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Ströbele, Herbert ; Brockmann, Robert ; Harris, John W. ; Riess, F. ; Sanodoval, Andres ; Stock, Reinhard ; Wolf, Kevin L. ; Pugh, Howel G. ; Schroeder, Lee S. ; Renfordt, Rainer Arno Ernst ; Tittel, Klaus ; Maier, M.
An event by event analysis is carried out for all charged particles observed in central collisions of 40Ar + KCl and 40Ar + Pb at 1.808 and 0.772 GeV/nucleon, respectively. Total transverse energy is used for impact parameter selection within the central trigger condition. The central Ar + KCl reaction exhibits a forward-backward oriented momentum flux. The flux distribution of the most central Ar + Pb events is approximately isotropic in the fireball center of mass.
Stock, Reinhard ; Bock, Rudolf ; Brockman, R. ; Harris, John W. ; Sandoval, Andres ; Ströbele, Herbert ; Wolf, Kevin L. ; Pugh, Howel G. ; Schroeder, Lee S. ; Maier, M. ; Renfordt, Rainer Arno Ernst ; Dacal, Ángel ; Ortiz, Maria Esther
The negative-pion multiplicity is measured for central collisions of 40Ar with KCl at eight energies from 0.36 to 1.8 GeV/nucleon and for 4He on KCl and 40Ar on BaI2 at 977 and 772 MeV/nucleon, respectively. A systematic discrepancy with a cascade-model calculation which fits proton- and pion-nucleus cross sections but omits potential-energy effects is used to derive the energy going into bulk compression of the system. A value of the incompressibility constant of K=240 MeV is extracted in a parabolic form of the nuclear-matter equation of state.
Sandoval, Andres ; Stock, Reinhard ; Stelzer, Herbert ; Renfordt, Rainer Arno Ernst ; Harris, John W. ; Brannigan, James P. ; Geaga, Jorge V. ; Rosenberg, L. J. ; Schroeder, Lee S. ; Wolf, Kevin L.
Exclusive pi - and charged-particle production in collisions of Ar+KCl is studied at incident energies from 0.4 to 1.8 GeV/u. Complete disintegration of both nuclei is observed. The correlation between pi - and total charge multiplicity shows no islands of anomalous pion production. For constant numbers of proton participants the pi - multiplicity distributions are Poissons. For central collisions <n pi -> increases smoothly and to first order linearly with the c.m. energy. Disagreement with the firestreak model is found. Pacs numbers: 25.70.Hi, 24.10.Dp
Renfordt, Rainer Arno Ernst ; Schall, Dietmar ; Bock, Rudolf ; Brockmann, Robert ; Harris, John W. ; Sandoval, Andres ; Stock, Reinhard ; Ströbele, Herbert ; Bangert, Dietmar ; Rauch, Wolfgang ; Odyniec, Grazyna Janina ; Pugh, Howel G. ; Schroeder, Lee S.
Charged-particle exclusive data for Ar+Pb collisions at 0.772 GeV/u are analyzed in terms of collective variables for the event shapes in momentum space. Semicentral collisions lead to sidewards flow whereas nearly head-on collisions have spherical shapes in the c.m. frame, resulting from complete stopping of projectile motion. The hydrodynamical model predictions agree qualitatively with the data whereas the standard cascade model disagrees, lacking in stopping power and collective flow.
