M. V. Ricciardia, T. Enqvista,[1], J. Pereirab, J. Benlliureb, M. Bernasc, E. Casarejosb, V. Henzla, A. Kelica, J. Taiebc,[2], K.-H. Schmidta

1
Indications for the Response of the Spectators to
the Participant Blast

• M. V. Ricciardia, T. Enqvista,1, J. Pereirab,
  J. Benlliureb, M. Bernasc, E. Casarejosb, V.
  Henzla, A. Kelica, J. Taiebc,2, K.-H. Schmidta
•  
• aGSI, Planckstr. 1, 64291, Darmstadt, Germany
• bUniversity of Santiago de Compostela, 15706
  Santiago de Compostela, Spain
• cInstitut de Physique Nucléaire, 91406 Orsay
  Cedex, France
• 1 Present address University of Jyväskylä,
  40351 Jyväskylä, Finland
• 2 Present address CEA/Saclay DM2S/SERMA/LENR,
  91191 Gif/Yvette CEDEX, France

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Motivation how to learn more about the EOS
BUU calculations 124Sn 124Sn Tlab 800
MeV/u b 5 fm L. Shi, P. Danielewicz, R.
Lacey, PRC 64 (2001)
Collective flow
pattern of particles escaping from the hot and
dense participants zone depends on EOS
Kaon production
kaons contain antistrange quark gt almost no
absorption in the nuclear medium
Spectator response
Is the spectator only a passive witness or rather
a victim of violent participants ?
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The experiment at the Fragment Separator,GSI-Darm
stadt
Inverse kinematics
From ToF ??? /???? 400
(36m)
A/?A 400
Once mass and charge are identified (A, Z are
integer numbers) the velocity is calculated from
B? gt very precise evaluation!
??? /???? B?/?B? 2000
4
Velocity distributions of fragmentation residues
238UPb _at_ 1 AGeV
T.Enqvist et al. NPA658(1999)47
238UTi _at_ 1 AGeV
M.V.Ricciardi et al. PRL 90(2003)212302
5
Mean velocities of fragmentation residues
T.Enqvist et al. NPA658(1999)47 M.V.Ricciardi et
al. PRL 90(2003)212302

• Indications for the postulated response of the
  spectators to the participant blast.

In reality, spectator are the participants
victims !!!

• Precise velocity measurement of projectile
  fragments is a new tool to investigate the EOS of
  nuclear matter

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What can we learn from the victims?
Theoretical calculations (Shi, Danielewicz,
Lacey)

1. Change of the net momentum per nucleon (NM)
   depends on momentum dependence of the nuclear
   mean field (MF)
2. Dependence of NM change on stiffness of EOS very
   small

Spectator response reflects the MD properties of
the nuclear MF !!!