length of drinking session) because of the lack of applicable research.
On the Intrinsic Anisotropy in Neutron Depolarization in Presence of a Magnetic Field
Authors: Grigoriev S.V. , Kraan W.H. , Maleyev S.V. , Okorokov A.I. , Rekveldt M.TH. , Runov W.
Published: July 2007

The theoretical solution of the problem of neutron depolarization in magnetic materials with the presence of magnetic field is presented. The particular case, when an applied magnetic field is perpendicular to the neutron velocity, is considered. The solution shows clearly the essential role of intrinsic depolarization anisotropy with respect to neutron velocity as well as an anisotropy produced by magnetic field in a magnetic medium. The theoretical results are confirmed in experiments for the first time.
A Study on the Calibration of a Time-focused Inelastic Neutron Scattering Spectrometer
Authors: Albertini V. Rossi , Colognesi D. , Tomkinson J.
Published: July 2007

The calibration of a time-focused spectrometer for the analysis of inelastically back-scattered neutrons is discussed. By comparison with a reference spectrum, a non linear system of the kinetic equations for neutrons is obtained and the calibration process is outlined. This provides a deeper understanding of the question of expected inaccuracies on the measured spectra. In particular, the effect on the parameters of a possible misassignment of the reference spectrum features is examined in detail. A suitable molecular crystal (2,5 diiodothiophene) is identified as the recommended calibrant. Using different transitions from the spectrum of this calibrant the inaccuracies introduced by misassignment are assessed.
Experimental Evaluation of Neutron Spectra in the Irradiation Fields of a Typical Material Test Research Reactor
Authors: Malkawi S.R. , Ahmad N.
Published: July 2007

Neutron energy spectra at different regions inside and around the core of Pakistan Research Reactor-1 (PARR-1), a typical swimming pool type material test research reactor, have been evaluated. The method of multiple foil activation was used together with the adjustment codes MSITER and SANDBP to determine the experimentally measured spectra. The pre-information required by the adjustment codes was obtained through modeling the core and its surroundings in three-dimensions and the use of the transport code WIMS-D/4 and the diffusion code CITATION. The input spectrum covariance information required by MSITER code was also calculated from the CITATION output. Comparison between calculated and adjusted spectra shows good agreement. Integral parameters derived from the adjusted spectra, which includes flux densities over different energy regions and predicted reaction rates were evaluated and compared for the different regions.
Thermal Neutron Scattering and Transport in Methane at 20K
Authors: Tewari S.P. , Sood Jyoti , Tandon Poonam , Silotia Poonam
Published: July 2007

A thermal neutron scattering kernel in methane has been suggested which takes into account the contributions from both phonon and libron exchange processes. The observed total neutron scattering cross-section can be explained at 20 K, when as many as fourteen libron exchange processes are considered in the thermal neutron scattering kernel along with phonon exchange processes upto two quanta. Using the suggested scattering kernel, thermal neutron transport under different conditions like time dependent, space dependent and steady state neutron spectra have been studied at 20 K. The results of these studies are quite different from other hydrogenous moderators like ice, etc. The production of intense beams of cold neutrons at 20 K and below indicate that normal methane is a better moderator for finite sizes of the assembly while heavy methane is a better source of cold neutrons for infinite sizes of the assembly as compared to other hydrogenous moderators.
Neutron Diffraction Measurements of Residual Stress in Sintered Automotive Components Obtained by Net-shape Forming
Authors: Albertini G. , Annibali G. , Fiori F. , Marcantoni M. , Quadrini E. , Turquier F.
Published: July 2007

The residual stress state after the sintering process is investigated in a net-shaped gear using neutron diffraction. The tooth and throat regions are considered in particular. As a general trend, compressive stresses are found at the surface and tensile stresses are found in the bulk. The occurrence of compressive stresses at the surface is of great importance to counteract the external forces occurring during the service conditions. The obtained results are seen at the light of a simple model, considering the spring effect induced by the high pressure and the quench effect induced by the high temperature.
Applied and Residual Strain/stress Measurements on a Dolomite Rock Sample Using Neutron Time-of-flight Diffraction
Authors: Scheffzük CH. , Walther K. , Frischbutter A.
Published: July 2007

Applied and residual strain-stress investigations were carried out on approximately pure polycrystalline dolomite under uniaxial compression and using neutron time-of-flight diffraction. Furthermore, the residual strain/stress behaviour of the sample was measured after each step of loading. Three Bragg reflections of dolomite were used for detailed investigations. They are found to be under compression, both for the loaded and for the relaxed states. Young’s moduli were determined experimentally.
Neutron and Synchrotron Evaluation of Residual Stresses in Coatings
Authors: Carradó Adele , Sprauel Jean-Michel , Barrallier Laurent , Lodini Alain
Published: July 2007

The present study is dedicated to the evaluation of residual stresses at surfaces, in the bulk of materials and at interfaces, by classical X-ray and neutron diffraction and high-energy synchrotron measurements. It is mainly focused on the improvement of these experimental techniques. The new developed methods have been applied to a coating that consists of leucite moulded on a Palladium alloy substrate. These materials are employed in dental applications.
Use of Synchrotron Radiation in the Analysis of Strains Near the Interface Between a Plasma-Sprayed Hydroxyapatite Coating and a Ti-6AI-4V Substrate
Authors: Cofino B. , Braham C. , Millet P. , Lodini A.
Published: July 2007

