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27 results on '"J. I. Jørdre"'

1. Quark–gluon plasma and color glass condensate at RHIC? The perspective from the BRAHMS experiment

Author

Bjørn Hallvard Samset, C. E. Jørgensen, J. Cibor, Calin Besliu, M. Mikelsen, F. Jundt, C. Chasman, Stephen Sanders, K. Hagel, I. S. Zgura, Anders Holm, D. R. Beavis, Catalin-Lucian Ristea, R. A. Scheetz, Oana Ristea, Borge Svane Nielsen, M. Germinario, Gunnar Løvhøiden, J. I. Jørdre, E. Enger, A. Makeev, Z. Majka, Ian Gardner Bearden, Trine Spedstad Tveter, P. Staszel, F. Videbæk, Y.K. Lee, R. Wada, A. K. Holme, Dieter Røhrich, Zhongbao Yin, B. Neumann, J. J. Gaardhøje, E. Jakobsen, Jongmin Lee, Michael Murray, B. Budick, Al. Jipa, D. Sandberg, S. Lindahl, R. R. Debbe, H. Ito, Peter Christiansen, I. Arsene, Christian Holm Christensen, E. J. Kim, Tomasz Kozik, R. Płaneta, Ole Hansen, R. Karabowicz, Fouad Rami, H. Bøggild, D. Ouerdane, J. B. Natowitz, T. M. Larsen, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and BRAHMS

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Nuclear Theory, High Energy Physics::Phenomenology, Hadron, FOS: Physical sciences, Plasma, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Color-glass condensate, Nuclear physics, Quark–gluon plasma, Energy density, Bibliography, High Energy Physics::Experiment, Heavy ion, Nuclear Experiment (nucl-ex), Nuclear Experiment, Jet quenching
Abstract

We review the main results obtained by the BRAHMS collaboration on the properties of hot and dense hadronic and partonic matter produced in ultrarelativistic heavy ion collisions at RHIC. A particular focus of this paper is to discuss to what extent the results collected so far by BRAHMS, and by the other three experiments at RHIC, can be taken as evidence for the formation of a state of deconfined partonic matter, the so called quark-gluon-plasma (QGP). We also discuss evidence for a possible precursor state to the QGP, i.e. the proposed Color Glass Condensate., 32 pages, 18 figures

Published
2005

2. RECENT RESULTS FROM THE BRAHMS EXPERIMENT AT RHIC

Author

Z. Yin, Z. Majka, B. Neuman, C. Ristea, Stephen Sanders, Borge Svane Nielsen, Gunnar Løvhøiden, J. I. Jørdre, Y. K. Lee, Christian Holm Christensen, H. Bøggild, P. Staszel, D. Ouerdane, I. Arsene, J. B. Natowitz, Calin Besliu, K. Hagel, Tomasz Kozik, H. Ito, Svein Lindal, Alexandru Jipa, D. Sandberg, B. Budick, M. Mikelsen, F. Jundt, Peter Christiansen, Ian Gardner Bearden, Dieter Røhrich, Trine Spedstad Tveter, Jongmin Lee, T. M. Larsen, R. R. Debbe, R. Lystad, R. Pł Aneta, I. S. Zgura, R. Karabowicz, Fouad Rami, Michael D. Murray, F. Videbæk, E. J. Kim, E. Enger, D. R. Beavis, A. Makeev, J. J. Gaardhøje, Oana Ristea, R. A. Sheetz, R. Wada, J. Cibor, C. Chasman, M. Germinario, Bjørn Hallvard Samset, C. E. Jørgensen, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Berndt Müller, Chung-I Tan, and BRAHMS

Subjects
Physics, Nuclear and High Energy Physics, High Energy Density Matter, Astronomy and Astrophysics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Atomic and Molecular Physics, and Optics, Charged particle, 25.75.-q, 25.75.Dw, Color-glass condensate, Nuclear physics, Reaction dynamics, Quark–gluon plasma, Particle, Rapidity, Nuclear Experiment, Relativistic Heavy Ion Collider
Abstract

