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Article
Report number	nucl-ex/9908014 ; IRES-2000-03
Title	Isospin tracing : a probe of non-equilibrium in central heavy-ion collisions
Author(s)	Rami, F ; Leifels, Y ; De Schauenburg, B ; Gobbi, A ; Hong, B ; Alard, J P ; Andronic, A ; Averbeck, R ; Barret, V ; Basrak, Z ; Bastid, N ; Belyaev, I ; Bendarag, A ; Berek, G ; Caplar, R ; Cindro, N ; Crochet, Philippe ; Devismes, A ; Dupieux, P ; Dzelalija, M ; Eskef, M ; Finck, C ; Fodor, Z ; Folger, H ; Fraysse, L ; Genoux-Lubain, A ; Grigorian, Yu I ; Grishkin, Yu L ; Herrmann, N ; Hildenbrand, K D ; Kecskeméti, J ; Kim, Y J ; Koczón, P ; Kirejczyk, M ; Korolija, M ; Kotte, R ; Kowalczyk, M ; Kress, T ; Kutsche, R ; Lebedev, A ; Lee, K S ; Man'ko, V I ; Merlitz, H ; Mohren, S ; Moisa, D ; Mösner, J ; Neubert, W ; Nyanin, A ; Pelte, D ; Petrovici, M ; Pinkenburg, C H ; Plettner, C ; Reisdorf, W ; Ritman, J L ; Schüll, D ; Seres, Z ; Sikora, B ; Sim, K S ; Simion, V ; Siwek-Wilczynska, K ; Somov, A ; Stockmeier, M R ; Stoicea, G ; Vasilev, M ; Wagner, P ; Wisniewski, K ; Wohlfarth, D ; Yang, J T ; Yushmanov, I E ; Zhilin, A V
Publication	2000
Imprint	2000
In:	Phys. Rev. Lett. 84 (2000) 1120
DOI	10.1103/PhysRevLett.84.1120
Subject category	Nuclear Physics - Experiment
Abstract	Four different combinations of $^{96}_{44}$Ru and $^{96}_{40}$Zr nuclei, both as projectile and target, were investigated at the same bombarding energy of 400$A$ MeV using a $4 \pi$ detector. The degree of isospin mixing between projectile and target nucleons is mapped across a large portion of the phase space using two different isospin-tracer observables, the number of measured protons and the ${\rm t}/^{3}{\rm He}$ yield ratio. The experimental results show that the global equilibrium is not reached even in the most central collisions. Quantitative measures of stopping and mixing are extracted from the data. They are found to exhibit a quite strong sensitivity to the in-medium (n,n) cross section used in microscopic transport calculations.

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