Plasma sprayed hydroxyapatite coatings on titanium alloy are often used in prosthetic implants. The metallic substrate gives the implant good mechanical strength which is combined with good biocompatibility and osteointegration of the ceramic coating. However there is sometimes a failure of the implant, and this failure is often located at the interface between the titanium alloy and the hydroxyapatite coating. Knowledge about the strains in the materials near the interface seems to be an important step in understanding why the failure occurs. Synchrotron radiation, using Beamline BM16 at the European Synchrotron Radiation Facility (Grenoble, France), has been used to measure local strains near the interface, down to 10 µm in resolution, between a plasma-sprayed hydroxyapatite coating and a titanium alloy substrate. The influence of sand blasting and shot peening on the strains from the surface to the depth of the titanium alloy before coating has been investigated, along with the strains around the interface from the surface of the hydroxyapatite to in-depth in the titanium alloy.
Residual Stress in Weldments
Authors: Webster G.A. , Wimpory R.C.
Published: July 2007

Undesirable residual stresses can be introduced into engineering components during welding. These stresses can affect the load carrying capacity and resistance to fracture of components. In order to quantify their effect it is necessary to know their magnitude and distribution. Several techniques are available for measuring the residual stresses in welds. However, only neutron diffraction is capable of determining these stresses non-destructively within the interior of components. In this paper, neutron diffraction is used to obtain the residual stress profiles generated in a selection of weldments manufactured by different processes. The processes considered include linear friction, inertia, electron beam and manual metal arc welding. It is found that these welding techniques typically produce a triaxial tensile residual stress field in the weld metal which decays rapidly through the heat affected zone to produce balancing compression in the parent material.
The Sin2 Ψ-method in Pulsed Neutron Transmission
Authors: Steuwer A. , Withers P.J. , Santisteban J.R. , Edwards L. , Fitzpatrick M.E. , Daymond M.R. , Johnson M.W.
Published: July 2007

The transmission spectrum of thermal neutrons through polycrystalline samples as a function of wavelength displays sudden increases in intensity known as Bragg edges. These edges occur whenever the wavelength ceases to fulfil the Bragg condition for coherent scattering at Bragg angle 2Θ = 180°. The shape and position of these edges contain information about the stress state present in the sample. The transmission method has two key advantages over conventional neutron diffraction. For samples with essentially one or two-dimensional stress-fields the use of pixellated detector arrays enables simultaneous, therefore very fast, spatial imaging of strains. At the same time it allows for the determination of the unstrained lattice spacing as well as stresses in the sample by evaluating a set of strain images taken at different sample inclinations, similar to the sin2 Ψ-technique of X-ray diffraction. We show how this technique has been successfully employed to determine accurately the unstrained lattice parameter and stresses in bi-axially stressed samples.
Influence of the Residual Stresses on the Mechanical Behavior of Advanced Composite Parts
Authors: Cherouat A. , Gong X.L. , Sicot O. , Lu J.
Published: July 2007

The cooling condition in the forming process (resin transfer molding (RTM), structural resin injection molding (SRIM), laying-up) plays an important part in residual stress distribution in the advanced composite pieces. The residual stresses, which are induced during the cool-down process following high temperature consolidation, result from the coefficient of thermal expansion (CTE) mismatch between plies. This paper describes the development of a finite element method to simulate the prediction of residual stresses and strains fields induced by cool-down process. In this research we used incremental hole drilling method combined with acoustic emission to understand the chronology of damage events, the development of damage modes (matrix cracks, laminate delamination and fibers fractures). The laminate plates [02/902]s, was polymerized with three different cooling conditions (fast, normal and slow). Specimens cut from these plates were tested to measure their tensile strength and to investigate the influence of residual stresses on the mechanical behavior of laminate structures.
Scattering Experiments Under Uniaxial Stress of Modulated Phases
Authors: Marmeggi J.-CL.
Published: July 2007

Neutron diffraction has the potential to provide information deep below the surface of real materials. Both mechanical and thermal loading are considered. Firstly the experimental set up to realise the uniaxial stress is described. Samples of NiO and alpha-uranium were submitted to an external uniaxial stress that gives complementary information in neutrons and X-rays scattering. Reversible or displacive phase transformations take place reversibly through the transition. Finally for high spatial resolution stress it would be necessary to use high energy X-ray synchrotron facilities to optimise effectively the stress rig.
POLDI—the New Time-of-flight Diffractometer at PSI for Strain-field Measurements
Authors: Stuhr U.
Published: July 2007

The new time-of-flight diffractometer for strain-field measurements POLDI at the continuous spallation source SINQ at PSI is presented. High intensity and high resolution are achieved simultaneously by allowing pulse overlapping. The dependence of the arrival time of the neutrons in the detector on the scattering angle allows the calculation of the diffraction pattern. The basic concept and the main instrument components are presented in this paper.
Evaluation by Neutron Diffraction Method of the Level of Stresses in Ti/SiC Bling
Authors: Levy-Tubiana R. , Molliex L. , Lodini A.
Published: July 2007