We present the results obtained by the BRAHMS experiment at the Relativistic Heavy Ion Collider (RHIC) for three colliding systems, namely: Au + Au , d + Au and p + p at [Formula: see text]. The main focus here is to give an overview of the main results on the reaction dynamics and on the properties of hot and high energy density matter produced in utra-relativistic heavy ion collisions. Measurement of particle production, particle spectra over a large rapidity interval as well as high pt measurements related to nuclear modification in Au + Au and d + Au collision are discussed. The observed number of charged particles produced per unit of rapidity at the central rapidity region indicates that a high energy density (> 5 GeV/fm3) system is created at the initial stage of the Au + Au reaction. From the particle spectra we deduced significant radial expansion (β ≈ 0.75) which is consistent with the large initial energy density. For Au + Au at η = 0 we observe the suppression of the high p T particles as compared to the elementary collisions, whereas for the d + Au reaction the Cronin type enhancement is observed. We also discuss to what extent these results can be taken as evidence for the quark gluon plasma (QGP). Finally, we present the nuclear modification effects in d + Au reaction as a function of rapidity and consider whether the observed suppression at forward rapidities constitutes sufficient evidence for a possible precursor state to the QGP, i.e. the Color Glass Condensate (CGC).

Published
2005

3. Forward and midrapidity like-particle ratios from p+p collisions at s=200 GeV

Author

J. I. Jørdre, P. Staszel, Michael Murray, Ian Gardner Bearden, Stephen Sanders, H. Bøggild, D. Ouerdane, Dieter Røhrich, A. Wieloch, C. Chasman, K. Hagel, Gunnar Løvhøiden, M. Mikelsen, J. Cibor, F. Jundt, Y. K. Lee, D. Sandberg, M. Germinario, E. Jakobsen, Jongmin Lee, J. B. Natowitz, R. R. Debbe, Bjørn Hallvard Samset, K. Olchanski, D Rohrich, C. E. Jørgensen, A. K. Holme, Christian Holm Christensen, E. J. Kim, D. R. Beavis, Alexandru Jipa, F. Videbæk, E. Enger, Z. Majka, J. Norris, R. Płaneta, JI Jordre, Peter Christiansen, R. A. Scheetz, I. S. Zgura, H. Ito, Anders Holm, R. Karabowicz, Fouad Rami, J. J. Gaardhøje, B. Budick, T. Keutgen, A. Makeev, T. M. Larsen, Tomasz Kozik, Calin Besliu, R. Wada, Z. Yin, Trine Spedstad Tveter, C. Ristea, and Borge Svane Nielsen

Subjects
Baryon, Physics, Nuclear and High Energy Physics, Transverse momentum, Theoretical models, Rapidity, Baryon number, Atomic physics, Rest frame, Beam energy
Abstract

We present a measurement of π − / π + , K − / K + and p ¯ / p from p + p collisions at s = 200 GeV over the rapidity range 0 y 3.4 . For p T 2.0 GeV / c we see no significant transverse momentum dependence of the ratios. All three ratios are independent of rapidity for y ≲ 1.5 and then steadily decline from y ∼ 1.5 to y ∼ 3 . The π − / π + ratio is below unity for y > 2.0 . The p ¯ / p ratio is very similar for p + p and 20% central Au + Au collisions at all rapidities. In the fragmentation region the three ratios seem to be independent of beam energy when viewed from the rest frame of one of the protons. Theoretical models based on quark–diquark breaking mechanisms overestimate the p ¯ / p ratio up to y ≲ 3 . Including additional mechanisms for baryon number transport such as baryon junctions leads to a better description of the data.

