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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Physics, Section A 463 (1987), S. 239-246 
    ISSN: 0375-9474
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 321 (1985), S. 581-588 
    ISSN: 1434-601X
    Keywords: 24.10.−i ; 21.60.Gx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A coupled-channel resonating group equation for orthogonal channel spaces is derived. It follows from the common resonating group equation by a recursion relation. The recursion extracts from higher channels all overlaps with lower channels, such that the higher channels become corrections to the lower ones. A physically meaningful definition of elimination potentials becomes possible. The new coupled channel resonating group equation allows the derivation ofphysical effective potentials by eliminating small corrections, only. It also allows the derivation oftechnical potentials, i.e. potentials with an unphysical off-shell behaviour, when the dominant part of the equation is eliminated. A numerical example demonstrates that linear dependence of the test function space is not harmful to the new equation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 303 (1981), S. 209-213 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of partly Pauli-forbidden states on elastic nucleus-nucleus scattering is studied in two simplified examples by calculating the time evolution of a wave packet. The numerical results support the notion that partly Pauli-forbidden states may be regarded as the diffuse surface part of a Fermi sphere of relative motion states which can lead to a partial reflection of the incoming wave packet.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Few body systems 1 (1986), S. 37-45 
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A recently developed coupled-channel resonating group method with orthogonalized function spaces is tested. As test example a six-quark three-channel resonating group model is used. The channels are theNN-, ΔΔ- andCC- (“hidden colour”) channels. In earlier calculations without orthogonalization of channel spaces the relative motion function of theNN-channel had a node in theS-wave at approximately 0.5 fm. In the new treatment, in which the ΔΔ- andCC-channels are only orthogonal corrections to theNN-channel, this node is no longer present. The newNN wave function is very similar to the one of the single-channel approximation. Thus, in the one- and three-channel approximation, we consistently find that the six-quark resonating group model does not support the notion of a short-distance node in theNN wave function.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two different 6-quark resonating group models of the deuteron are investigated to study the off-shell property of theN-N interaction. In the first model the quarks interact by a central one-gluon-exchange potential plus confinement potential. The meson-exchange contribution to then-p potential is simulated by a central GaussianN-N potential. In the second model the quarks interact by one-gluon-and one-pion-exchange potentials (central and noncentral) plus confinement potential. A small additional “σ”-exchange potential between neutron and proton binds the deuteron at the correct energy. Several off-shell variants of the two resonating group models are compared with each other by analyzing their elastic electron scattering cross sections. It is found that the standard renormalized version of the resonating group model yields potentials and wave functions that may be considered physical within the limitations of the model. Unitary off-shell transformations, which modify potentials and wave functions in any sizeable way, lead to a disagreement between the charge distribution predicted by the model via analysis of electron scattering and the charge distribution following from the microscopic quark distribution. Both of the 6-quark models support a soft repulsive core of the tripletn-p potential with a core height of around 900 MeV.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Few body systems 5 (1988), S. 107-115 
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An operator formalism is constructed which allows one to calculate a movie of nuclear density plots showing the linear oscillation of two chosen fragments (clusters) in a given ground state or virtual state of a nucleus. The main ingredients of the formalism are the projection of a nuclear wave function onto a chosen antisymmetrized cluster decomposition, and the knowledge that a quantum mechanicalL=0 motion is a linear motion averaged over angles. The formalism is tested and results are discussed in the well-known cases of a shell-model description and a resonating-group-model description of8Be. It is seen that two α-clusters appear even in the surface of the compact harmonic-oscillator shell model ground-state. They are formed with higher probability in the resonating-group-model description of the more realistic8Be virtual state at 92 keV.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 320 (1985), S. 399-404 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The two- and three-cluster fish bone optical model with hard core correlations is derived from the corresponding resonating group model. The nuclear saturation effect is represented by three different features of inter-cluster interactions:i) by the non-local exchange potential,ii) by a reduced attraction in the region of overlapping clusters,iii) by an effective three-cluster potential. Comparability of the microscopic theory with phenomenological models is established by two off-shell transformations which orthogonalize function bases and avoid appearance of artificial three-body forces.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 322 (1985), S. 49-57 
    ISSN: 1434-601X
    Keywords: 21.60.Gx ; 25.10.+s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The recently developed fish bone optical model with saturation has been applied tonα. andαα scattering. Short ranged nucleon-nucleon correlations, which are responsible for nuclear saturation, have an influence both on the local potential part and on the exchange potential. The local potential becomes less attractive in the inner region and steeper in the surface region; it is better represented by a Woods Saxon shape than by a gaussian. A modification of the exchange potential is caused by the effect of short range correlations on the resonating group norm kernel. It is seen that short ranged nucleonnucleon correlations have no dramatic effect on two-cluster optical potentials. The present calculations rather support conventional phenomenological approaches. Together with older results one may conclude that, in multicluster systems, saturation is predominantly carried by three- and multicluster forces.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Computer supported cooperative work 6 (1997), S. 19-51 
    ISSN: 1573-7551
    Keywords: Computer-supported writing ; collaborative editing ; collaborative writing ; cooperative work ; group communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper documents the results of a field test of Instant Update, a collaborative writing tool by a geographically dispersed department at the MITRE Corporation. Thirty-six participants were given Instant Update software and free training and support in exchange for their cooperation with data collection. These participants spent a great deal of time writing and communicating with each other about their written work. They began the pilot test with enthusiasm, using Instant Update for many types of documents and anticipating many benefits. After three months of experience they rated the actual benefits they received from the software lower than they had expected. Their usage became much more refined. They continued to use it for some types of documents, but stopped for others. The collaborative writing software was used successfully to create joint documents that have a consistent format and are produced on a regular basis (such as weekly activity reports) and for documents that provide access to shared information (such as a vacation calendar). It was used less successfully for the production of documents that require a complex work flow and have a changing group of contributors. We concluded that although collaborative writing is difficult to support and the currently available collaborative writing tools need to be improved before they can meet the needs of most co-writers, they are adequate for some types of tasks. Documents that are well defined and are created by experienced users who can cooperate well can benefit from the currently available tools.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 31 (1892), S. 477-480 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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