Abstract. -Interactions induced by 200 GeV per nucleon 32 S ions on heavy targets were selected by the HELIOS calorimeters and studied in nuclear emulsions. Global observables, such a s c harged particle multiplicity and transverse energy, w ere determined event-by-event. Multiplicity and transverse energy were measured as a function of the pseudorapidity o v er the large acceptance of the present experiment (0.6 5:5). A comparison of the experimental data with those provided by the event generators FRITIOF and VENUS shows remarkable dierences both in the target spectator region and in the participant region. An attempt is made to interpret these discrepancies in terms of plausible mechanisms, like baryon-pair production or rescattering.PACS 25.75 -Relativistic heavy-ion nuclear reactions. 1 1 -I n troduction.In the search for a transition from ordinary hadron matter to a deconned chiral-symmetric quark-gluon plasma (QGP), ultra-relativistic heavy-ion collisions have been extensively studied in the last few years [1]. The initial experimental activity, successfully dealing with huge hadronic showers, demonstrated that a high enough energy density, a prerequisite for deconnement, is attainable in central collisions. However signatures of a phase transition, previously anticipated as unambiguous, such a s J / suppression or strangeness enhancement, indeed observed, were put in question, revised and somehow incorporated in less exotic schemes [2]. On the other hand, both QCD lattice calculations dening the plasma phase and rst attempts to put forward a quark-gluon transport theory progressed slowly [3][4][5].Whereas experiments with beams of much heavier ions, now collecting data both at CERN and at BNL, will probably clarify at least some of the many open questions, it is worth comparing the available data with calculations based on conventional physics. In fact, at present, any mismatch b e t w een data and predictions could hardly be claimed as an unambiguous signal of a phase transition, but just shows that complex beam-target interactions cannot be treated as a superposition of independent n ucleon-nucleon collisions. At least, more realistic models of conventional physics should be attempted, taking benet from the amount and quality o f t h e a v ailable data.In this paper we present the analysis of a sample of interactions induced by 200 GeV per nucleon 32 S ions, selected by transverse energy, E T , and studied in nuclear emulsions. The accurate measurement on each e v ent o f b o t h c harged particle multiplicity and transverse energy is a unique feature of the present experiment. This work considerably improves our previous results [6], in particular due to the increased statistics and to the wider pseudorapidity range, now spanning from the target fragmentation region up to the projectile fragmentation region.2 -Experimental procedure.Nuclear emulsion stacks were exposed to a 200 GeV per nucleon 32 S beam in the target region of the HELIOS (High-Energy Lepton and IOn Spectrometer) apparatus at CERN [7,8...