U. Kleinevoss

Publications (4)0.9 Total impact

• Source

  Available from: ArXiv

  Article: Thermal and Chemical Freeze-out in Spectator Fragmentation

  W. Trautmann, R. Bassini, M. Begemann-blaich, A Ferrero, S. Fritz, S. J. Gaff-Ejakov, C. Gross, G. Imme, I. Iori, U. Kleinevoss
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  ABSTRACT: Isotope temperatures from double ratios of hydrogen, helium, lithium, beryllium, and carbon isotopic yields, and excited-state temperatures from yield ratios of particle-unstable resonances in 4He, 5Li, and 8Be, were determined for spectator fragmentation, following collisions of 197Au with targets ranging from C to Au at incident energies of 600 and 1000 MeV per nucleon. A deviation of the isotopic from the excited-state temperatures is observed which coincides with the transition from residue formation to multi-fragment production, suggesting a chemical freeze-out prior to thermal freeze-out in bulk disintegrations.
  09/2007;
• Article: Interplay of Equilibrium and Nonequilibrium Phenomena in the Nuclear Liquid-Gas Phase Transition

  B. Zwieglinski, T. Odeh, C. Gross, C Schwarz, R. Bassini, S. Fritz, D. Gourio, I. Iori, U. Kleinevoss, G J Kunde, [......], W. F. J. Muller, C. Nociforo, B. Ocker, F. Petruzzelli, J. Pochodzalla, G. Raciti, G. Riccobene, A. Saija, W. Seidel, A. Worner
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  ABSTRACT: t, D-60486 Frankfurt, Germany e Forschungszentrum Rossendorf, D-1314 Dresden, Germany f Max-Planck-Institut fur Kernphysik, D-69117 Heidelberg, Germany g Soltan Institute for Nuclear Studies, 00-681 Warsaw, Hoza 69, Poland h NSCL, Michigan State University, East Lansing, MI 48824, USA Energy spectra of protons emitted by the target residue in Au+Au collisions at 1 GeV/u reveal two components with different slopes attributed to preequilibrium and equilibrium emission. The relative contribution of the latter decreases rapidly with excitation energy, so that its presence becomes not apparent for the highest energy bins. It is argued therefore, that equilibrium may not be reached on the gas branch of the caloric curve. The nuclear liquid-gas phase transition thus belongs to the category of nonequilibrium phase transitions for which the concepts developed in synergetics, such as self-organized criticality, provid
  08/2000;
• Article: Nonequilibrium Features of the Nuclear Liquid-Gas Phase Transition

  B. Zwieglinski, T. Odeh, C. Gross, C. Schwarz, R. Bassini, M. Begemann-Blaich, T. Blaich, H. Emling, A. Ferrero, S. Fritz, [......], A. Schuettauf, W. Seidel, V. Serfling, J. Stroth, W. Trautmann, A. Trzcinski, G. Verde, A. Woerner, H. Xi, E. Zude
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  ABSTRACT: Energy spectra of protons emitted by the target residue in Au + Au collisions at 1 GeV/u were measured for different excitation energy bins. They reveal two components with different slopes attributed to preequilibrium and equilibrium emission. The relative contribution of the latter decreases rapidly with excitation energy, so that its presence becomes not apparent for the highest energy bins. It is argued therefore, that equilibrium may not be reached on the gas branch of the caloric curve.
  Acta Physica Polonica Series B 02/1999; 30:445. · 0.90 Impact Factor
• Article: A systematic study of the nuclear caloric curve

  G. Raciti, R. Bassini, M. Begemann-Blaich, S. Fritz, S. J. Gaff, N. Giudice, C. Gross, G. Immé, I. Iori, U. Kleinevoss, [......], C. Schwarz, W. Seidel, V. Serfling, C. Sfienti, W. Trautmann, A. Trzcinski, G. Verde, A. Wörner, H. Xi, B. Zwieglinski
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  ABSTRACT: Temperature-excitation energy correlation measurements on several systems at different incident energies are discussed in the framework of the investigation on possible liquid-gas phase transition in nuclear matter. Results are compared to the presently available experimental caloric curves. Moreover theisotope and theexcited states temperatures, extracted from double ratios of isotope yields and population ratios of fragment unbound states, respectively, are compared. p ]The differences on the temperatures deduced from the two methods cannot be accounted for by the sequential feeding corrections. Instead, they seem to be related to the space-time evolution of the fragmentation process.
  Il Nuovo Cimento A 04/1998; 111(8):987-997.