Diffraction-based stress measurement techniques have been widely applied to the study of two-phase and composite materials [1,2]. Diffraction is particularly useful and that allows the strains (and hence stresses) to be measured independently in both phases of the material, which can give useful information on mechanical behavior. We analyze a bling in titanium reinforced by fibers of SiC: strains are measured, stresses of each phase and macrostresses are quantified.
Validation of a Computer Code for Use in the Mechanical Design of Spallation Neutron Targets
Authors: Montanez Paul A. , Sievers Peter
Published: July 2007

The present work concentrates on comparing a numerical code and a closed-form analytic solution for determining transient stress waves generated by an impinging, high-intensity proton pulse onto a perfectly elastic solid cylindrical target. The comparison of the two methods serves both to benchmark the physics and numerical methods of the codes, and to verify them against analytic expressions that can be established for calculating the response of the target for simple cases of loading and geometry. Additionally, the comparison elucidated the effects of approximations used in the computation of the analytic results. Two load cases have been investigated: (1) an instantaneously uniform thermal loading along the central core, and (2) a ramped and uniform thermal load applied along the central core. By validating these analytical results, the closed-form solution may be confidently used to “bound” the solution prior to initiating more detailed and comprehensive numerical studies.
Criteria for Determining Element Size and Time Step for Thermal Shock Simulation
Authors: Zheng Jinyang , Taleyarkhan Rusi P. , Kim Seokho H.
Published: July 2007

Rapid energy deposition into spallation source targets can lead to their temperature rise at enormous rates, giving rise to dynamic thermoelastic stresses. Understanding and predicting the resulting stress waves are crucial for robust design and safe operation of such devices. To simulate the thermal shock phenomenon accurately, many factors should be carefully considered, such as geometry, surface condition, energy deposition profile, equation of state, possible cavitation, viscous damping, rate-dependent constitutive equation, element size, and time step. In this paper a closed form expression for the induced stress in slender bars with distributed energy deposition has been directly derived; it is then used to test the accuracy of computed results with FEA codes. It was found that significant errors can occur unless care is taken to restrict element size and time step depending on the boundary conditions, steepness of temperature profiles and rise rate. Criteria have been proposed for determining the above two parameters. Numerical simulation with the well-established ANSYS5.5 code system showed that excellent results could be achieved if the proposed criteria are met.
Polarized neutrons for pulsed neutron sources
Authors: Anderson Ian.S. , Cook Jeremy , Felcher Gain , Gentile Tom , Greene Geoffrey , Klose Frank , Koetzle Tom , Lelievre-Berna Eddy , Parizzi Andre , Pynn Roger , Zhao Jinkui
Published: July 2007

Polarized neutrons provide a powerful tool for research at today’s continuous neutron sources, permitting unique information to be obtained from neutron-scattering experiments and in the area of fundamental neutron physics. The information obtained is indispensable to important areas of current research such as magnetism, spin fluctuations in correlated-electron materials, nanoscience, astrophysics, and cosmology. Unfortunately, the polarized neutron capabilities that already exist at reactor neutron sources, mainly in Europe, cannot be transferred directly to pulsed spallation sources because many of the devices used at reactors to manipulate neutron spins operate only at a single neutron wavelength or with a neutron beam of limited divergence. Both of these restrictions must be overcome for devices to be useful at pulsed spallation sources. This report identifies the significant R&D efforts that will be required to achieve these goals. These efforts must be undertaken now, if they are to be useful early in the lifetime of the spallation neutron source (SNS) or its Japanese counterpart, Japanese proton accelerator research complex (J-PARC). A workshop on the use of polarized neutrons at pulsed neutron sources was held on February 10–13, 2003, in Gaithersburg, Maryland, USA. Sixty-one scientists representing work in Europe, Japan and the US attended the workshop whose purpose was to discuss research opportunities with polarized neutrons at pulsed spallation sources and to develop a roadmap for the technology R&D required to facilitate this type of work. Well-funded efforts to develop polarization capabilities are under way in both Japan and Europe. The workshop concluded that it makes sense for the US to collaborate with these activities, as well as to develop its own R&D program, as it is beginning to do. There is ample opportunity within the R&D portfolio outlined in this report for research activities both at universities and at national neutron centers. Synergy between these efforts will contribute to other goals such as the development of a robust programme of instrument innovation that will be required at new pulsed sources to maintain their vitality in future decades.
Phase space transformation on ultra cold neutrons
Authors: Boehm M. , Henggeler W. , Allenspach P. , Furrer A.
Published: July 2007

We present the results of a Monte Carlo simulation and analytical calculations for a phase space transformer, which accelerates ultra-cold neutrons (UCNs) to cold or thermal neutron energies. We show that due to the sharp energy distribution of UCN’s this kind of neutron device is able to produce monochromatized neutrons with intensities competing today’s most performing time-of-flight instruments, an energy resolution of the order of δE/E ∼ 0.3%, and a horizontal divergency of ∼2° at the planned spallation source for UCN’s (PSI, Switzerland).
The 2D small angle detector project at the FOCUS time-of-flight spectrometer at SINQ
Authors: Jurányi F. , Holitzner L. , Schlumpf N. , Greuter U. , Gahl T. , Janssen S. , Mesot J. , Hempelmann R.
Published: July 2007

