1. Measurement of the Response of the Spectators to the Participants Blast
M. V. Ricciardia, T. Enqvista,[1], J. Pereirab, J. Benlliureb, M. Bernasc, E. Casarejosb, V. Henzla, A. Kelića, J. Taiebc,[2], K.-H. Schmidta
aGSI, Planckstr. 1, 64291, Darmstadt, Germany
bUniversity of Santiago de Compostela, Santiago de Compostela, Spain
cInstitut de Physique Nucléaire, Orsay Cedex, France
[1] Present address: University of Jyväskylä, Jyväskylä, Finland
[2] Present address: CEA/Saclay DM2S/SERMA/LENR, Gif/Yvette CEDEX, France

2. Motivation
BUU calculations : 124Sn +124Sn Tlab= 800 MeV/u b = 5 fm
L. Shi, P. Danielewicz, R. Lacey, PRC 64 (2001)
The surviving spectator is influenced by the blast of the participants
Response of the spectators is ruled by the properties of the nuclear matter (=> EOS) !!!

3. The experiment at the Fragment Separator, GSI-Darmstadt
Once mass and charge are identified (A, Z are integer numbers) the velocity is calculated from B => very precise evaluation!

4. Velocity distributions of fragmentation residues
238U+Pb (dashed line)
238U+Ti (full lines)
T.Enqvist et al. NPA658(1999)47
M.V.Ricciardi et al. submitted to PRL

5. Mean velocities of fragmentation residues
T.Enqvist et al. NPA658(1999)47
M.V.Ricciardi et al. submitted to PRL
Indications for the postulated response of the spectators to the participant blast.
Precise velocity measurement of projectile fragments is a new tool to investigate the EOS of nuclear matter

6. The epilogue: “What can we learn from the spectators?”
Theoretical calculations: (Shi, Danielewicz, Lacey)
Change of the net momentum (NM) depends on momentum dependence of the nuclear mean field (MF)
Dependence of NM change on stiffness of EOS very small
Different reaction systems => different response