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Spectator response to the participant blast in the reaction 197 Au+ 197 Au at 1 A GeV – results of the first dedicated experiment. New tool for investigating the momentum- dependent properties of nuclear matter. V. Henzl for CHARMS collaboration GSI, Planckstr. 1, 64291, Darmstadt, Germany
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Spectator response to the participant blast in the reaction 197Au+197Au at 1 A GeV – results of the first dedicated experiment New tool for investigating the momentum- dependent properties of nuclear matter. • V. Henzl for CHARMS collaboration • GSI, Planckstr. 1, 64291, Darmstadt, Germany • (on leave from NPI Rez, Czech Republic)
Idea BUU calculations : 124Sn +124Sn Tlab= 800 MeV/u b = 5 fm L. Shi, P. Danielewicz, R. Lacey, PRC 64 (2001) T.Enqvist et al. NPA658(1999)47 M.V.Ricciardi et al.PRL 90(2003)212302 Observation Fission events excluded !!! Vlad Henzl for CHARMS
Idea BUU calculations : 124Sn +124Sn Tlab= 800 MeV/u b = 5 fm L. Shi, P. Danielewicz, R. Lacey, PRC 64 (2001) Observation T.Enqvist et al. NPA658(1999)47 BUU by V.H. Vlad Henzl for CHARMS
Experiment at the Fragment Separator Inverse kinematics: From ToF: /∆ ≈ 400 A/∆A ≈ 400 (36m) Once mass and charge are identified (A, Z are integer numbers) thevelocity is calculated from B => veryprecise determination! /∆ = B/∆B≈ 2000 Vlad Henzl for CHARMS
Characteristics of the data Au+Au@1 A GeV Pb+p@1 A GeV • unambiguous identification & precise longitudinal momenta • limited acceptance: ±15mrad, ±1.5% in momentum only one fragment in one reaction measured Vlad Henzl for CHARMS
Characteristics of velocity distributions 136Xe+natPb @ 1 A GeV (D.Henzlova) 197Au+197Au @ 1 A GeV (V.H.) • limited momentum acceptance: Several magnetic field settings need to be combined to get complete velocity distribution Possible discrimination of fragmentation and fission Vlad Henzl for CHARMS
Information from 4π experiments 238U+Cu 1AGeV - ALADIN fission fission excluded • single, predominantly largest residue per reaction unambiguously identified at FRS • mid-peripheral collisions investigated • the largest fragment is correlated with impact parameter (for Zmax>30 ~ Amax>65) Aladin data: Au+Au@400, 600, 800, 1000 AMeV Vlad Henzl for CHARMS
New experimental data, new simulations • reacceleration observed for Ares≤ 85 • BUU calculations with MD mean fields qualitatively agree with experiment (no sensitivity to stiffness of EoS) • BUU calculations with static MI field are not able to describe trend of the data Vlad Henzl for CHARMS
Summary & Outlook Summary: • Spectator response to the participant blast measured in Au+Au@1AGeV, reacceleration of the fragmentation residues observed for Ares≤ 85 • only BUU with MD MF induce recovery of the fragment velocities with decreasing impact parameter, in qualitative agreement with the experiment • Spectator response is a selective tool to access MD properties of MF • further experiments needed to constrain MD properties of nuclear mean field Outlook: • 197Au+197Au @ 500 A MeV (analysis in progress) • 197Au+27Al @ 500 A MeV (analysis in progress) • 112,124Sn+112,124Sn @ 1 A GeV (2005/2006) Vlad Henzl for CHARMS