Published
2005

4. Rapidity dependent strangeness measurements in BRAHMS experiment at RHIC

Author

J H Lee, (for the BRAHMIS Collaboration), I G Bearden, D Beavis, C Besliu, B Budick, H Bøggild, C Chasman, C H Christensen, P Christiansen, J Cibor, R Debbe, E Enger, J J Gaardhøje, M Germinario, K Hagel, O Hansen, A Holm, H Ito, E Jakobsen, A Jipa, F Jundt, J I Jørdre, C E Jørgensen, R Karabowicz, E J Kim, T Kozik, T M Larsen, Y K Lee, G Løvhøiden, Z Majka, A Makeev, M Mikelsen, M Murray, J Natowitz, B S Nielsen, J Norris, K Olchanski, J Olness, D Ouerdane, R P aneta, F Rami, C Ristea, D Röhrich, B H Samset, D Sandberg, S J Sanders, P Staszel, T S Tveter, F Videbæk, R Wada, A Wieloch, Z Yin, and I S Zgura

Subjects
Physics, Nuclear physics, Nuclear reaction, Nuclear and High Energy Physics, Particle physics, Pion, Meson, Hadron, Transverse mass, Rapidity, Strangeness, Nuclear Experiment, Charged particle
Abstract

Particle production of charged kaons in central Au+Au collisions at has been studied as a function of rapidity by the BRAHMS collaboration at RHIC. The kaon spectral shapes are described well by an exponential in transverse mass for the rapidity range of 0 ≤ yK ≤ 3.3 with smoothly decreasing inverse slopes as the rapidity increases. For the charged kaon to pion ratios, while there is no significant rapidity dependence for the K+/π+ ratio, the K−/π− ratio shows a significant decrease from y ≈ 1 towards higher rapidities. The systematics of K−/K+ and ratios in the measured rapidity range demonstrates a strongly correlated behaviour which can be described by thermal–statistical models.

Published
2003

5. The BRAHMS experiment at RHIC

Author

F. Jundt, L. Dutka, L Antvorskov, M Kajetanowicz, Borge Svane Nielsen, E. Jakobsen, Jongmin Lee, Zbigniew Sosin, M Adamczyk, J. Westergaard, T. Keutgen, A. Makeev, D. R. Beavis, K Ashktorab, Christian Holm Christensen, E.K. Olsen, B. Budick, P. Staszel, R. Planeta, R. A. Scheetz, F. Videbæk, Michael Murray, Z. Majka, Tomasz Kozik, K. Hagel, J. Hammond, Gunnar Løvhøiden, Dieter Røhrich, K. Grotowski, T. M. Larsen, Bjørn Hallvard Samset, Y. Blyakhman, J. Brzychczyk, H. Bøggild, E. Baker, Al. Jipa, D. Ouerdane, J. B. Natowitz, R. Wada, H. Ito, R. Debbe, A. K. Holme, C. E. Jørgensen, E. J. Kim, J Sørensen, E Kotula, Calin Besliu, N. Lindegaard, Peter Christiansen, I. S. Zgura, K. Olchanski, C. Pearson, O.B. Rasmussen, Anders Holm, J. J. Gaardhøje, J. Cibor, A. Wieloch, Trine Spedstad Tveter, K Pena, K. Asselta, Ole Hansen, Y. K. Lee, C. Chasman, J Engelhardt, D. Phillips, E McBreen, J. I. Jørdre, H Diaz, M Justice, Ian Gardner Bearden, J.W. Olness, Fouad Rami, J.C. Hansen, T.F. Thorsteinsen, and Stephen Sanders

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Spectrometer, Physics::Instrumentation and Detectors, Tracking (particle physics), Particle identification, Nuclear physics, Momentum, Quark–gluon plasma, High Energy Physics::Experiment, Rapidity, Nuclear Experiment, Instrumentation, Event (particle physics), Cherenkov radiation
Abstract

The BRAHMS experiment at RHIC was conceived to pursue the understanding of nuclear matter under extreme conditions by detailed measurements of charged hadrons over the widest possible range of rapidity and transverse momentum. The experiment consists of two spectrometers with complementary charged hadron detection capabilities as well as a series of global detectors for event characterization. A series of tracking detectors, time-of-flight arms and Cherenkov detectors enables momentum determination and particle identification over a wide range of rapidity and transverse momentum. Technical details and performance results are presented for the various detector subsystems. The performance of the entire system working together is shown to meet the goals of the experiment.

