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Showing 1 to 20 of 21 for “"Bragg peaks"”.
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Degradation of proton and carbon Bragg peaks due to density inhomogeneities
… degradation of the sharp distal dose falloff (Bragg peak, BP) caused by inhomogeneous tissue. There is no appropriate model of this effect - which in turn allowed reduction of related dose deposition uncertainties. This thesis develops a comprehensive analytical model of the degradation …
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Structure and melting of small metal particles observed by stem microdiffraction
… according to whether they had distinct Bragg peaks, or were diffuse. Patterns with distinct Bragg peaks showed low rates of twinning, with an upper bound of •14±3% in the case of Au-Ag particles. Diffuse patterns indicate that many of the particles are highly disordered, •88% in the case …
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Structure and melting of small metal particles observed by stem microdiffraction
… according to whether they had distinct Bragg peaks, or were diffuse. Patterns with distinct Bragg peaks showed low rates of twinning, with an upper bound of $\approx$14 $\pm$ 3% in the case of Au-Ag particles. Diffuse patterns indicate that many of the particles are highly disordered, …
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Experimental evaluation of polychromatic neutron diffraction
… powder. The intensity and resolution of the Bragg peaks with the instrument in this configuration were compared to Bragg peaks measured by the same instrument in a monochromatic configuration. The intensity of the polychromatic mode was only comparable to the monochromatic mode with looser …
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X-Ray and Neutron Scattering Studies of Niobium-Hydrogen Alloys Near the Alpha-Prime to Beta Phase Transition
… 300 < T < 473 K. Diffuse scattering close to the Bragg peaks of the BCC (alpha)' phase was measured. The temperature dependence of the scattering was determined in the (alpha)' phase and the changes in the diffuse scattering were determined upon cooling through the (alpha)'-(beta) phase transition.
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Synthesis and physical characterization of thermoelectric single crystals
… reports and a non-zero intensity of forbidden Bragg peaks was noted. Simulations of the effect of Se vacancies in the crystal were executed to explore this last phenomenon. Measurements of the electrical resistivity p and Seebeck coefficient S of the crystal related to the figure of merit ZT = …
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Investigation of superconducting and non-superconducting phases of Na₀Ì£₃CoO₂·1.3H₂0
… dependence behavior in the associated Bragg peaks.
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Antiferromagnetism, ferromagnetism and magnetic phase separation in Bi₂Sr₂O₆â[delta]
… the presence of simultaneous FM and AF magnetic Bragg peaks in the neutron diffraction pattern. Polarized neutron scattering measurements confirm that the FM and AF peaks do not arise from different components of a canted antiferromagnet.
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A powder neutron scattering study of magnetism in potassium copper trifluoride as a function of hydrostatic pressure
… peak intensities of the (001) and (003) magnetic Bragg peaks were not suppressed with pressure. Interestingly, the suppression of the (201) magnetic Bragg peak was observed. These results are believed to be due to a spin reorientation caused by a uniaxial strain component caused by using a clamp …
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Entwicklung von hochauflösenden T2-Messverfahren zur Bestimmung von dreidimensionalen Dosisverteilungen mit Hilfe der MR-Gel-Dosimetrie und deren Anwendung in der Strahlentherapie
… und 3,8 (TGSE) erreicht werden. Die typischen Bragg-Peaks der experimentellen Schwerionentherapie konnten identifiziert werden, allerdings wich die MR-gemessene Dosis im Peak von der geplanten um bis zu 15 ab. In bordotierten, mit Neutronen bestrahlten Gelen konnte nach Normierung keine …
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A Study of the Kinetics of Phase Separation in a Nickel-12.5 at.percent Silicon Alloy
… (satellites) in the vicinity of the fundamental Bragg peaks are observed and their asymmetry suggests that there is a simultaneous variation of concentration and lattice spacing. The origin of these satellites about the fundamental reflections and the 000 peak (SANS) is attributed to the presence …
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Neutron and x-ray scattering studies of layered solids
… by carefully measuring the widths of various Bragg peaks and showing that the broadening can be completely described in terms of residual strain and finite crystallite size. We then conclude by describing the phenomena of terracing for both unstrained and strained-layer superlattices. A model …
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The role of interstitial nitrogen in the precipitation hardening reactions in high-chromium ferritic steels
… revealed the presence of secondary diffraction peaks associated with the Bragg peaks, which comfirmed the formation of Cr-rich phases during ageing at 475°C. The calculated associated lattice parameter measurements allowed estimates of the compositions of the decomposition phases to be made. …
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Semiclassical studies of decoherence produced by scattering
… scattering originates from the existence of Bragg peaks in elastic scattering. The helium atom acts as a quantum mechanical matter wave that is coherent with itself; the well-defined phase relationship of the particle beam at the different spatial positions at surface impact implies the …
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Interplay between charge, spin and orbital ordering in La 1 - Kappa Sr Kappa MnO 3 manganites
… a large amount of diffuse scattering around main Bragg peaks. Using polarization analysis it is shown that the diffuse scattering can be effectively separated to nuclear coherent and paramagnetic scattering, the latter is dominating above the Curie temperature. The diffuse scattering can be well …
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Static and ultrafast optical properties of nanolayered composites : gold nanoparticles embedded in polyelectrolytes
… by X-ray reflectivity measurements, which reveal Bragg peaks up to the seventh order, evidencing the high stratication of the particle layers. In the same measurements pronounced Kiessig fringes were observed, which indicate a low global roughness of the samples. Atomic force microscopy (AFM) …
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Phasenverhalten reiner Stoffe in mesoporösen Silika-Materialien
… Entwicklung der Intensitäten einzelner Bragg-Peaks des 2D-hexagonalen Gitters, die mit einem kristallographischen Modell simuliert werden kann. Das benutzte Modell erlaubt erstmals eine direkte Ermittlung der Dicke des an den Porenwänden adsorbierten Filmes. Die Ergebnisse deuten darauf …
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Self-Consistent Study of Topological Superconductivity in Two-Dimensional Quasicrystals
… TSC in two-dimensional QCs. Although QCs present Bragg peaks, they have no periodicity. We generalize a tight-binding model for TSC in two dimensions, which was originally proposed for square lattice systems, for QCs. As the most fundamental examples, the Penrose and Ammann-Beenker QCs are …
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Electron tomography of defects
… inner angle ( in) that included the rst order Bragg spots (in other series in had been 4-6 B). Extinctions occurred which were dependent on tilt; this produced only weak lines in the reconstruction. Bragg scattering in the ADF STEM image was estimated by summing simulated dark- eld dislocation …
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Phase transformations in highly electrostrictive and magnetostrictive crystals: structural heterogeneity and history dependent phase stability
… x = 25. A splitting of the (2 0 0) and (0 0 2) Bragg peaks observed along the respective transverse directions indicated that Fe-xat.%Ga –crystals' are composed of several crystal grain orientations (or texture structures), which are slightly tilted with respect to each other. In order to …
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