Harris, John W. ; Odyniec, Grazyna Janina ; Pugh, Howel G. ; Schroeder, Lee S. ; Tincknell, Mark L. ; Rauch, Wolfgang ; Stock, Reinhard ; Bock, Rudolf ; Brockmann, Robert ; Sandoval, Andres ; Ströbele, Herbert ; Renfordt, Rainer Arno Ernst ; Schall, Dietmar ; Bangert, Dieter ; Sullivan, John P. ; Wolf, Kevin L. ; Dacal, Ángel ; Guerra, C. ; Ortiz, Maria Esther
Danielewicz, Pawel ; Ströbele, Herbert ; Odyniec, Grazyna Janina ; Bangert, Dietmar ; Bock, Rudolf ; Brockmann, Robert ; Harris, John W. ; Pugh, Howel G. ; Rauch, Wolfgang ; Renfordt, Rainer Arno Ernst ; Sandoval, Andres ; Schall, Dietmar ; Schroeder, Lee S. ; Stock, Reinhard
Semicentral Ar+KCl, La+La, and Ar+Pb collisions at 800 MeV/nucleon were studied using a streamer chamber. The results are analyzed in the framework of the transverse momentum analysis and in terms of the average sphericity matrix. A critical examination of the analysis procedures, both experimental and theoretical, is given. New procedures are described to account for overall momentum conservation in the reaction, and to correct for azimuthal variations in the detection efficiency. Average transverse momenta per nucleon in the reaction plane are presented for deuterons emitted in the forward hemisphere, as these provide the most reliable information. A Vlasov-Uehling-Uhlenbeck calculation with a stiff equation of state gives a good fit to the momenta in the Ar+Pb reaction. Flow effects parametrized further using the sphericity tensor are found stronger than in the cascade model and consistently weaker than predicted by hydrodynamics. Parameters from the sphericity tensor exhibit a larger variation as a function of multiplicity than do the average momenta per nucleon.
Claesson, G. ; Krebs, Gary F. ; Miller, J. ; Roche, Guy ; Schroeder, Lee S. ; Beneson, Walter ; Plicht, Johannes van der ; Winfield, John S. ; Landaud, Gilbert ; Gilot, J.F. ; Hartnack, Christoph ; Stöcker, Horst
Brockmann, Robert ; Harris, John W. ; Sandoval, Andres ; Stock, Reinhard ; Ströbele, Herbert ; Odyniec, Grazyna Janina ; Pugh, Howel G. ; Schroeder, Lee S. ; Renfordt, Rainer Arno Ernst ; Schall, Dietmar ; Bangert, Dieter ; Rauch, Wolfgang ; Wolf, Kevin L.
Pion and proton production are measured to investigate thermal equilibrium in central collisions of 40Ar+KCl at 1.8 GeV/nucleon. The bulk of the pion yield is isotropic in the c.m. system, with an apparent temperature of 58±3 MeV, much lower than the 118±2 MeV of the protons. It is shown that the low pion "temperature" can be explained by the decay kinematics of delta resonances in thermal equilibrium. A (5±1)% component in the pion spectrum is, however, found to have a temperature of 110±10 MeV. The effect on the spectra of possible contributions from collective radial flow is discussed.
Beavis, Dana Richard ; Bock, Rudolf ; Brockmann, Robert ; Danielewicz, Pawel ; Fung, Sun-Yiu ; Harris, John W. ; Keane, Declan ; Liu, Y. M. ; Odyniec, Grazyna Janina ; Pugh, Howel G. ; Renfordt, Rainer Arno Ernst ; Sandoval, Andres ; Schall, Dietmar ; Schroeder, Lee S. ; Stock, Reinhard ; Ströbele, Herbert ; Vient, M. A.
The energy dependence of rapidity distributions and flow effects was studied in central Ar+Pb collisions at 400, 800, and 1800 MeV/nucleon using a streamer chamber. Rapidity distributions for proton and pions are found to have a Gaussian shape whereas those for deuterons exhibit a two-peak structure at the two higher energies. The average in-plane transverse momentum per/nucleon and per/event shows saturation of flow around 800 MeV/nucleon for this asymmetric system. The aspect ratio of the sphericity tensor is closely correlated with the flow angle. This correlation appears to be independent of beam energy. The number of participating nucleons in central collisions varies from 213 at 400 to 135 at 1800 MeV/nucleon indicating that at the lowest energy almost the entire target nucleus participates in the collision.
