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  • 25.70.Lm  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 327 (1987), S. 87-100 
    ISSN: 1434-601X
    Keywords: 25.70.-z ; 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Central collisions of heavy nuclei are investigated within the limit of selfconsistent independent single-particle motion in terms of the Wigner transform of the one-body density matrix in space and time. The energy regime considered extends from roughly 15 MeV/u to 150 MeV/u. Special attention is devoted to the relation between energy and momentum of the nucleons in the collision zone of the two nuclei. An initial average energy-momentum distributionf(k;E) is determined within the fully quantal approach which proves to be vital for our understanding of energetic particle production in the very early stage of the heavy-ion reaction. A comparison with related classical quantities shows the peculiar features of quantum dynamics for finite size fermion systems far from equilibrium.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 327 (1987), S. 447-460 
    ISSN: 1434-601X
    Keywords: 25.70.-z ; 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Uehling-Uhlenbeck collision term is derived from coupled equations of motion for the one-body density matrix and the two-body correlation function as obtained from the density-matrix hierarchy. The respective approximations introduced are related with energy and momentum conservation in single nucleon-nucleon collisions and found numerically to be approximately valid for energetic nucleon-nucleon collisions in case of intermediate energy heavy-ion reactions. Primary collision times of nucleons in the dinuclear reaction zone are calculated for various laboratory energies and the approach to local equilibrium is followed in time. Average relaxation times for highly excited finite nuclear systems are found to be considerably shorter than for related infinite nuclear matter problems, however, still too large as to allow for the formation of hot spots in nuclei.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 326 (1987), S. 21-31 
    ISSN: 1434-601X
    Keywords: 25.70.−z ; 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A one-dimensional toy model of two moving finite boxes is analysed with respect to quantal phenomena associated with heavy-ion dynamics at low and intermediate energies. Special attention is payed to the relation between energy and momentum of the nucleons inside and outside the time-dependent mean field. A Wigner transformation of the one-body density matrix in space and time allows for a unique comparison with classical phase-space dynamics. It is found that high momentum components of the nuclear groundstate wave function approximately become on-shell during the heavy-ion reaction. This leads to the emission of energetic nucleons which do not appear classically. It is furthermore shown, that the low lying eigenstates of the dinuclear system for fixed time are only partly occupied throughout the reaction at intermediate energies. This opens up final phase space for nucleons after producing e.g. a pion or energetic photon. Though the present model does not allow for a reliable calculation of double differential nucleon spectra, pion or photon cross sections, it transparently shows the peculiar features of quantum dynamics in heavy-ion collisions.
    Type of Medium: Electronic Resource
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