A small-angle detector will complete the performance of the cold time-of-flight spectrometer FOCUS at the Swiss Spallation Source SINQ of the Paul Scherrer Institute, Villigen, Switzerland. It is constructed from position-sensitive 3He tubes located 2.5 m away from the sample, and covers an area of about 95×70 cm2 with a spatial resolution of approximately 1.5 cm. The 2D detector is located within a vacuum chamber, next to the argon chamber of the existing large angle detectors, and covers an angular range from 2 to 22°. Commissioning of the 2D small angle detector will start in spring 2006.
Toward the commissioning phase of the BRIllouin spectrometer BRISP
Authors: Aisa D. , Aisa S. , Babucci E. , Barocchi F. , Cunsolo A. , D’anca F. , de Francesco A. , Formisano F. , Gahl T. , Guarini E. , Laloni A. , Mutka H. , Orecchini A. , Petrillo C. , Pilgrim W.-C. , Piluso A. , Sacchetti F. , Suck J.-B. , Venturi G.
Published: July 2007

The construction project of the novel thermal neutron Brillouin spectrometer (BRISP) is entering its commissioning period. After a brief review of the scientific motivation and the technical components of the instrument, we present here a historical overview of the installation steps that have gradually brought such a difficult project into the present important phase.
A High-Resolution Inverted Time-Of-Flight Spectrometer For Reactor Cold-Sources
Authors: Kearley G.J. , Trouw F.
Published: July 2007

At neutron energies below about 3 meV, a disk chopper can produce shorter pulses than spallation-source cold moderators. The development of mica crystal-analyzer spectrometers at spallation sources has led to the use of energies well below 1 meV, where the shorter pulse of the disk chopper at a reactor cold-source can be exploited to build an instrument almost ten times shorter than its spallation-source counterpart. A short flight-path instrument has advantages for energy-range, total count-rate, and cost.
Coherent Scattering Length Measurements on Krypton with Neutron Interferometry at a Small Reactor
Authors: Terburg B.P. , Verkerk P. , Jericha E. , Zawisky M.
Published: July 2007

We carried out neutron interferometry measurements to determine the coherent neutron scattering lengths of gaseous natural krypton and 86Kr. Measurements were performed at a 250 kW TRIGA reactor. The accuracy of the results is restricted by the stability of the set-up and not by the limited neutron flux. The results obtained at this reactor prove that neutron interferometry is feasible even at small neutron sources, provided that a stable set-up is used.
Neutron Irradiation Experiments for Fission and Fusion Reactor Materials Studies
Authors: Thoms K.R. , Rowcliffe A.F.
Published: July 2007

The process of developing materials for use in energy-conversion machines based upon fission or fusion reactors is critically dependent upon subjecting those materials to the thermal and neutronic environment that reproduces, as closely as possible, that expected in a power-producing reactor. Materials scientists make use of sophisticated capsule-type irradiation experiments to place test specimens in various fission reactors to achieve that desired environment. Neutron radiation damage and typical experimental devices are discussed in terms of three major US fission and fusion reactor programs.
Neutron Reflectometry as Optical Imaging
Authors: Hamilton W.A. , Hayter John B. , Smith G.S.
Published: July 2007

In this paper we show how a specularly reflecting mirror sample at grazing incidence may be treated as a simple imaging element, akin to a slit camera. An analysis of the imaging properties leads to a new and efficient means of measuring neutron reflectivity. The resolution of a reflectivity curve obtained by this scheme depends only on the geometry of the sample-to-detector arrangement, and is largely independent of incident beam collimation. In the absence of significant off-specular scattering, this method of data reduction allows a neutron reflectometer equipped with a linear position sensitive detector to use the higher intensity of a loosely collimated beam while achieving excellent resolution. To illustrate the principle, we present raw and reduced reflection data taken on the first runs of the newly commissioned neutron reflectometer at the High-Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL).
Modulation Spectroscopy of Neutrons Conceptual Study of a New TOF-Approach to Phonons
Authors: Hiismäki P.
Published: July 2007

The problem of measuring phonon dispersion curves by neutron time-of-flight is considered as a process of classification of probabilistic rather than deterministic events. The measuring system requires a pulsed source, a sample, placed at a goniometer, a bank of detectors at constant radius from the sample, a Fourier chopper installed between the source and the sample, and a special data acquisition system. It is shown that three different scans can be accomplished by combining in three distinct ways the delayed state of the source pulse and the delayed state of the chopper. Two of them are the familiar direct and indirect geometry scans. The third one. the so-called radial scan takes place along straight radial lines to the origin of the momentum space, possible in the deterministic classification scheme only, if dynamically oriented crystal analyzer is used. If the radial scan is chosen to pass through any of the reciprocal lattice points of the crystal, next or second next to the origin, the polarization factor is 1 for the longitudinal phonons, but 0 for the transversal phonons, which thus give no contribution at all.
Neutron Imaging with Scintillating-Glass Fiber-Optic Plates
Authors: Ottonello P. , Rottigni G.A. , Zanella G. , Zannoni R.
Published: July 2007

