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  • 25.70.-z  (5)
  • 25.70.−z  (4)
  • 11.30.Qc  (1)
  • 13.75 Gx  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Dynamical and thermal aspects of relativistic heavy-ion collisions (1991)
    Springer
    The European physical journal 340 (1991), S. 287-295 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.−z ; 25.70.Np
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Within a covariant BUU-approach we simulate heavyion collisions at various bombarding energies from 400 MeV/u to 1 GeV/u. We evaluate locally the energymomentum tensorT μv (x), and extract pressures, energydensities and temperatures. The connection of these thermodynamical quantities to experimental observables and their sensitivity to the equation of state is discussed. Furthermore, we investigate the question of local equilibration and evaluate the entropy produced in these reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294677
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Self-consistent truncation of the BBGKY hierarchy on the two-body level (1992)
    Springer
    The European physical journal 342 (1992), S. 161-167 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.Cn ; 25.70.−z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a coupled set of equations for the one-body density matrix and the two-body correlation function consistent with trace relations and conservation laws which provide an extension of correlation dynamics on the two-body level. The additional interaction terms are discussed in the context of time-dependent G-matrix theory and NQCD and studied numerically by one-dimensional calculations for colliding finite fermion systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288464
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A quantal toy model for heavy-ion collisions (1987)
    Springer
    The European physical journal 326 (1987), S. 21-31 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01294567
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  • 4
    Electronic Resource
    Electronic Resource
    Microscopic investigations of pion production in heavy-ion collisions (1987)
    Springer
    The European physical journal 326 (1987), S. 97-106 
    Details
    ISSN: 1434-601X
    Keywords: 25.70−z ; 25.90+k ; 13.75 Gx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Production mechanisms for subthreshold pions in nucleus-nucleus collisions are studied on a microscopic level. The non-relativistic expansion of the pseudoscalar πNN-vertex provides a basis for the construction of several two-nucleon models. These are incorporated into a dynamical description of the heavy-ion collision by boosted harmonic oscillators that adopts essential features from TDHF. The approach allows for a separate analysis of the various production processes and the influence of the collision dynamics on the total pion yield. Results are presented for the system16O +16O at laboratory energies of 40 and 80 MeV per nucleon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294576
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamical aspects of intermediate-energy nucleus-nucleus collisions (1988)
    Springer
    The European physical journal 329 (1988), S. 487-495 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.-i ; 25.70.-z ; 25.80.Ls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The production of pions in intermediate energy nucleus-nucleus collisions by incoherent nucleon-nucleon collisions is studied within a microscopic quantal phase-space approach. Employing free production rates for the elementary processN+N → π+X experimental data for inclusive pion yields are approximately reproduced from 20–150 MeV/u within the first collision approximation. These results indicate that cooperative phenomena — apart from the time-dependent mean field — seem to play a minor role for energetic particle production even at very low bombarding energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294353
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamical aspects of intermediate-energy nucleus-nucleus collisions (1987)
    Springer
    The European physical journal 327 (1987), S. 447-460 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01289571
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  • 7
    Electronic Resource
    Electronic Resource
    Dynamical aspects of intermediate-energy nucleus-nucleus collisions (1987)
    Springer
    The European physical journal 327 (1987), S. 87-100 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01295254
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  • 8
    Electronic Resource
    Electronic Resource
    Towards selfconsistent relativistic transport theories (1990)
    Springer
    The European physical journal 337 (1990), S. 1-10 
    Details
    ISSN: 1434-601X
    Keywords: 05.60.+w ; 11.10.Qr ; 24.10.Cn ; 25.70.-z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an extension of relativistic mean-field theories within the framework of quantum correlation dynamics starting from an effective hadronic Lagrangian density with minimal coupling between baryons and mesons. When neglecting retardation for the meson fields the conventional meson-exchange picture is obtained for the baryon-baryon interaction. The resulting equations of motion for the baryonic one-body density matrix and two-body correlation spinor matrix provide a nonperturbative framework for the description of relativistic heavy-ion collisions. Adopting semiclassical limits for the Wigner transform of the one-body density matrix a covariant transport equation is derived in the limit of time-dependent Dirac-Brueckner theory. It describes the mean-field dynamics including momentum-dependent potentials as well as in-medium nucleon-nucleon collisions on the basis of the same meson fields without double counting of interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283931
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Correlation dynamics of finite fermion systems (1990)
    Springer
    The European physical journal 337 (1990), S. 175-183 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.Cn ; 25.70.−z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The dynamical description of strongly interacting finite Fermi systems is based on coupled equations of motion for the one-body density matrixρ(11′) and the two-body correlation functionc 2(12, 1′2′) as obtained from the density-matrix hierarchy. The truncation schemes considered exceed the conventional Brueckner-Hartree-Fock scheme and also apply for nonstationary problems. In the limit of slow processes in time the equation of motion for the two-body correlation functionc 2 can be integrated in time and closed expressions can be given for the dynamical evolution ofρ(11′). When performing a Wigner transformation and adopting semiclassical limits this gives a transport equation of the Uehling-Uhlenbeck type for the one-body phase-space distributionf(x,p;t). Furthermore, in the small amplitude limit, we obtain a set of coupled equations for particle-hole (p-h),2p-2p, 2h-2h, 2p-2h, 1p-3h, 1h-3p amplitudes beyond the level of second RPA which provide a genuine basis for the description of giant resonances and their damping width.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294289
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamical aspects of intermediate-energy nucleus-nucleus collisions (1988)
    Springer
    The European physical journal 329 (1988), S. 471-485 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.-i ; 25.70.-z ; 25.70.Jj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The emission of nucleons in central collisions of mass symmetric and asymmetric systems in the intermediate energy regime is investigated within a quantal phase-space approach including mean field as well as two-body collision dynamics. The very energetic tails of the particle spectra are found to originate from high momentum components of the nuclear wave function as well as from successive two-body scattering. Furthermore, the angular distribution of energetic light particles for mass symmetric systems turns out to depend on the effective nucleon-nucleon cross section in the nuclear medium and might be used to determine this quantity experimentally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294352
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    Paper (German National Licenses)
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