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Motivation Energy and time calibration R esults 4. Summary

Ternary reactions in 197 Au+ 197 Au collisions revisited. I. Skwira-Chalot, K. Siwek-Wilczyńska, J. Wilczyński (for CHIMERA Collaboration). Motivation Energy and time calibration R esults 4. Summary. Motivation. Main goal:

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Motivation Energy and time calibration R esults 4. Summary

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  1. Ternary reactions in 197Au+197Au collisions revisited I. Skwira-Chalot, K. Siwek-Wilczyńska, J. Wilczyński (for CHIMERA Collaboration) • Motivation • Energy and time calibration • Results • 4. Summary

  2. Motivation Main goal: To observe transition between two basic mechanisms of energy dissipation: one-body and two-body dissipation. Very heavy system Experiment at 10 – 20 MeV/nucleon Kazimierz, 30.09.2006

  3. Motivation Los Alamos model of fission N. Cârjan, A. Sierk, and J. R. Nix, Nucl. Phys. A 452 (1986) 381 Kazimierz, 30.09.2006

  4. Motivation • formation of 3-rd fragment instead of 2-BD 1-BD • different Ekin (relative motion) Best signatures of 1-BD  2-BD transition for ternary division of very heavy systems Kazimierz, 30.09.2006

  5. Experiment beam CsI(Tl) target Si Heavy system: Beam energy: 197Au + 197Au 15 AMeV Charged Heavy Ion Mass and Energy Resolving Array 100 lab 860 E TOF We detect fragments which stop in silicon detector. 1192 telescopes Kazimierz, 30.09.2006

  6. Energy calibration Reactions used for energy calibration Elastic scattering 12C + 197Auat 40 and 90 MeV separate 16O + 197Auat 60 and 100 MeV experiments 197Au + 197Auat 15 MeV/nucleon Inelasticscattering 197Au + 197Auat 15 MeV/nucleon Fission fragments 197Au + 12Cat 15 MeV/nucleon Kazimierz, 30.09.2006

  7. Time calibration Kinetic energy formula • M – mass • D – distance • - coefficient ns/channel t0 – „time zero” tch – time in channels • TOF calibration based on • energy spectrum of projectile-like fragments of A 197 • fission fragments from the 197Au + 12C reaction • energy spectrum of Li fragments stopped in Si detectors FIND Kazimierz, 30.09.2006

  8. Time calibration Kazimierz, 30.09.2006

  9. Forthe analysis we take information from silicon detectors in R5to R16(100 lab 860). We disregard particles with A 6. Kazimierz, 30.09.2006

  10. Selection of „binary” events We selected a class of binary events satisfying conditions: the total mass: the transversal momentum: coplanarity with beam direction: colinearity in the C.M. system: Kazimierz, 30.09.2006

  11. Results. Mass – angle distribution of binary events Kazimierz, 30.09.2006

  12. Results. Transversal vs. longitudinal velocity. Preliminary result 2005 corresponding to A Kazimierz, 30.09.2006

  13. Results Preliminary result 2005 corresponding to A Kazimierz, 30.09.2006

  14. Summary Collisions of a very heavy 197Au+197Au system at 15 AMeVwere studied in an exclusive 4 detection experiment. In the selected class of ternary events we observe clear evidence for sequential fission processes. We are going to determine the time scale of these reactions. Events when three fragments of comparable masses are formed simultaneously (massive middle fragment formation) are less intensive than in the previous preliminary analysis based on incomplete data. The study of the dominating dissipation mechanism and theoretical analysis of the 197Au+197Au reaction in terms of the QMD model of Lukasik and stochastic BNV model of Di Toro et al. are under way. Kazimierz, 30.09.2006

  15. Collaboration INFN, Laboratori Nazionali del Sud e Dipartimento di Fisica e Astronomia, Università di Catania INFN, Sezione di Catania e Dipartimento di Fisica e Astronomia, Università di Catania INFN, Sezione di Milano e Dipartimento di Fisica, Università di Milano INFN, Gruppo Collegato di Messina e Dipartimento di Fisica, Università di Messina Institute of Experimental Physics, Warsaw University, Warsaw Soltan Institute for Nuclear Studies, Świerk/Warsaw M. Smoluchowski Institute of Physics Jagiellonian University,Cracow Institute of Physics, University of Silesia, Katowice GANIL, CEA, IN2P3 - CNRS, Caen Departament of Physics, University of Ioannina, Ioannina Saha Institute Of Nuclear Physics, Kolkata Zakopane 2006

  16. Results Preliminary result 2005 corresponding to A Kazimierz, 30.09.2006

  17. 100 lab 700 100 lab 860 Kazimierz, 30.09.2006

  18. 100 lab 700 100 lab 860 Kazimierz, 30.09.2006

  19. Results. Selection of „ternary” events 100 lab 700 100 lab 860 We selected a class of ternary eventssatisfying nearly complete balance of mass numbers: Kazimierz, 30.09.2006

  20. Results. Selection of „ternary” events 100 lab 700 100 lab 860 We selected events for which Kazimierz, 30.09.2006

  21. Results Preliminary result 2005 corresponding to A Kazimierz, 30.09.2006

  22. Kazimierz, 30.09.2006

  23. Kazimierz, 30.09.2006

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