Published
2003

6. Strangeness production in $\sqrt{s_{NN}} = 200$ GeV Au+Au collisions at RHIC

Author

B. Budick, Alexandru Jipa, Gunnar Løvhøiden, Y. K. Lee, E. Enger, Tomasz Kozik, C. Chasman, Ian Gardner Bearden, Bjørn Hallvard Samset, Jongmin Lee, B. McBreen, Dieter Røhrich, Stephen Sanders, Peter Christiansen, Ole Hansen, C. E. Jørgensen, Christian Holm Christensen, Z. Yin, C. Ristea, K. Hagel, R. R. Debbe, Borge Svane Nielsen, I. Arsene, R. Płaneta, M. Germinario, Calin Besliu, R. A. Scheetz, J. I. Jørdre, J. Cibor, M. Mikelsen, F. Jundt, I. S. Zgura, Trine Spedstad Tveter, B. Neumann, Anders Holm, E. J. Kim, R. Karabowicz, Fouad Rami, D. Sandberg, Oana Ristea, P. Staszel, D. R. Beavis, R. Wada, A. Makeev, T. M. Larsen, J. Norris, H. Bøggild, D. Ouerdane, J. B. Natowitz, H. Ito, Svein Lindal, R. Lystad, Z. Majka, Michael D. Murray, F. Videbæk, J. J. Gaardhøje, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and BRAHMS

Subjects
Physics, Physics and Astronomy (miscellaneous), Nuclear Theory, Strangeness production, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Resonance (particle physics), Spectral line, Nuclear physics, Pion, 25.75.Dw Particle and resonance production, High Energy Physics::Experiment, Production (computer science), Rapidity, Nuclear Experiment, Engineering (miscellaneous)
Abstract

The BRAHMS collaboration has measured identified particle spectra from Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Rapidity densities are deduced from fits to the pion and kaon spectra. dN/dy is plotted as a function of rapidity and 4π yields and ratios are calculated. The signed K/π ratios are compared to values obtained at lower energies. We find that K–/π– increases monotonically from the AGS and SPS regimes, while K+/π+ is similar to what was found at the highest $\sqrt{s_{NN}}$ at SPS. PACS: 25.75.Dw Particle and resonance production

Published
2004

7. Results from the BRAHMS experiment at RHIC

Author

J. I. Jørdre, Bjørn Hallvard Samset, J. Norris, M. Mikkelsen, R. A. Sheetz, Y. Blyakhman, Stephen Sanders, K. Grotowski, Ole Hansen, A. K. Holme, D. Sandberg, K. Hagel, C. E. Jørgensen, T. M. Larsen, I. S. Zgura, K. Olchanski, F. Videbæk, P. Staszel, B. McBreen, J. J. Gaardhøje, R. Karabowicz, Fouad Rami, Trine Spedstad Tveter, Dieter Røhrich, R. Planeta, R. R. Debbe, Alexandru Jipa, Dieter Roehrich, J. B. Natowitz, Ian Gardner Bearden, T. Keutgen, Tomasz Kozik, C. Chasman, A. Makeev, Gunnar Løvhøiden, H. Ito, E. Enger, Michael D. Murray, Y. K. Lee, F. Jundt, B. Budick, M. Germinario, J. Cibor, Christian Holm Christensen, E. J. Kim, H. Bøggild, D. Ouerdane, J. Brzychczyk, Peter Christiansen, Borge Svane Nielsen, Calin Besliu, Z. Majka, R. Wada, Z. Yin, A. Wieloch, D. R. Beavis, E. Jakobsen, Jongmin Lee, and Zbigniew Sosin

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Meson, Nuclear Theory, Hadron, Elementary particle, Atomic and Molecular Physics, and Optics, Charged particle, Nuclear physics, Baryon, Pion, Pseudorapidity, High Energy Physics::Experiment, Rapidity, Nuclear Experiment
Abstract

Results from the BRAHMS collaboration for Au+Au collisions at √ S NN = 200 GeV are presented, focussing on the measurement of the net-proton rapidity distribution, the determination of the pseudorapidity distribution of charged particles and on the rapidity distributions of pions and kaons.

