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Do we have signals of neutron rich fireballs?. Experimental data. Fopi data [Poggi et al., Nucl. Phys. A586, 755 (1995)] Au+Au Particle 100MeV/u 150 MeV/u 250MeV/u p 49 65 87 d 57 79 108 t 62 82 124 3 He 85 101 147
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Experimental data • Fopi data [Poggi et al., Nucl. Phys. A586, 755 (1995)] • Au+Au • Particle 100MeV/u 150 MeV/u 250MeV/u • p 49 65 87 • d 57 79 108 • t 62 82 124 • 3He 85 101 147 • 4He 59 77 136 • Indra data:129Xe + 119Sn @ 50 MeV/u, DE(3He-t)=18 MeV • EOS data: Au+Au @ 250 MeV/u, DE(3He-t)=30 MeV
Description of the decay[Petrovici et al., Phys. Rev. Lett. 74, 5001 (1995)] Radial Flow Model [Bondorf, Garpman, Zimanyi, Nucl. Phys. A296, 320 (1978)] - break-up time tb - break-up density rb - thermal energy Et - collective flow Ec + Microcanonical Multifragmentation Model [Raduta, Raduta, Phys. Rev. C 55, 1344 (1997)] - primary and asympototic isotopic yields - kinetic energy spectra
Central Au+Au @ 250 MeV/u • Input parameters for RFM a=3 n=2.5 bt0=0.3
Radial isospin distribution Particle Kmed bk. (MeV) Kmed as.(MeV) Kmed Exp (MeV) p 86.8592 84.0783 87 d 114.101 111.633 108 t 133.705 129.654 124 3he 156.679 149.158 147 4he 179.619 157.082 136
Conclusions and next studies • The “abnormal” difference of the 3He and t kinetic energies was explained assuming a radial isospin distribution • What to do next? • -central Au+Au collisions at • 100 • 150 • 400 MeV/nucleon bombarding energy • -comparison with the predictions of dynamical models