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  • 1
    Electronic Resource
    Electronic Resource
    On tunnelling with dissipation (1990)
    Springer
    The European physical journal 78 (1990), S. 325-332 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Tunnelling with dissipation is studied in a model describing the sub-barrier scattering of a particle coupled to an environment of oscillators. The influence functional formulation of Feynman's path integral approach is used. The appearance of advanced forces in the semiclassical treatment of the process as well as other specific features due to the interplay between tunnelling and dissipation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01307853
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  • 2
    Electronic Resource
    Electronic Resource
    Many-body Green's function theory for the magnetic reorientation of thin ferromagnetic films (2000)
    Springer
    The European physical journal 18 (2000), S. 579-594 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 75.10.Jm Quantized spin models - 75.30.Ds Spin waves - 75.70.Ak Magnetic properties of monolayers and thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The field-induced reorientation of the magnetization of ferromagnetic films is treated within the framework of many-body Green's function theory by considering all components of the magnetization. We present a new method for the calculation of expectation values in terms of the eigenvalues and eigenvectors of the equations of motion matrix for the set of Green's functions. This formulation allows a straightforward extension of the monolayer case to thin films with many layers and for arbitrary spin and moreover provides a practicable procedure for numerical computation. The model Hamiltonian includes a Heisenberg term, an external magnetic field, a second-order uniaxial single-ion anisotropy, and the magnetic dipole-dipole coupling. We utilize the Tyablikov (RPA) decoupling for the exchange interaction terms and the Anderson-Callen decoupling for the anisotropy terms. The dipole coupling is treated in the mean-field approximation, a procedure which we demonstrate to be a sufficiently good approximation for realistic coupling strengths. We apply the new method to monolayers with spin and to multilayer systems with S=1. We compare some of our results to those where mean-field theory (MFT) is applied to all interactions, pointing out some significant differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510070005
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  • 3
    Electronic Resource
    Electronic Resource
    Many-body Green's function theory for thin ferromagnetic anisotropic Heisenberg films: treatment of the exchange anisotropy (2003)
    Springer
    The European physical journal 32 (2003), S. 445-455 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 75.10.Jm Quantized spin models – 75.30.Ds Spin waves – 75.70.Ak Magnetic properties of monolayers and thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The many-body Green's function theory developed in our previous work for treating the reorientation of the magnetization of thin ferromagnetic films is extended to include the exchange anisotropy. This leads to additional momentum dependencies which require some non-trivial changes in the formalism. The theory is developed for arbitrary spin values S and for multilayers. The effects of the exchange anisotropy and the single-ion anisotropy, which was treated in our earlier work, on the magnetic properties of thin ferromagnetic films are compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2003-00126-3
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  • 4
    Electronic Resource
    Electronic Resource
    Shell model theory of elastic scattering of nucleons by deformed nuclei (1973)
    Springer
    The European physical journal 258 (1973), S. 1-11 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The escape width originating from a collective rotational state as a doorway state is calculated in the framework of the shell model theory of nuclear reactions. The rotational states are constructed by Yoccoz-Peierls angular momentum projection from deformed intrinsic states which are described by BCS wave functions. For some rare earth nuclei it is shown that there result escape widths of the order of magnitude of 20–100 keV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01392703
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  • 5
    Electronic Resource
    Electronic Resource
    No need for a new type of strongly damped collision in the system132Xe+56Fe at energies below 7.12 MeV/u (1981)
    Springer
    The European physical journal 299 (1981), S. 369-370 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Fusion and deep inelastic cross sections for the system132Xe+56Fe within the Gross-Kalinowski friction model are in good agreement with radiochemical measurements and in contradiction to counter experiment data. This casts doubts on the latter and the need for a new damping mechanism in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01441282
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  • 6
    Electronic Resource
    Electronic Resource
    Proton transfer in quasi-elastic and deep-inelastic reactions in the systems86Kr on88Sr,90Zr and92Mo at energies close to the coulomb barrier (1982)
    Springer
    The European physical journal 307 (1982), S. 113-140 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Reaction products corresponding to the transfer of one and several protons have been measured over a large angular range for incident energies of 380 MeV and 400 MeV in reactions of86Kr with88Sr,90Zr and92Mo. For transitions with smallQ-values (total kinetic energy loss TKEL≦10 MeV) the transfer probabilities are deduced. The magnitudes and slopes of these probabilities as function of the distance of closest approach between two nuclei are discussed. The results for single proton transfer are well described by tunneling, whereas the transfer of two and more nucleons into low lying states of the final nuclei seems to be influenced by intermediate transfer steps with larger TKEL. The data give the possibility to discuss the relation between deep-inelastic and quasi-elastic processes. The deep-inelastic data are analyzed successfully by including deformations, charge transfer and statistical fluctuations into the frictional model of Gross and Kalinowski.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414827
