Bulent Yilmaz

Publications (4)0 Total impact

• Article: Large Amplitude motion with a stochastic mean-field approach

  Denis Lacroix, Sakir Ayik, Bulent Yilmaz, Kouhei Washiyama
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  ABSTRACT: In the stochastic mean-field approach, an ensemble of initial conditions is considered to incorporate correlations beyond the mean-field. Then each starting pont is propagated separately using the Time-Dependent Hartree-Fock equation of motion. This approach provides a rather simple tool to better describe fluctuations compared to the standard TDHF. Several illustrations are presented showing that this theory can be rather effective to treat the dynamics close to a quantum phase transition. Applications to fusion and transfer reactions demonstrate the great improvement in the description of mass dispersion.
  10/2012;
• Article: Symmetry breaking and fluctuations within stochastic mean-field dynamics: importance of initial quantum fluctuations

  Denis Lacroix, Sakir Ayik, Bulent Yilmaz
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  ABSTRACT: Dynamics of spontaneous symmetry breaking and fluctuations in the Lipkin-Meshkov-Glick model are investigated in a stochastic mean-field approach. Different from the standard mean-field, in the stochastic approach, initial state fluctuations, are incorporated. In weak coupling, the approach perfectly reproduces the exact quantal dynamics. On the other hand, for increasing coupling strength, above the symmetry breaking threshold, the approach provides description of gross properties (i.e. time averaged behavior) of the exact quantal evolution.
  03/2012;
• Source

  Available from: Sakir Ayik

  Article: Stochastic Semi-Classical Description of Fusion at Near-Barrier Energies

  Sakir Ayik, Bulent Yilmaz, Denis Lacroix
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  ABSTRACT: Fusion reactions of heavy ions are investigated by employing a simple stochastic semi-classical model which includes the coupling between relative motion and low frequency collective surface modes of colliding ions similarly to the quantal coupled-channels description. The quantal effect enters into the calculation through the initial zero-point fluctuations of the surface vibrations. Good agreement with the result of coupled-channels calculations as well as data is obtained for the fusion cross sections of nickel isotopes. The internal excitations in non-fusing events as well as the fusion time are investigated. Comment: 8 pages, 8 figures, Published in Phys. Rev. C
  01/2010;
• Source

  Available from: Sakir Ayik

  Article: Quantum effects in the diffusion process to form a heavy nucleus in heavy-ion fusion reactions

  Kouhei Washiyama, Bulent Yilmaz, Sakir Ayik, Noboru Takigawa
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  ABSTRACT: We discuss quantum effects in the diffusion process which is used to describe the shape evolution from the touching configuration of fusing two nuclei to a compound nucleus. Applying the theory with quantum effects to the case where the potential field, the mass and friction parameters are adapted to realistic values of heavy-ion collisions, we show that the quantum effects play significant roles at low temperatures which are relevant to the synthesis of superheavy elements. Comment: 5 pages, 2 figures. Uses aipxfm.sty. A talk given at the FUSION06: International Conference on Reaction Mechanisms and Nuclear Structure at the Coulomb barrier, March 19-23, 2006, San Servolo, Venezia, Italy
  05/2006;