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  • 1
    Electronic Resource
    Electronic Resource
    Catapult mechanism for fast particle emission in fission and heavy ion reactions (1985)
    Springer
    The European physical journal 321 (1985), S. 343-352 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The fission process of slabs of nuclear matter is modelled in TDHF approximation by adding an initial collective velocity field to the static self-consistent solution. In dependence on its amplitude either large amplitude density oscillations are excited or fission occurs. The final disintegration of the slab proceeds on a time scale of 10−22s and is characterized by a sharp peak in the actual velocity field in the region of the “snatching” inner low density tails. A characteristic time later corresponding to the transit time of a nucleon across the fragment with mean velocity being the Fermi velocity plus twice the maximum “snatching” velocity, a low density lump correlated with a peak in the velocity field emerges in front of the fragments. We call these particles “catapult particles”. Recent experimental results possibly provide evidence for catapult neutrons in low-energy fission. We also speculate on the significance of the catapult mechanism for fast particle emission in the exit channel of heavy ion reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01493456
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A two-stage model for fast particle emission in heavy-ion collisions (1986)
    Springer
    The European physical journal 323 (1986), S. 315-329 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.Gh ; 25.70.Ji ; 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using Bertsch's TDHF-motivated trajectory model we combine two physically distinct approaches to describe fast particle emission. In the early stage we calculate particle emission in the spirit of the Fermi-jet mechanism. In the later stage, after neck formation, particles are assumed to be emitted from a rapidly expanding hot zone of appreciably large initial dimension, which is strongly anisotropic in momentum space. We calculate absolute double-differential cross sections for preequilibrium neutron emission and obtain a remarkable agreement with experimental data without introducing free parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283790
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Are promptly emitted particles really seen in TDHF? (1984)
    Springer
    The European physical journal 318 (1984), S. 87-95 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A systematic study of numerical stability of the emission of fast low density nucleonic jets in one-dimensional slab collisions is performed for different projectile-target combinations in a wide range of incident energies using a finite differences scheme. Spurious jets are shown to be connected with either a too large grid-point spacing or with a too small numerical box. The real jet which appears only for sufficiently high accuracy nearly linearly increases with increasing incident energy. The number of nucleons in the jet decreases much faster than linearly with decreasing slab thickness. Comparison with other predictions of fast-particle emission in more realistic TDHF studies is made. It is found that some contradictorily results of those investigations originate from insufficient numerical stability. The coupling of the intrinsic Fermi motion to the relative motion in a TDHF evolution is established to be very weak so that the Fermi-jet mechanism cannot be responsible for most of the energetic nucleons observed in experiment. The transition to fragmentation is investigated in connection with particle emission at high incident energies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02117218
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  • 4
    Electronic Resource
    Electronic Resource
    One-body dynamics modified by collective fluctuations (1988)
    Springer
    The European physical journal 331 (1988), S. 43-51 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.Cn ; 24.60 ; 25.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We show how the fluctuating part of the residual coupling between collective and intrinsic motion of a dissipative heavy-ion collision induces correlations in either subspace. They lead in general to a transport equation for the collective motion, and to a new term in the equation for the one-body density which describes collisions with the collective fluctuations. The resulting redistribution of the single-particle occupation numbers ρα and the evolution of the fluctuations are coupled with each other due to the dependence of the transition rates in the master equation on the fluctuations, and of the transport coefficients on ρα. Considering the special case of a long contact phase, we find the fluctuations to be most effective, with respect to a randomization of ρα, within a certain critical region where they pass from stable to unstable behaviour. Estimates are made for the corresponding relaxation times employing a schematic model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289429
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  • 5
    Electronic Resource
    Electronic Resource
    Correlations between preequilibrium particles and fission fragments? (1990)
    Springer
    The European physical journal 335 (1990), S. 473-474 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By combining an exciton-model description of preequilibrium particle emission out of a fissioning system with a diffusion model for the fission dynamics it is conjectured that in induced fission there might be dynamical correlations of preequilibrium particles and fission fragments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290196
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    Paper (German National Licenses)
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