Tübingen 2003 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 6: Physik mit schweren Ionen I

HK 6.11: Vortrag

Montag, 17. März 2003, 18:45–19:00, E

Directional Correlation Functions in Fragment Relative Velocity for Source Shape Determinations — •Arnaud Le Févre and Carsten Schwarz — GSI Darmstadt, Planckstr. 1, D-64291, Darmstadt

Non-isotropic effects measured with INDRA at GSI in central collisions of ¹²⁹Xe + ^natSn at 50 A MeV and ¹⁹⁷Au + ¹⁹⁷Au at 60, 80 and 100 A MeV incident energies have been observed. In all reactions, the observed anisotropy of the fragment distributions in size and mean kinetic energy indicate an incomplete shape relaxation of the multifragmenting source. Within the Berlin microcanonical multifragmentation model (MMMC) extended to a non-spherical source [1], this anisotropy can be understood as the consequence of the statistical multifragmentation of a prolate expanding source aligned along the beam direction.

In order to improve the shape characterization of the source, correlation functions between fragments have been constructed from the projected relative velocities. Their sensitivity to various properties of the source has been tested with the MMMC model. The application to the experimental data confirms the spatial elongations of the sources. The influence of the Coulomb interaction and of the collective flow on the shape sensitivity of the method is also discussed.

[1] A. Le Févre, M. Ploszajczak and V.D. Toneev, Phys. Rev. C 60, 051602 (1999).