Adler, Clemens ; Ahammed, Zubayer ; Allgower, Chris ; Anderson, Mike ; Averichev, Georgy S. ; Balewski, Jan ; Barannikova, Olga ; Barnby, Lee Stuart ; Baudot, Jérome ; Bekele, Selemon ; Belaga, Victoria Vladimirovna ; Bellwied, Rene ; Berger, Jens ; Bichsel, Hans ; Bland, Leslie C. ; Blyth, Charles O. ; Bonner, Billy E. ; Bossingham, R. ; Boucham, Abdelkrim ; Brandin, Andrei V. ; Caines, Helen Louise ; Calderón de la Barca Sánchez, Manuel ; Cardenas, Andrés ; Carroll, J. ; Castillo Castellanos, Javier Ernesto ; Castro, M. ; Cebra, Daniel A. ; Chattopadhyay, S. ; Chen, M. L. ; Chen, Y. ; Chernenko, Sergey P. ; Cherney, Michael Gerard ; Chikanian, Alexei ; Choi, B. ; Christie, William ; Coffin, Jean Pierre ; Conin, Laurent ; Cormier, Thomas Michael ; Cramer, John G. ; Crawford, Henry J. ; DeMello, M. ; Deng, W. S. ; Derevschikov, Anatoly A. ; Didenko, Lidia ; Draper, James E. ; Dunin, V. B. ; Dunlop, James C. ; Eckardt, Volker ; Efimov, Leonid G. ; Emelianov, V. ; Engelage, Jon M. ; Eppley, Geary Wareham ; Erazmus, Barbara Ewa ; Fachini, Patricia ; Ferguson, M. I. ; Finch, Evan ; Fisyak, Yuri V. ; Flierl, Dominik Bernhard ; Foley, K. J. ; Gagunashvili, N. ; Gans, J. ; Germain, Marie ; Geurts, Frank ; Ghazikhanian, Vahe ; Grabski, J. ; Grachov, Oleg A. ; Greiner, D. ; Grigoriev, Vladislav A. ; Gushin, E. ; Hallman, Timothy J. ; Hardtke, David H. ; Harris, John W. ; Heffner, Michael D. ; Heppelmann, Steven Francis ; Herston, T. ; Hippolyte, Boris ; Hirsch, Andrew S. ; Hjort, Eric ; Hoffmann, Gerald W. ; Horsley, M. ; Huang, Huan Zhong ; Humanic, Thomas J. ; Hümmler, Holm Gero ; Igo, George J. ; Ishihara, A. ; Ivanshin, Yu. I. ; Jacobs, Peter Martin ; Jacobs, William W. ; Janik, Michał ; Johnson, I. ; Jones, Peter Graham ; Judd, Eleanor G. ; Kaneta, Kaneta ; Kaplan, Morton ; Keane, Declan ; Khodinov, A. ; Kisiel, Adam Ryszard ; Klay, Jennifer Lynn ; Klein, Spencer Robert ; Klyachko, A. ; Konstantinov, A. S. ; Kotchenda, L. ; Kovalenko, A. D. ; Kramer, M. ; Kravtsov, Peter ; Krueger, Keith William ; Kuhn, Christian Claude ; Kulikov, Anatoly I. ; Kunde, Gerd J. ; Kunz, Christopher Lee ; Kutuev, R. Kh. ; Kuznetsov, A. A. ; Lamas-Valverde, Jose ; Lamont, Matthew A. C. ; Landgraf, Jeffery M. ; Lange, S. ; Lansdell, Curtis Patrick Leon ; Lasiuk, Brian ; Laue, Frank ; Lebedev, Alexei ; LeCompte, T. ; Leontiev, V. M. ; Leszczynski, P. ; LeVine, Micheal J. ; Li, Q. ; Li, Q. ; Lindenbaum, Sam J. ; Lisa, Michael A. ; Ljubicic, Tonko A. ; Llope, William Joseph ; LoCurto, G. ; Long, H. ; Longacre, Ronald S. ; Lopez-Noriega, M. ; Love, William A. ; Lynn, David ; Madansky, L. ; Majka, Richard Daniel ; Maliszewski, A. ; Margetis, Spyridon ; Martin, L. ; Marx, Jay N. ; Matis, Howard S. ; Matulenko, Yuri A. ; McShane, Tom S. ; Melnick, Yu. ; Meščanin, Aleksei P. ; Milosevich, Z. ; Minaev, Nikolai G. ; Mitchell, J. ; Moiseenko, V. A. ; Moltz, D. ; Moore, C. F. ; Morozov, V. ; de Moura, M. M. ; Munhoz, Marcelo Gameiro ; Mutchler, G. S. ; Nelson, John M. ; Nevski, P. ; Nikitin, Vladimir