Entropy production in the Au + Au reaction between 150 and 800 A MeV

C. Kuhn (1) , J. Konopka (1) , J.P. Coffin (1) , C. Cerruti (1) , P. Fintz (1) , G. Guillaume (1) , A. Houari (1) , F. Jundt (1) , C. Maguire (1) , F. Rami (1) , R. Tezkratt (1) , P. Wagner (1) , Z. Basrak , R.C. Caplar , N. Cindro , S. Hoelbling , J-P. Alard (2) , N. Bastid (2) , L. Berger (2) , S. Boussange (2) , I.M. Belayev , T. Blaich , A. Buta , R. Dona , P. Dupieux (2) , J. Ereo , Z.G. Fan , Z. Fodor , R. Ferifelder , L. Fraysse (2) , S. Frolov , A. Gobbi , Y. Grigorian , N. Herrmann , K.D. Hildenbrand , S.C. Jeong , M. Jorio (2) , J. Kecskemeti , P. Koncz , Y. Korchagin , R. Kotte , M. Kraemer , I. Legrand , A. A. Lebedev , V. Manko , T. Matulewicz , G. Mgebrishvili , J. Moesner , J. Moisa , Gerard Montarou (2) , I. Montbel (2) , W. Neubert , D. Pelte , M. Petrovici , S. Ramillien (2) , W. Reisdorf , A. Sadchikov , D. Schuell , Z. Seres , B. Sikora , V. Simion , S. Smolyankin , U. Sodan , K.M. Teh , M. Trzaska , M.A. Vasiliev , J.P. Wessels , T. Wienold , Z. Wilhelmi , D. Wohlfarth , A.V. Zhilin

1 IReS - Institut de Recherches Subatomiques
2 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand

The entropy per nucleon (S/A) has been extracted for the Au [(150—800)A MeV] + Au reaction by using the phase I setup of the 4 pi facility at GSI, Darmstadt. The entropy has been obtained from the comparison of various observables characterizing the dM/dZ fragment multiplicity distributions, extending up to Z~15, with those calculated with the quantum statistical model. It is the first time that S/A values are determined by considering the full ensemble of charged products detected in the reaction. Consistent values of S/A are found from different methods. These entropy values are shown to be fairly independent of the volume of the ``participant'' region considered. They are somewhat lower than those extracted in earlier works but are in good agreement with hydrodynamic calculations and suggest a low viscosity for the hot and dense nuclear matter.

Domaines: Physique des Hautes Energies - Expérience [hep-ex]

C. Kuhn, J. Konopka, J.P. Coffin, C. Cerruti, P. Fintz, et al.. Entropy production in the Au + Au reaction between 150 and 800 A MeV. Physical Review C, 1993, 48, pp.1232-1245. ⟨in2p3-00001872⟩