Search results for "angle"
showing 10 items of 1921 documents
Nuclear pion photoproduction in theΔresonance region
1999
A measurement of the /sup 12/C( gamma , pi /sup +/n)/sup 11/B reaction in quasifree pi -production kinematic regimes has been performed using tagged photons in conjunction with large solid angle pi and n detectors. The aim of the experiment was to investigate predicted modifications to the Delta excitation of nucleons and their subsequent propagation and decay, brought about by the nuclear medium. Differential cross sections are presented for photon energies spanning the Delta (1232) excitation region. The measurements are consistent with distorted wave impulse approximation calculations in which the amplitude for proton Delta excitation, followed by Delta propagation and decay to pi /sup +…
The MAMI-project
2008
In the energy region up to one GeV the "racetrack"-microtron /1/ offers an economic way to achieve a 100% duty factor e--beam with a high current (IO0~A) and a well defined energy (Ap/p ~ 10-4). Such an e--beam appears to be ideal for the experimental investigation of the nucleus: coincidence experiments of the type (e,e'x) and (e,e'xy) become possible in a wide kinematical region yielding information about the response of the nucleus to the transferred energy and momentum. By the method of bremsstrahl-tagging, for the f i r s t time, rather intensive ( few times 107/sec) photon beams with high monochromaticity and well known fluxes wi l l be available. To make the best use out of such new …
Nucleation and crystal growth in a suspension of charged colloidal silica spheres with bi-modal size distribution studied by time-resolved ultra-smal…
2014
A suspension of charged colloidal silica spheres exhibiting a bi-modal size distribution of particles, thereby mimicking a binary mixture, was studied using time-resolved ultra-small-angle synchrotron X-ray scattering (USAXS). The sample, consisting of particles of diameters d(A) = (104.7 ± 9.0) nm and d(B) = (88.1 ± 7.8) nm (d(A)/d(B) ≈ 1.2), and with an estimated composition A(0.6(1))B(0.4(1)), was studied with respect to its phase behaviour in dependance of particle number density and interaction, of which the latter was modulated by varying amounts of added base (NaOH). Moreover, its short-range order in the fluid state and its eventual solidification into a long-range ordered colloidal…
The structural properties of soda–silicate sols and of the lime–soda–silicate gel formation
1999
Abstract Alkaline silicate solutions were prepared with varying SiO 2 –Na 2 O ratios, Rm=[SiO 2 ]/[Na 2 O]=2 or 3, with a constant silica concentration equal to 1.5 M. The structure and the number fraction of different silicate molecular species present in the solutions were classically determined for molar ratio Rm=2 using 29 Si nuclear magnetic resonance ( 29 Si NMR). In the case of the sample with Rm=3, for which no NMR data was available, we used small-angle X-ray scattering (SAXS) experiments to get this information. The SAXS model was previously tested with Rm=2 silicate solution. When Ca ++ is added to alkaline silicate solutions, a gel is obtained under well-defined conditions. The …
Acute Type Refinements of Tetrahedral Partitions of Polyhedral Domains
2001
We present a new technique to perform refinements on acute type tetrahedral partitions of a polyhedral domain, provided that the center of the circumscribed sphere around each tetrahedron belongs to the tetrahedron. The resulting family of partitions is of acute type; thus, all the tetrahedra satisfy the maximum angle condition. Both these properties are highly desirable in finite element analysis.
Monotonic solution of heterogeneous anisotropic diffusion problems
2013
Anisotropic problems arise in various areas of science and engineering, for example groundwater transport and petroleum reservoir simulations. The pure diffusive anisotropic time-dependent transport problem is solved on a finite number of nodes, that are selected inside and on the boundary of the given domain, along with possible internal boundaries connecting some of the nodes. An unstructured triangular mesh, that attains the Generalized Anisotropic Delaunay condition for all the triangle sides, is automatically generated by properly connecting all the nodes, starting from an arbitrary initial one. The control volume of each node is the closed polygon given by the union of the midpoint of…
Entanglement control via reservoir engineering in ultracold atomic gases
2013
We study the entanglement of two impurity qubits immersed in a Bose-Einstein condensate (BEC) reservoir. This open quantum system is particularly interesting because the reservoir and system parameters are easily controllable and the reduced dynamics is highly non-Markovian. We show how the model allows for interpolation between a common dephasing scenario and an independent dephasing scenario by simply modifying the wavelength of the superlattice superposed to the BEC, and how this influences the dynamical properties of the impurities. We demonstrate the existence of very rich entanglement dynamics correspondent to different values of reservoir parameters, including phenomena such as entan…
Entanglement dynamics and relaxation in a few-qubit system interacting with random collisions
2008
The dynamics of a single qubit interacting by a sequence of pairwise collisions with an environment consisting of just two more qubits is analyzed. Each collision is modeled in terms of a random unitary operator with a uniform probability distribution described by the uniform Haar measure. We show that the purity of the system qubit as well as the bipartite and the tripartite entanglement reach time averaged equilibrium values characterized by large instantaneous fluctuations.These equilibrium values are independent of the order of collision among the qubits. The relaxation to equilibrium is analyzed also in terms of an ensemble average of random collision histories. Such average allows for…
Inside service-intensive projects: Analyzing inbuilt tensions
2015
The purpose of this research is to identify typical professional and occupational groups in service-intensive projects, and illustrate the inbuilt tensions among them through the lens of institutional theory. The cases used for the study are a wind turbine business and a content management system project business. Our findings suggest that there are two professional groups (problem solvers, technology developers) and two occupational groups (lead generators, relationship developers) involved in these businesses. More importantly, their intergroup tensions are related to different institutionalized logics toward the conception of time (project temporality) and prioritization of different asp…
Multimode OPOs as Sources for Multipartite Entanglement
2009
We present here multimode OPOs as a source of multimode squeezing and multipartite entanglement of continuous-wave light beams, with applications to the engineering of multimode states of light in the spatial and spectral domains.