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of the evaporation-corrected mass and charge distributions in the Ar+Mo reactions (1983)
    Springer
    The European physical journal 313 (1983), S. 19-29 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Partly and strongly damped fragments from the reactions36Ar+92Mo and40Ar+100Mo are measured atE Lab=270 MeV. The extracted mass and charge distributions are carefully corrected forγ, n, p andα particle evaporation. The resulting primary distributions are analysed with theoretical models which assume statistical neutron and proton exchange on the potential energy surface of the projectile-target system. Dynamical-deformation effects in the framework of the surface friction model are included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02115839
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  • 8
    Electronic Resource
    Electronic Resource
    Refractive scattering and the nuclear rainbow in the interaction of12, 13C with12C at 20MeV/N (1985)
    Springer
    The European physical journal 322 (1985), S. 241-261 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.−i ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The elastic and inelastic scattering and the neutron transfer have been measured for the systems12C +12C and13C +12C at 20MeV/N up to θcm= 60° with theQ3D -spectrometer. The angular distributions of the elastic scattering show an enhanced cross section at angles larger than 40°. It can be identified as refractive scattering with the clear signature of a nuclear rainbow.L-cut-off calculations show that these contributions come fromL-values which are significantly lower than the grazingL-value. The deflection function has a broad minimum in thisL-range which is typical for rainbow scattering. TheS-matrix is decomposed by a phenomenological parametrization into a refractive and a diffractive part. The interference of these amplitudes plays an important role in the rainbow enhancement. The spatial localization of the refractive scattering is deduced from the turning points of the corresponding trajectories; a localization between 2.5 fm and 4 fm is found. Semi-classical calculations with complex trajectories in the single-turning-point approximation show good agreement with the quantummechanical calculations. Refractive contributions are not observed in the inelastic scattering. This can be explained by reducing the strength of the conventional collective form factor in the internal region. In contrast to this the enhancement at large angles is seen in the one-neutron transfer channels where the refractive scattering is dominant. This is the first observation of such contributions to heavy-ion transfer reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411889
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  • 9
    Electronic Resource
    Electronic Resource
    Combining a langevin description of heavy-ion induced fission including neutron evaporation with the statistical model (1992)
    Springer
    The European physical journal 342 (1992), S. 195-198 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.Gh ; 25.70.Jj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A model is developed which combines dynamical (Langevin-) calculations with the Kramers modified statistical model in order to describe heavy-ion induced fission including neutron evaporation. In the example of the19F+181Ta collision, the energy dependence of fission probabilities, neutron multiplicities and (H.I.,xn)-cross sections is calculated and a fair agreement with the data is achieved with a reduced friction parameter ofβ=3*1021sec−1. We pay particular attention to the angular momentum dependence of the fusion-fission process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288469
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Field-induced magnetic reorientation and effective anisotropy of a ferromagnetic monolayer within spin wave theory (2000)
    Springer
    The European physical journal 13 (2000), S. 477-489 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 75.10.Jm Quantized spin models - 75.30.Ds Spin waves - 75.70.Ak Magnetic properties of monolayers and thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The reorientation of the magnetization of a ferromagnetic monolayer is calculated with the help of many-body Green's function theory. This allows, in contrast to other spin wave theories, a satisfactory calculation of magnetic properties over the entire temperature range of interest since interactions between spin waves are taken into account. A Heisenberg Hamiltonian plus a second-order uniaxial single-ion anisotropy and an external magnetic field is treated by the Tyablikov (Random Phase Approximation: RPA) decoupling of the exchange interaction term and the Anderson-Callen decoupling of the anisotropy term. The orientation of the magnetization is determined by the spin components ( ), which are calculated with the help of the spectral theorem. The knowledge of the orientation angle allows a non-perturbative determination of the temperature dependence of the effective second-order anisotropy coefficient. Results for the Green's function theory are compared with those obtained with mean-field theory (MFT). We find significant differences between these approaches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510050059
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