Charged Particle Production in Proton-, Deuteron-, Oxygen- and Sulphur-Nucleus Collisions at 200 GeV per Nucleon

The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum bias proton-nucleus and deuteron-gold interactions, as well as central oxygen-gold and sulphur-nucleus collisions at 200 GeV per nucleon. The rapidity density of net protons at midrapidity in central nucleus-nucleus collisions increases both with target mass for sulphur projectiles and with the projectile mass for a gold target. The shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar. The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra of net protons for all reactions can be described by a thermal distribution with `temperatures' between 145 +- 11 MeV (p+S interactions) and 244 +- 43 MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system. The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.Comment: 47 pages, submitted to Z. Phys.

Experimental Study of the Shortest Reset Word of Random Automata

In this paper we describe an approach to finding the shortest reset word of a finite synchronizing automaton by using a SAT solver. We use this approach to perform an experimental study of the length of the shortest reset word of a finite synchronizing automaton. The largest automata we considered had 100 states. The results of the experiments allow us to formulate a hypothesis that the length of the shortest reset word of a random finite automaton with $n$ states and 2 input letters with high probability is sublinear with respect to $n$ and can be estimated as $1.95 n^{0.55}.

Event-by-event fluctuations of average transverse momentum in central Pb+Pb collisions at 158 GeV per nucleon

We present first data on event-by-event fluctuations in the average transverse momentum of charged particles produced in Pb+Pb collisions at the CERN SPS. This measurement provides previously unavailable information allowing sensitive tests of microscopic and thermodynamic collision models and to search for fluctuations expected to occur in the vicinity of the predicted QCD phase transition. We find that the observed variance of the event-by-event average transverse momentum is consistent with independent particle production modified by the known two-particle correlations due to quantum statistics and final state interactions and folded with the resolution of the NA49 apparatus. For two specific models of non-statistical fluctuations in transverse momentum limits are derived in terms of fluctuation amplitude. We show that a significant part of the parameter space for a model of isospin fluctuations predicted as a consequence of chiral symmetry restoration in a non-equilibrium scenario is excluded by our measurement.Comment: 6 pages, 2 figures, submitted to Phys. Lett.

Hadronic Expansion Dynamics in Central Pb+Pb Collisions at 158 GeV per Nucleon

Two-particle correlation functions of negative hadrons over wide phase space, and transverse mass spectra of negative hadrons and deuterons near mid-rapidity have been measured in central Pb+Pb collisions at 158 GeV per nucleon by the NA49 experiment at the CERN SPS. A novel Coulomb correction procedure for the negative two-particle correlations is employed making use of the measured oppositely charged particle correlation. Within an expanding source scenario these results are used to extract the dynamic characteristics of the hadronic source, resolving the ambiguities between the temperature and transverse expansion velocity of the source, that are unavoidable when single and two particle spectra are analysed separately. The source shape, the total duration of the source expansion, the duration of particle emission, the freeze-out temperature and the longitudinal and transverse expansion velocities are deduced

The NA49 large acceptance hadron detector

The NA49 detector is a wide acceptance spectrometer for the study of hadron production in p+p, p+A, and A+A collisions at the CERN SPS. The main components are 4 large volume TPCs for tracking and particle identification via $dE/dx$. TOF scintillator arrays complement particle identification. Calorimeters for transverse energy determination and triggering, a detector for centrality selection in p+A collisions, and beam definition detectors complete the set-up. A description of all detector components is given with emphasis on new technical realizations. Performance and operational experience are discussed in particular with respect to the high track density environment of central Pb+Pb collisions

NA49 Results on Single Particle and Correlation Measurements in Central Pb+Pb Collisions

Single-particle spectra and two-particle correlation functions measured by the NA49 collaboration in central Pb+Pb collisions at 158 GeV/nucleon are presented. These measurements are used to study the kinetic and chemical freeze-out conditions in heavy ion collisions. We conclude that large baryon stopping, high baryon density and strong transverse radial flow are achieved in central Pb+Pb collisions at the SPS.Single-particle spectra and two-particle correlation functions measured by the NA49 collaboration in central Pb+Pb collisions at 158 GeV/nucleon are presented. These measurements are used to study the kinetic and chemical freeze-out conditions in heavy ion collisions. We conclude that large baryon stopping, high baryon density and strong transverse radial flow are achieved in central Pb+Pb collisions at the SPS

Xi and Xi-bar Production in 158 GeV/Nucleon Pb+Pb Collisions

We report measurements of Xi and Xi-bar hyperon absolute yields as a function of rapidity in 158 GeV/c Pb+Pb collisions. At midrapidity, dN/dy = 2.29 +/- 0.12 for Xi, and 0.52 +/- 0.05 for Xi-bar, leading to the ratio of Xi-bar/Xi = 0.23 +/- 0.03. Inverse slope parameters fitted to the measured transverse mass spectra are of the order of 300 MeV near mid-rapidity. The estimated total yield of Xi particles in Pb+Pb central interactions amounts to 7.4 +/- 1.0 per collision. Comparison to Xi production in properly scaled p+p reactions at the same energy reveals a dramatic enhancement (about one order of magnitude) of Xi production in Pb+Pb central collisions over elementary hadron interactions.Comment: 15 page