A. ; Nogach, Larisa V. ; Norman, B. ; Nurušev, Sandibek B. ; Nystrand, Joakim Ingemar ; Odyniec, Grazyna Janina ; Ogawa, Akio ; Ogilvie, C. A. ; Oldenburg, Markus D. ; Olson, Douglas L. ; Paic, Guy ; Pandey, S. U. ; Panebratsev, Yuri ; Panitkin, Sergei Yurievich ; Pavlinov, A. I. ; Pawlak, Tomasz Jan ; Perevoztchikov, V. ; Peryt, Wiktor Stanislaw ; Petrov, V. A. ; Pinganaud, W. ; Platner, E. ; Pluta, Jan Marian ; Porile, Norbert T. ; Porter, Jeffrey Brent ; Poskanzer, Arthur M. ; Potrebenikova, E. ; Prindle, Duncan J. ; Pruneau, Claude A. ; Radomski, S. ; Rai, Gulshan ; Ravel, Olivier ; Ray, Robert L. ; Razin, Sergej V. ; Reichhold, Dennis Michael ; Reid, Jeffrey G. ; Retiere, Fabrice ; Ridiger, Alexey ; Ritter, Hans Georg ; Roberts, Jabus B. ; Rogachevski, O. V. ; Roy, Christelle Sophie ; Russ, D. ; Rykov, Vladimir L. ; Sakrejda, Iwona ; Sandweiss, Jack H. ; Saulys, A. C. ; Savin, Igor A. ; Schambach, Joachim ; Scharenberg, Rolf Paul ; Schmitz, Norbert ; Schroeder, Lee S. ; Schüttauf, Andreas ; Seger, Janet Elizabeth ; Seliverstov, D. ; Seyboth, Peter ; Shestermanov, Konstantin E. ; Shimanskii, S. S. ; Shvetcov, V. S. ; Skoro, Goran P. ; Smirnov, Nikolai ; Snellings, Raimond ; Sowinski, James ; Spinka, Harold. M. ; Srivastava, Brijesh Kumar ; Stephenson, Edward J. ; Stock, Reinhard ; Stolpovsky, Alexander ; Strichanov, Michail Nikolaevič ; Stringfellow, Blair ; Ströbele, Herbert ; Struck, Christof ; Suaide, Alexandre Alarcon do Passo ; Sugarbaker, Evan R. ; Suire, Christophe Pierre ; Symons, Timothy James MacNeil ; Toledo, Alejandro Szanto de ; Szarwas, Piotr ; Takahashi, Jun ; Tang, Aihong ; Thomas, James H. ; Tikhomirov, V. ; Trainor, Thomas A. ; Trentalange, Stephen ; Tokarev, Mikhail V. ; Tonjes, Marguerite Belt ; Trofimov, V. ; Tsai, Oleg D. ; Turner, K. ; Ullrich, Thomas ; Underwood, David G. ; Van Buren, Gene ; VanderMolen, A. M. ; Vanyashin, A. ; Vasilevski, I. M. ; Vasiliev, Alexander Nikolaevich ; Vigdor, Steven E. ; Voloshin, Sergei ; Wang, F. ; Ward, H. ; Wells, R. ; Wenaus, T. ; Westfall, Gary D. ; Whitten, Charles A. ; Wieman, Howard ; Willson, Robert ; Wissink, Scott W. ; Witt, Richard ; Xu, N. ; Xu, Z. ; Yakutin, A. E. ; Yamamoto, E. ; Yang, J. ; Yepes, Pablo P. ; Yokosawa, A. ; Yurevich, Vladimir Yurevich ; Zanevski, Y. V. ; Zhang, J. ; Zhang, W. M. ; Zoulkarneev, R. ; Zubarev, A. N.
We report results on the ratio of midrapidity antiproton-to-proton yields in Au+Au collisions at sqrt[sNN] = 130 GeV per nucleon pair as measured by the STAR experiment at RHIC. Within the rapidity and transverse momentum range of | y|<0.5 and 0.4<pt<1.0 GeV/c, the ratio is essentially independent of either transverse momentum or rapidity, with an average of 0.65±0.01(stat)±0.07(syst) for minimum bias collisions. Within errors, no strong centrality dependence is observed. The results indicate that at this RHIC energy, although the p-p-bar pair production becomes important at midrapidity, a significant excess of baryons over antibaryons is still present.