A review is presented about the use of scintillating glass optical fibers for neutron imaging. The fibers are assembled in bundles to form plates coupled to integrating image detectors (CCDs). The scintillating glass core of the single fibers, which are oriented in the direction of impinging neutrons, is sensitive to neutrons. Scintillating glasses containing lithium and doped with terbium or europium are the most convenient for detection of slow neutrons. Experimental results are reported.
A Position Sensitive Gd Detector for Thermal Neutrons
Authors: Bruckner G. , Rauch H.
Published: July 2007

Si-strip detectors show qualities which are desirable in many neutron experiments, like excellent position– and time resolution and a low sensitivity to background radiation. To demonstrate the feasibility of this detector type for the detection of thermal neutrons, we tested a prototype of a one dimensional position sensitive neutron detector based on a Si-strip detector with a Gd-foil converter. A complete system consisting of the detector with VLSI electronics and an on-line data acquisition system has been constructed and tested. We present the first results of the measured position resolution and detector efficiency for neutrons with 1.1 Å wavelength.
Space-Time Symmetry Violation and Neutron-Polarization Rotation
Authors: Masuda Y.
Published: July 2007

P-violating neutron-spin rotation was firstly observed in a p-wave neutron-nucleus resonance. A lanthanum target was placed in a superconducting box. The incident neutron spin was set at transverse direction to the neutron beam in the horizontal plane. The neutron spin rotates around its momentum axis in the presence of P-violating interaction. The neutron spin passes through a Meissner sheet without any change in its direction. The rotation angle was converted to a projection angle on a vertical magnetic field in the downstream, which was analyzed by a polarized 3He neutron polarimeter. The experimental result of the P-violating rotation is consistent with the theory of s- and p-wave parity mixing in the compound nucleus state. For the T-violation experiment, measurement of T-odd triple correlation between the neutron spin, the neutron momentum and the nuclear spin, a new method is proposed, which greatly reduces systematic errors. The experiment can be compared with the neutron electric dipole moment. Target-nucleus polarization was developed for the T-violation experiment by using a dynamic nuclear polarization. A large lanthanum nuclear polarization was obtained.
Polarisation Analysis of Neutron Reflectivity from Magnetic Thin Films
Authors: Fermon C. , Miramond C. , Ott F. , Saux G.
Published: July 2007

We summarise the theory of polarised neutron reflectivity and describe the PADA reflectometer at the Orphée reactor at Saclay France. We then discuss some experimental difficulties and highlight how this apparatus can be applied to the study of thin magnetic films. Finally, we give an example of a recent experiment on Au/Co/Au trilayers.
Comparison Between a Time-of-Flight and a Monochromatic Neutron Reflectometer at a Continuous Neutron Source
Authors: de Haan V.-O. , van Well A.A.
Published: July 2007

A comparison is made between a time-of-flight neutron reflectometer and a monochromatic neutron reflectometer, both installed at the same continuous neutron source. It is shown that the measuring times, to obtain similar results, are approximately the same.
Impediments to Efficient Through-Surface Strain Scanning
Authors: Webster P.J. , Mills G. , Wang X.D. , Kang W.P. , Holden T.M.
Published: July 2007

The efficient measurement of through-surface residual strains using multidetector neutron strain scanners is constrained by instrumental effects which arise when the ‘gauge volume’ is only partly immersed in the sample. The three principal causes, wavelength variation across the incident beam, lateral displacement of the ‘effective centre’ of the gauge volume relative to the detector, and asymmetric clipping of the diffracted peak profile are discussed and quantified. Results are described of a systematic quantitative investigation of the instrumental aberrations that affect the L-3 spectrometer operating in its strain scanning mode at the NRU reactor at AECL, Chalk River, Canada. Comparisons are made with theoretical models which accurately predict the observed aberrations. Techniques for reducing and correcting for the effects are discussed.
Multilayers for Neutron Optics
Authors: Anderson I.S. , Schärpf O. , Høghøj P. , Ageron P.
Published: July 2007

A condensed review of theory, application, fabrication, and characterization of multilayers in neutron optics is given. The main results of kinematical theory for periodic multilayers are quoted. The application of multilayers as monochromators, band pass filters and supermirrors is discussed.
Polarizing Supermirrors
Authors: Böni P.
Published: July 2007

Sputtering techniques allow, by means of alloying and reactive processes, to produce artificial multilayers on a nano-meter scale with non-stochiometric compositions. Hence it is possible to adjust the index of refraction of individual layers. This property is particularly important for the fabrication of polarizing mirrors. In addition, composite layers are usually smoother and less prone to interdiffusion, i.e., more-stable with temperature. For example, Fe50Co48V2/TiNx supermirrors survive temperatures as high as T ≃ 230°C. Moreover, by using anisotropic sputtering conditions, remanent mirrors can be produced with the magnetization direction pointing along any desired direction, thus allowing the fabrication of spin selectors for applications in zero field environments.
The Backscattering Instrument MUSICAL and Test Experiments
Authors: Dohmen L. , Lang M. , Martin D. , Carlile C.J. , Alefeld B.
Published: July 2007