Charged particle spectra in central S+S collisions at 200 GeV/c per nucleon

The transverse momentum and rapidity distributions of negative hadrons and participant protons have been measured for central 32S+ 32S collisions at plab=200 GeV/c per nucleon. The proton mean rapidity shift ~1.6 and mean transverse momentum ~0.6 GeV/c are much higher than in pp or peripheral AA collisions and indicate an increase in the nuclear stopping power. All pT spectra exhibit similar source temperatures. Including previous results for K0s Lambda , and Lambda -bar, we account for all important contributions to particle production.Authors: Bächler, J.; Bartke, J.; Bialkowska, H.; Bock, R.; Brockmann, R.; Buncic, P.; Chase, S. I.; Derado, I.; Eckardt, V.; Eschke, J.; Ferenc, D.; Fleischmann, B.; Foka, P.; Fuchs, M.; Gazdzicki, M.; Gladysz, E.; Harris, J. W.; Heck, W.; Hoffmann, M.; Jacobs, P. M.; Kabana, S.; Kadija, K.; Keidel, R.; Kosiec, J.; Kowalski, M.; Kühmichel, A.; Lahanas, M.; Lee, J. Y.; Ljubicic, A.; Margetis, S.; Morse, R.; Nappi, E.; Odyniec, G.; Paic, G.; Panagiotu, A. D.; Petridis, A.; Piper, A.; Posa, F.; Poskanzer, A. M.; Pugh, H. G.; Pühlhofer, F.; Rai, G.; Rauch, W.; Renfordt, R.; Röhrich, D.; Roland, G.; Rothard, H.; Runge, K.; Sandoval, A.; Schambach, J. J.; Schmitz, N.; Schmoetten, E.; Schneider, I.; Seyboth, P.; Seyerlein, J.; Skrzypczak, E.; Stefanski, P.; Stock, R.; Ströbele, H.; Teitelbaum, L.; Tincknell, M. L.; Tonse, S.; Vasileiadis, G.; Vesztergombi, G.; Vranic, D.; Wenig, S

Transverse momentum dependence of Bose-Einstein correlations in 200-A/GeV/c S + A collisions

The NA35 experiment has collected a high statistics set of momentum analyzed negative hadrons near and forward of midrapidity for central collisions of 200A GeV/c 32S+S, Cu, Ag, and Au. Using momentum space correlations to study the size of the source of particle production, the transverse source radii are found to decrease by ~40% at midrapidity and ~20% at forward rapidity while the longitudinal radius RL is found to decrease by ~50% as pT increases over the interval 50<pT<600 MeV/c. Calculations using a microscopic phase space approach (relativistic quantum molecular dynamics) reproduce the observed trends of the data. PACS: 25.75.+rAutoren: Th. Alber9, J. Bächler6, J. Bartke4, H. Bialkowska11, M. A. Bloomer3, R. Bock5, W. J. Braithwaite12, D. Brinkmann6, R. Brockmann5, P. Buncic5, P. Chan12, P. B. Cramer12, J. G. Cramer12, I. Derado9, V. Eckardt9, J. Eschke6, C. Favuzzi2, D. Ferenc6,13, B. Fleischmann5, P. Foka5, P. Freund9, M. Fuchs6, M. Gazdzicki6, E. Gladysz4, J. W. Harris3, M. Hoffman7, P. Jacobs3, S. Kabana6, K. Kadija9,13, J. Kosiec10, M. Kowalski4, A. Kühmichel6, M. Lahanas6, J. Y. Lee6, A. Ljubicic, Jr.13, S. Margetis3, J. T. Mitchell3, R. J. Morse3, E. Nappi2, G. Odyniec3, G. Paic13, A. D. Panagiotou1, A. Petridis1,9, A. Piper8, F. Posa2, A. M. Poskanzer3, F. Pühlhofer8, W. Rauch9, R. Renfordt6, W. Retyk10, D. Röhrich6, G. Roland6, H. Rothard6, K. Runge7, A. Sandoval5, J. Schambach3, N. Schmitz9, E. Schmoetten7, I. Schneider6, P. Seyboth9, J. Seyerlein9, E. Skrzypczak11, P. Spinelli2, P. Stefansky4, R. Stock6, H. Ströbele6, T. A. Trainor12, G. Vasileiadis1, M. Vassiliou1,9, D. Vranic13, S. Wenig6, and B. Wosiek4