Idea Observation BUU calculations 124 Sn 124 Sn

Idea Observation BUU calculations : 124 Sn +124 Sn Tlab= 800 Me. V/u b = 5 fm L. Shi, P. Danielewicz, R. Lacey, PRC 64 (2001) T. Enqvist et al. NPA 658(1999)47 WCI 3 Texas 2005

Experiment at the Fragment Separator Inverse kinematics: (36 m) From To. F: /∆ ≈ 400 A/∆A ≈ 400 Once mass and charge are identified (A, Z are integer numbers) the velocity is calculated from B => very precise determination! /∆ = B /∆B ≈ 2000 WCI 3 Texas 2005

Characteristics of the data • unambiguous identification & precise longitudinal momenta • limited acceptance: ± 15 mrad, ± 1. 5% in momentum only one fragment in one reaction measured WCI 3 Texas 2005

Information with limited acceptance (op. I) § single, predominantly largest residue per reaction unambiguously identified § mid-peripheral collisions investigated § the largest fragment is correlated with impact parameter 238 U+Cu 1 AGe. V - ALADIN fission WCI 3 Texas 2005 fission excluded

Information with limited acceptance (op. II) Reconstruction of the velocity distribution: • limited momentum acceptance: Several magnetic field settings need to be combined to get complete velocity distribution 136 Xe+Pb at 1 A Ge. V 21 Ne D. Henzlova Ph. D thesis (in preparation) WCI 3 Texas 2005

Information with limited acceptance (op. III) How to distinguish fragmentation and fission? 238 U (1 A Ge. V) + Pb Fragmentation: heaviest residues fully accepted (A>90) Fission: Only forward and backward component accepted WCI 3 Texas 2005

Velocity correction for limited acceptance • Influence of limited angular acceptance on mean residue velocities is negligible (A ≥ 60) or small and correctable (25 ≤ A ≤ 60) WCI 3 Texas 2005