MUSICAL represents a concept for a neutron backscattering instrument designed to be used on a pulsed neutron source. By using many crystals as monochromators, the multiplexing effect should give an intensity gain compared to a conventional single monochromator spectrometer, which is proportional to the number of crystals. A novel multiple silicon crystal is used as the monochromator. Test experiments were performed using 21 unpolished silicon crystals each separated by 4.7 cm and temperature differences δT of 10 °C or 20 °C between neighbouring crystals. As expected the resolution function has a complicated structure. The energy width is estimated to be 400 neV which is close to the best energy resolution available on current backscattering spectrometers.
Wafer Stacks As Neutron Monochromators
Authors: Vogt T. , Wildgruber U. , Passell L. , Cheung S.
Published: July 2007

A recently developed process to create a spatially homogeneous but anisotropic mosaic structure in formerly perfect Ge wafers opened the way to combine these wafers to stacks and build large composite neutron monochromators for high resolution neutron powder and single crystal diffraction.
Long-Pulse Spallation Source Neutronic Performance
Authors: Russell Gary J. , Pitcher Eric J. , Ferguson Phillip D. , Patton Bruce W.
Published: July 2007

There are potential gains of about a factor of seven in the time-average neutron brightness for a coupled liquid H2 moderator compared to a decoupled one, and a factor of around five for a H20 moderator. However, these gains come at the expense of putting “tails” on the neutron pulses. The particulars of the neutron pulses from a moderator (e.g., energy-dependent rise times, peak intensities, pulse widths, and decay constant(s) of the tails) are crucial parameters for designing instruments and estimating their performance at an LPSS. The spallation target system designer can alter moderator neutronic performance by: (a) the choice of target material and geometry; (b) proper selection of the moderator material and geometry; (c) varying the target–moderator geometry; (d) the choice of reflector material(s); (e) the presence/absence of decouplers and liners; and (f) the proton pulse width. A 1-MW Long-Pulse Spallation Source (LPSS) has world-class neutronic performance. We show that the calculated performance of a liquid H2 moderator at a 1-MW LPSS is equivalent to one-fourth the calculated performance of the best liquid D2 moderator at the Institut Laue Langevin (ILL) reactor.
Reflectometry at a Long Pulse Spallation Source
Authors: Fritzsche H. , Guy C. , Stride J. , Mezei F.
Published: July 2007

The layout criteria for a reflectometer at a long pulse spallation source (LPSS) are discussed. It is shown how the most important instrument parameter, the wished resolution of the measured reflectivity profile, determines the choice of the wavelength and available wavelength band, the length of the instrument and the position of the disc choppers, which are necessary for applying the time-of-flight method. Using 4 disc choppers it is possible to measure the same spectrum with different resolutions without changing the beam geometry and the available wavelength band. All considerations are tested with Monte Carlo simulations, which were performed with a 2 ms pulse of a source working at 25 Hz.
Laue Diffractometer at a Long Pulse Spallation Source
Authors: Ehlers G. , Mezei F.
Published: July 2007

The performance of a Laue diffractometer at a Long Pulse Spallation Source is illustrated by an example. The instrument is built at a thermal f = 25 Hz source and uses a neutron guide, which is 70m long, and a wavelength band of 2 Å at the position of the sample. The pulse of 2ms of the source can be chopped to provide a variable resolution of the order δλ/λ = 1–3%. The instrument is suited for the investigation of samples with unit cell volumes of the order of 100–1000 Å3 at a medium time resolution. For an averaged spallation beam power of 5MW the neutron flux at the sample position is estimated to amount to Φ = 3–8 × 107 n cm−2 s−1, depending on the chopper speed. The performance of the instrument is demonstrated by a Monte Carlo simulation technique. Calculations with an idealised model sample focus on the peak-to-background ratio and the ability to resolve Bragg peaks.
Optimization Study of a Simple Geometry Spallation Source Target Design
Authors: Cser L. , Vértes P.
Published: July 2007

Using a Monte Carlo simulation method for calculating the proton and neutron flux distribution a symmetrical geometry – two targets surrounding a side moderator – is proposed for the target station of a spallation source. Mesitylene possessing high stability against radiation damage is discussed as a possible material for the cold source.
Experimental Studies on Neutronics of Coupled Grooved Liquid-Hydrogen Moderator for Long Pulse Spallation Sources
Authors: Ogawa Y. , Kiyanagi Y. , Furusaka M. , Watanabe N.
Published: July 2007

The neutronic performance of a coupled grooved moderator of liquid-hydrogen was experimentally studied and from the measured neutronic performance it was proved that this type of grooved moderator is useful not only for short pulse spallation sources but also for long pulse spallation sources.
Two-Axis Neutron and X-Ray Reflectivity: How to Avoid Alignment Pitfalls and How to Correct for Them
Authors: Bouwman Wim G. , Vigild Martin E. , Findeisen Eberhard , Kjaer Kristian , Feidenhans’l Robert , Mol Elisabeth A.L.
Published: July 2007

Sample alignment for neutron (and in some cases x-ray) reflectometry can be complicated due to a coupling between angle and position which occurs when slits are used to define the path of the beam. Misalignments in sample position or sample rotation angle give rise to systematic errors in the experiments. By measuring the reflectivity both from the back and from the front faces of the sample (twin reflectometry) these alignment errors can be detected and corrected for.
A Review of a Synthetic Scattering Function Approach to the Thermal and Cold Neutron Scattering Kernels of Moderator Materials
Authors: Granada J.R. , Gillette V.H.
Published: July 2007

