Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 41: Physik mit schweren Ionen IV
HK 41.2: Vortrag
Donnerstag, 20. März 2003, 14:00–14:15, E
The Isospin-Thermometer Method to Determine the Freeeze-out Temperature in Fragmentation Reactions — •D. Henzlova1, M. V. Ricciardi1, J. Benlliure2, A. S. Botvina1, T. Enqvist1, A. Kelic1, P. Napolitani1, J. Pereira2, and K.-H. Schmidt1 — 1GSI-Darmstadt, Germany — 2Univ. Santiago de Compostela, Spain
According to the two-stage model (abrasion + evaporation), the fragmentation products with increasing mass loss should reach the universal evaporation corridor. But the mean N/Z ratios calculated from the isotopic distributions measured in experiments with 238U and 208Pb beams at 1 A GeV performed at the Fragment Separator at GSI, Darmstadt, deviate from the predicted trend. These data can be reconstructed by introducing an intermediate (break-up) stage, removing thus part of the excitation energy for the splitting into several fragments. This process can be associated with the nuclear liquid-gas phase transition. Neglecting the N/Z change in the break-up stage and knowing the parameters of the evaporation model allows to deduce the length of the evaporation chain. From this, the freeze-out temperature at the end of the break-up stage can be determined.