Onset of nuclear matter expansion in Au+Au collisions

Crochet, P.; Rami, F.; Gobbi, A.; Donà, R.; Coffin, J. P.; Fintz, P.; Guillaume, G.; Jundt, F.; Kuhn, C.; Roy, C.; Schauenburg, B. de; Tizniti, L.; Wagner, P.; Alard, J. P.; Amouroux, V.; Andronic, A.; Basrak, Z.; Bastid, N.; Belyaev, I.; Best, D.; Biegansky, J.; Buta, A.; Caplar, R.; Cindro, N.; Dupieux, P.; Delalija, M.; Fan, Z. G.; Fodor, Z.; Fraysse, L.; Freifelder, R. P.; Herrmann, N.; Hildenbrand, K. D.; Hong, B.; Jeong, S. C.; Kecskemeti, J.; Kirejczyk, M.; Koncz, P.; Korolija, M.; Kotte, R.; Lebedev, A.; Leifels, Y.; Manko, V.; Moisa, D.; Mösner, J.; Neubert, W.; Pelte, D.; Petrovici, M.; Pinkenburg, C.; Pras, P.; Ramillien, V.; Reisdorf, W.; Ritman, J. L.; Sadchikov, A. G.; Schüll, D.; Seres, Z.; Sikora, B.; Simion, V.; Siwek-Wilczyska, K.; Sodan, U.; Teh, K. M.; Trzaska, M.; Vasiliev, M.; Wang, G. S.; Wessels, J. P.; Wienold, T.; Wisniewski, K.; Wohlfarth, D.; Zhilin, A.

Onset of nuclear matter expansion in Au+Au collisions

Crochet, P.; Rami, F.; Gobbi, A.; Donà, R.; Coffin, J. P.; Fintz, P.; Guillaume, G.; Jundt, F.; Kuhn, C.; Roy, C.; de Schauenburg, B.; Tizniti, L.; Wagner, P.; Alard, J. P.; Amouroux, V.; Andronic, A.; Basrak, Z.; Bastid, N.; Belyaev, I.; Best, D.; Biegansky, J.; Buta, A.; Caplar, R.; Cindro, N.; Dupieux, P.; Delalija, M.; Fan, Z. G.; Fodor, Z.; Fraysse, L.; Freifelder, R. P.; Herrmann, N.; Hildenbrand, K. D.; Hong, B.; Jeong, S. C.; Kecskemeti, J.; Kirejczyk, M.; Koncz, P.; Korolija, M.; Kotte, R.; Lebedev, A.; Leifels, Y.; Manko, V.; Moisa, D.; Mösner, J.; Neubert, W.; Pelte, D.; Petrovici, M.; Pinkenburg, C.; Pras, P.; Ramillien, V.; Reisdorf, W.; Ritman, J. L.; Sadchikov, A. G.; Schüll, D.; Seres, Z.; Sikora, B.; Simion, V.; Siwek-Wilczyska, K.; Sodan, U.; Teh, K. M.; Trzaska, M.; Vasiliev, M.; Wang, G. S.; Wessels, J. P.; Wienold, T.; Wisniewski, K.; Wohlfarth, D.; Zhilin, A.

Using the FOPI detector at GSI Darmstadt, excitation functions of collective flow components were measured for
the Au+Au system, in the reaction plane and out of this plane, at seven incident energies ranging from 100A MeV
to 800A MeV. The threshold energies, corresponding to the onset of sideward-flow (balance energy) and
squeeze-out effect (transition energy), are extracted from extrapolations of these excitation functions toward
lower beam energies for charged products with Z>= 2. The transition energy is found to be larger than the balance
energy. The impact parameter dependence of both balance and transition energies, when extrapolated to central
collisions, suggests comparable although slightly higher values than the threshold energy for the radial flow. The
relevant parameter seems to be the energy deposited into the system in order to overcome the attractive nuclear
forces.

Keywords: Heavy ion collisions; Nuclear matter expansion; Sideward-flow; Squeeze-out; Radial flow; Balance energy; Transition energy

Nuclear Physics A 624(4) (1997) 755-772

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