In the frame of a Synthetic Scattering Function (SSF), the incoherent interaction of slow neutrons with hydrogeneous materials can be described in a simple way. The main advantages of this model reside in the analytical expressions that it produces for multiple physics parameters of specific interest to the field of Neutron and Reactor Physics. These parameters include double-differential cross sections, energy-transfer kernels, and total cross sections, which in turn allow the evaluation of neutron scattering and transport properties. The possibility of calculating those quantities in a fast and accurate way, permits the production of group constants for any specific material, at any temperature, any degree in the Legendre expansion, and over any required energy mesh.
Efficiency of a Tunable Pyrolytic Graphite Neutron Filter
Authors: Vorderwisch P. , Stuhr U. , Hautecler S.
Published: July 2007

The performance of a tunable pyrolytic graphite filter with a cold neutron triple-axis-spectrometer is presented. A filter of 25mm thickness gives an efficient attenuation of the second order beam contamination in the nominal neutron wavevector range 1.4 Å−1 < k ≤ 2.6 Å−1.
The Measurement of Residual Macrostresses using Neutrons
Authors: Krawitz A.D. , Winholtz R.A.
Published: July 2007

The basic goal of this paper is to convey essential information on neutron macrostress measurements to potential users of the method. After a discussion on residual stresses, the use of neutrons, which makes possible the measurement of triaxial macrostresses through the depth of engineering components due to the lower absorption of neutrons by most engineering materials, is presented. This is followed by a discussion on the physical and analytical basis of the use of diffraction for the measurement of such stresses. Next is a discussion on experimental aspects relevant to potential users, including probe volumes, stress-free reference standards, sample quality, errors, and the determination of full stress tensors. Lastly, an example of the determination of residual macrostress tensors in a welded cylindrical section of a solid rocket motor casing is presented.
Spatial Spin-Resonance of Polarized Neutrons in Period-Modulated Static Magnetic Fields
Authors: Grigoriev S.V. , Klimko S.A. , Kopitsa G.P. , Runov V.V.
Published: July 2007

Spatial spin-resonance for the monochromatization or spectrum shaping of polarized neutrons is investigated in a system of mutually perpendicular magnetic fields: a constant guiding magnetic field and a static periodic magnetic field whose spatial periodicity is modulated. It is shown that the period modulation of the spatially alternating field as well as the modulation of the guiding magnetic field allows a change in the resonator line-width over a wide range. The harmonic approach to the modulation of an effective magnetic field is considered in a reference frame connected with the neutron. A comparative analysis as well as computer simulation are performed for the spectra obtained by means of different modulation methods.
A Third Route to the Formation and Decomposition of Siloxane Structures. To Siloxanes Through Silanones
Authors: Voronkov M.C.
Published: July 2007

On the basis of his own and literature data, the author considers and gives theoretical substantiation to the routes for the formation and decomposition of linear and cyclic oligo- and polysiloxanes through an intramolecular reaction of geminal fragmentation of > Si(OR)X groups with the intermediate formation (α-elimination) of short-lived silanones R2 Si = O. The latter further undergoes polymerization or insertion into Si–X bonds (X = O, Cl, etc.) of trapping reagents.
Complexes of Indium (III) with Tripodal Schiff Base Ligands
Authors: Parr Jonathan , Ross Andrew T. , Slawin Alexandra M.Z.
Published: July 2007

The interaction of In (III) with tripodal Schiff base ligands (L1–6) prepared from the condensation of substituted salicylaldehydes with tris(2-aminoethy1)amine gives a range of neutral complexes of the type [In (III) (L)] (salicylaldehyde L1, o-vanillin L2, 5- methoxysalicylaldehyde L3, 5-nitrosalicylaldehyde L4, 3,5-di-t-butylsalicylaldehyde L5, 5-bromosalicylaldehyde L6). These complexes were investigated spectroscopically, and in two cases by single crystal X-ray diffraction, and are found to have heptacoordinate In (III) centres. In (III) (L4) triclinic, P1(#2), a = 11.766(3), b = 16.15(1), c = 9.283(5)Å, α = 98.05(5), β = 102.76(3), γ= 100.23(4)°, Z = 2,5235 reflections, R = 0.114: In (III)(L5) triclinic, P1(#2), a = 16.066(4), b = 23.293(3), c = 14.889(3)Å, α = 103.38(1), β = 92.84 (2), γ = 95.22(2)°, Z = 4, 16655 reflections, R = 0.072.
The Syntheses and Characterization of the Bulky Terphenyl Silanes and Chlorosilanes 2,6-Mes2C6H3SiCl3, 2,6-Trip2C6H3SiCl3, 2,6-Mes2C6H3SiHCl2, 2,6-Trip2C6H3SiHCl2, 2,6-Mes2C6H3SiH3, 2,6-Trip2C6H3SiH3 and 2,6-Mes2C6H3SiC12SiC13
Authors: Simons Richard S. , Haubrich Scott T. , Mork Benjamin V. , Niemeyer Mark , Power Philip P.
Published: July 2007

