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Öğe Influence of angular momentum and Coulomb interaction of colliding nuclei on their multifragmentation(AMER PHYSICAL SOC, 2015) Ergun, A.; Imal, H.; Buyukcizmeci, N.; Ogul, R.; Botvina, A. S.Theoretical calculations are performed to investigate the angular momentum and Coulomb effects on fragmentation and multifragmentation in peripheral heavy-ion collisions at Fermi energies. Inhomogeneous distributions of hot fragments in the freeze-out volume are taken into account by microcanonical Markov chain calculations within the statistical multifragmentation model. Including an angular momentum and a long-range Coulomb interaction between projectile and target residues leads to new features in the statistical fragmentation picture. In this case, one can obtain specific correlations of the sizes of emitted fragments with their velocities and an emission in the reaction plane. In addition, one may see a significant influence of these effects on isotope production both in the midrapidity and in the kinematic regions of the projectile/target. The relation of this approach to the simulations of such collisions with dynamical models is also discussed.Öğe INVESTIGATING THE ISOTOPIC EFFECTS IN NUCLEAR FRAGMENTATION(POLISH ACAD SCIENCES INST PHYSICS, 2011) Buyukcizmeci, N.; Bulut, F.; Erdogan, M.; Imal, H.; Ogul, R.; Botvina, A. S.; Mishustin, I. N.Modifications for symmetry energy coefficients of nuclear matter at freeze-out density are investigated on the basis of the Statistical Multifragmentation Model (SMM). In order to compare our predictions with MSU experimental data we consider the fragmentation of the projectiles (124)Sn and (112)Sn which were also used for the MSU experiments, and of the projectiles (124)Sn La and (107)Sn used for the ALADIN experiments. Comparing our results with the experimental data, it is confirmed that a significant reduction of the symmetry term coefficient is found necessary to reproduce the mean < N >/Z values of light fragments.Öğe Isotopic Yields and Symmetry Energy in Nuclear Multifragmentation Reactions(Iop Publishing Ltd, 2012) Buyukcizmeci, N.; Imal, H.; Ogul, R.; Botvina, A. S.; Mishustin, I. N.Isotopic yields of light intermediate mass fragments (Z 8) were studied with data from the MSU experiments for central collisions of 124 Sn + 124 Sn and 112Sn+112Sn at E/A = 50 MeV. Within the statistical multifragmentation model, microcanonical Markov-chain calculations were performed with the aim to reproduce experimental elemental and isotopic distributions. The effects of varying liquid-drop parameters of hot fragments formed inside the freeze-out volume on charge and isotopic distributions are demonstrated. It is seen that the isotopic distributions of these fragments are very sensitive to the variation of the symmetry energy of fragments. Comparing our results with the experimental data, it is seen that a significant reduction of the symmetry term coefficient leads to better reproduction of the isotopic distributions. Comparison with other statistical calculations has been made. This is in agreement with previous conclusions obtained from the interpretation of both central and peripheral heavy ion collisions.Öğe Nuclear symmetry energy in charge and isotopic distributions(IOP PUBLISHING LTD, 2013) Imal, H.; Buyukcizmeci, N.; Ogul, R.Isotopic yields of nitrogen and boron fragments from the decay of the single nucleus with A(0) = 186, Z(0) = 75 were studied on the basis of the statistical multifragmentation model, and compared with data from the MSU experiments for central collisions of Sn-124 + Sn-124 at E/A = 50 MeV. We have reconfirmed that a significant reduction of the symmetry term coefficient is necessary to reproduce the experimental isotopic distribution.Öğe Surface and symmetry energies in isoscaling for multifragmentation reactions(IOP PUBLISHING LTD, 2009) Ogul, R.; Atav, U.; Bulut, F.; Buyukcizmeci, N.; Erdogan, M.; Imal, H.; Botvina, A. S.The possibilities of modifications for symmetry and surface energy coefficients of nuclear matter at freeze-out density are investigated theoretically by means of isoscaling (isotopic scaling) on the basis of a statistical multifragmentation model. It is seen that while the isoscaling parameters as predicted by Markov chain calculations for the single sources (124)Sn and (112)Sn are very sensitive to the symmetry term, the surface energy variation slightly affects the isoscaling parameters in the multifragmentation region. The influence of these changes on the mean neutron to proton ratios of light fragments for 2 <= Z <= 10 is also shown. Comparing our results with MSU experimental data, it is confirmed that a significant reduction of the symmetry-term coefficient is found necessary to reproduce the isoscaling parameters of Z <= 8 fragments.Öğe Theoretical study of projectile fragmentation in the Sn-112+Sn-112 and Sn-124+Sn-124 reactions at 1 GeV/nucleon(AMER PHYSICAL SOC, 2015) Imal, H.; Ergun, A.; Buyukcizmeci, N.; Ogul, R.; Botvina, A. S.; Trautmann, W.We analyze the production cross sections and isotopic distributions of projectile like residues in the reactions Sn-112 + Sn-112 and Sn-124 + Sn-124 at an incident beam energy of 1 GeV/nucleon measured with the fragment separator at the GSI laboratory. Calculations within the statistical multifragmentation model for an ensemble of excited sources were performed with ensemble parameters determined previously for similar reactions at 600 MeV/nucleon. The obtained good agreement with the experiment establishes the universal properties of the excited spectator systems produced during the dynamical stage of the reaction. It is furthermore confirmed that a significant reduction of the symmetry-energy term at the freeze-out stage of reduced density and high temperature is necessary to reproduce the experimental isotope distributions. A trend of decreasing symmetry energy for large neutron-rich fragments of low excitation energy is interpreted as a nuclear-structure effect.Öğe Theoretical Study of Projectile Fragmentations in Relativistic Heavy-Ion Reactions(E D P SCIENCES, 2015) Ogul, R.; Imal, H.; Ergun, A.; Buyukcizmeci, N.; Botvina, A. S.; Trautmann, W.We have investigated and interpreted the production cross sections and isotopic distributions of projectile-like residues in the reactions (124)sn + Sn-124 and (112)sn + Sn-112 and Sn at an incident beam energy of 1 GeV/nucleon measured with the FRS fragment separator at the GSI laboratory. For the interpretation of the data, calculations within the statistical multifragmentation model (SMM) for an ensemble of excited sources were performed with ensemble parameters. The possible modification of symmetry energy parameter, in the multifragmentation region at the low density and hot freeze-out environment, is studied. It is reconfirmed that a significant reduction of the symmetry energy term is found necessary to reproduce experimental results at these conditions. We have also found a decreasing trend of the symmetry energy for large neutron-rich fragments of low excitation energy which is interpreted as a nuclear-structure effect.
