2018 Impact factor 2.481
Hadrons and Nuclei
Eur. Phys. J. A 6, 185-195

The FOPI Collaboration

On the space-time difference of proton and composite particle emission in central heavy-ion reactions at 400 A $\cdot$ MeV

R. Kotte5 - H. W. Barz5 - W. Neubert5 - C. Plettner5 - D. Wohlfarth5 - J. P. Alard3 - A. Andronic1 - R. Averbeck4 - Z. Basrak12 - N. Bastid3 - N. Bendarag3 - G. Berek2 - R. Caplar12 - N. Cindro12 - P. Crochet3 - A. Devismes4 - P. Dupieux3 - M. Dzelalija12 - M. Eskef6 - Z. Fodor2 - A. Gobbi4 - Y. Grishkin7, N. Herrmann6, K. D. Hildenbrand4, B. Hong9, J. Kecskemeti2 - Y.J. Kim9 - M. Kirejczyk11 - M. Korolija12 - M. Kowalczyk11 - T. Kress4 - R. Kutsche4 - A. Lebedev7 - K.S. Lee9 - Y. Leifels6 - V. Manko8 - H. Merlitz6, D. Moisa1 - A. Nianine8 - D. Pelte6 - M. Petrovici1 - F. Rami10 - W. Reisdorf4 - B. de Schauenburg10 - D. Schüll4 - Z. Seres2 - B. Sikora11 - K.S. Sim9 - V. Simion1 - K. Siwek-Wilczynska11 - A. Somov7 - G. Stoicea1 - M. A. Vasiliev8 - P. Wagner10 - K. Wisniewski11 - J.T. Yang9 - Y. Yushmanov8 - A. Zhilin7

1 Institute for Nuclear Physics and Engineering, Bucharest, Romania
2 Central Research Institute for Physics, Budapest, Hungary
3 Laboratoire de Physique Corpusculaire, Université Blaise Pascal, Clermont-Ferrand, France
4 Gesellschaft für Schwerionenforschung, Darmstadt, Germany
5 Forschungszentrum Rossendorf, PF 510119, 01314 Dresden, Germany, ()
6 Physikalisches Institut der Universität Heidelberg, Heidelberg, Germany
7 Institute for Experimental and Theoretical Physics, Moscow, Russia
8 Kurchatov Institute for Atomic Energy, Moscow, Russia
9 Korea University, Seoul, Korea
10 Institut de Recherches Subatomiques, IN2P3-CNRS/ULP, Strasbourg, France
11 Institute of Experimental Physics, Warsaw University, Warsaw, Poland
12 Rudjer Boskovic Institute Zagreb, Zagreb, Croatia

Received: 5 April 1999 / Revised version: 15 July 1999 Communicated by B. Povh

Small-angle correlations of pairs of nonidentical light charged particles produced in central collisions of heavy ions in the A=100 mass region at a beam energy of 400 $A\cdot$MeV are investigated with the FOPI detector system at GSI Darmstadt. The difference of longitudinal correlation functions with the relative velocity parallel and anti-parallel to the center-of-mass velocity of the pair in the central source frame is studied. This method allows extracting the apparent space-time differences of the emission of the charged particles. Comparing the correlations with results of a final-state interaction model delivers quantitative estimates of these asymmetries. Time delays as short as 1 fm/c or - alternatively - source radius differences of a few tenth fm are resolved. The strong collective expansion of the participant zone introduces not only an apparent reduction of the source radius but also a modification of the emission times. After correcting for both effects a complete sequence of the space-time emission of p, d, t, 3He, $\alpha$ particles is presented for the first time.

25.70.Pq Multifragment emission and correlations

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