The synthesis and characterization of the primary terphenyl silanes and chlorosilanes 2,6-Mes2C6H3SiCl3 (la), 2,6-Trip2C6H3SiHC3 (lb), 2,6-Mes2C6H3SiHCl2 (2a), 2,6-Trip2C6H3. SiHC12 (2b), 2,6-Mes2C6H3SiH3 (3a), 2,6-Trip2C6SiH3 (3b) and 2,6-Mes2C6H3siCl2-SiCl3 (4), (where Mes = 2,4,6-Me3C6H2 and Trip = 2,4,6-i-Pr3C6H2) are described. Compounds (la, lb), (2a, 2b) and (4) were prepared by the reaction between SiC14, SiHCl3 or Si2C16, respectively, and the appropriate aryl lithium reagent (2,6-Mes2C6H3Li or 2,6-Trip2C6H3Li·OEt2). Compounds (3a) and (3b) were prepared by reduction of (1a) and (1b) with LiA1H4, respectively. The derivatives (la) – (3a) were characterized by 1H, 13C, 29Si NMR and IR spectroscopy. The structures of (la), (lb) and (4) have been determined. Crystal data with Cu Kα (λ = 1.54178 Å) at 130 K: (la), a = 9.074(2) Å, b = 16.681(3) Å, c = 15.842 (3) Å, β = 105.20(3)°, V = 2313.9(8) Å3, Z = 4, space group P21/c, 2772 (I > 2σ(I)) data, R = 0.042; (lb), a = 12.197(2) Å, b = 25.602(5) Å, c = 11.098(2) Å, V = 3465.5(11) Å3, Z = 4, space group Pnma, 2131 (I > 2σ(I)) data, R = 0.061; (4), a = 10.799(2) Å, b = 15.355(3) Å, c = 16.724(3) Å, β = 106.907(13)°, V = 2653.2(8) Å3, Z = 4, space group P21/n, 2852 (I > 2σ(I)) data, R = 0.047.
Chelated Anionic Aluminum
Authors: Hill Michael S. , Atwood David A.
Published: July 2007

Two equivalents of the bidentate ligands, 2,4-(R)2-6-(CH2NHR′)PhOH where R′ = alkyl and R = H (L1) and tBu(L2) are combined with LiA1H4 to form unique chelated aluminates of the form [(L1)2Al]Li(THG)2 (R′ = iPr (l), iBu (2), tBu (3), Dipp (4) (Dipp = 2,6-(iPr)2Ph)) and [(L2)2A1]Li(THF)2 (R′ = iPr (5), iBu (6), tBu (7)). Compound 7 undergoes a salt elimination when combined with Me2A1C1 to form the bimetallic derivative, (L2)2A1 (A1Me2) (R′ = tBu (8)). By comparison a related reaction with [ArO4Al][Li(thf)4] (Ar = 2,4-(tBu)2Ph (9)) leads to elimination of one of the aryloxide groups and the consequent formation of neutral species. All of the compounds were characterized by Mp, analyses, 1H NMR, IR and, in the case of 4 and 7–9, by X-ray crystallography.
Synthesis, Crystal and Molecular Structure of 1,3,4,5-Tetramethylimidazolium Tetrabromoindium(III)
Authors: Hibbs David E. , Hursthouse Michael B. , Jones Cameron , Smithies Neil A.
Published: July 2007

Treatment of a 2:l mixture of InBr3 and H20 with 1 equivalent of the imidazol-2-ylidene carbene, : CN(Me)C2(Me)2N(Me), affords the title compound, the X-ray crystal structure of which is described. A mechanism is proposed for the formation of [HCN(Me)C2(Me)2N(Me)][InBr4].
Regulation of Microvascular Thromboembolism In Vivo
Authors: OUDE EGBRINK MIRJAM G. A. , VAN GESTEL MIRIAM A. , BROEDERS MARTIJN A. W. , TANGELDER GEERT JAN , HEEMSKERK JOHAN M. W. , RENEMAN ROBERT S. , SLAAF DICK W.
Published: July 2007

Atherothrombosis and embolization are main causes of morbidity and mortality in the Western world. To optimize treatment, better understanding of the factors involved in thromboembolism in vivo is needed. The course and outcome of a thromboembolic process are determined by the local balance between anti and prothrombotic factors. In healthy vessels, endothelial antithrombotic properties prevent blood platelets from interacting with the vessel wall. Upon vessel wall damage or endothelial activation, however, prothrombotic factors temporarily overrule the antithrombotic factors, leading to thrombus formation and embolization. According to this concept, thromboembolism ends when the balance is restored. Animal models on microvascular thromboembolism have provided evidence that the endothelium is eminently involved in the regulation of thromboembolism, and that shear forces are an important determinant of endothelial function. Therefore, in this review focus is on the endothelial regulation of platelet‐vessel wall interactions during thromboembolism in vivo. Anti‐ and prothrombotic properties of vascular endothelium will be discussed, paying special attention to the endothelium‐derived platelet inhibiting substances nitiric oxide (NO) and prostacyclin (PGl2) and to differences between arteriolar and venular endothelium. In addition, the involvement of shear forces in microvascular thromboembolic processes in vivo will be described.