Published
2003

8. Centrality dependent particle production aty=0andy~1in Au+Au collisions atsNN=200 GeV

Author

Trine Spedstad Tveter, Stephen Sanders, B. Budick, K. Hagel, Bjørn Hallvard Samset, C. E. Jørgensen, Calin Besliu, C. Chasman, H. Ito, J. Cibor, Jongmin Lee, Ian Gardner Bearden, A. Makeev, D. R. Beavis, Gunnar Løvhøiden, Z. Majka, Y. K. Lee, P. Staszel, Tomasz Kozik, Borge Svane Nielsen, B. Neumann, Alexandru Jipa, R. R. Debbe, D. Sandberg, M. Germinario, Peter Christiansen, T. M. Larsen, R. Karabowicz, Fouad Rami, R. Wada, J. I. Jørdre, Christian Holm Christensen, E. J. Kim, F. Videbæk, Z. Yin, C. Ristea, R. A. Scheetz, I. Arsene, I. S. Zgura, Oana Ristea, R. Płaneta, M. Mikelsen, F. Jundt, J. J. Gaardhøje, E. Enger, Dieter Røhrich, H. Bøggild, D. Ouerdane, J. B. Natowitz, Michael D. Murray, Svein Lindal, and R. Lystad

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Meson, 010308 nuclear & particles physics, Nuclear Theory, Hadron, Elementary particle, 01 natural sciences, 7. Clean energy, Baryon, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Production (computer science), Nuclear Experiment, 010306 general physics, Nucleon, Centrality
Abstract

Particle production of identified charged hadrons, ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}},{K}^{\ifmmode\pm\else\textpm\fi{}},p$, and $\overline{p}$ in Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}=$ 200 GeV, has been studied as a function of transverse momentum and collision centrality at $y=0$ and $y~1$ by the BRAHMS experiment at Brookhaven National Laboratory's Relativistic Heavy-Ion Collider. Significant collective transverse flow at kinetic freeze-out has been observed in the collisions. The magnitude of the flow rises with the collision centrality. Proton and kaon yields relative to the pion production increase strongly as the transverse momentum increases and also increase with centrality. Particle yields per participant nucleon show a weak dependence on the centrality for all particle species. Hadron production remains relatively constant within one unit around midrapidity in Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}=$ 200 GeV.

Published
2005

9. Charged Meson Rapidity Distributions in CentralAu+AuCollisions atsNN=200 GeV

Author

F. Videbæk, J. J. Gaardhøje, Bjørn Hallvard Samset, P. Staszel, R. Karabowicz, Fouad Rami, I. S. Zgura, C. E. Jørgensen, Michael Murray, Anders Holm, J. Norris, Stephen Sanders, Ian Gardner Bearden, D. Sandberg, Dieter Røhrich, T. M. Larsen, M. Germinario, M. Mikelsen, F. Jundt, K. Hagel, R. A. Sheetz, C. Chasman, E. Enger, H. Bøggild, D. Ouerdane, J. B. Natowitz, Christian Holm Christensen, E. J. Kim, H. Ito, B. Budick, J. Cibor, J. I. Jørdre, R. Płaneta, A. Makeev, D. R. Beavis, A. K. Holme, R. R. Debbe, Alexandru Jipa, K. Olchanski, Gunnar Løvhøiden, R. Wada, Ole Hansen, Y. K. Lee, Tomasz Kozik, Peter Christiansen, Jongmin Lee, Trine Spedstad Tveter, Z. Yin, C. Ristea, Borge Svane Nielsen, Calin Besliu, and Z. Majka

Subjects
Nuclear physics, Physics, Range (particle radiation), Particle physics, Pion, Meson, General Physics and Astronomy, Rapidity, Central region, Longitudinal direction
Abstract

We have measured rapidity densities dN/dy of pi+/- and K+/- over a broad rapidity range (-0.1 < y < 3.5) for central Au + Au collisions at square root(sNN) = 200 GeV. These data have significant implications for the chemistry and dynamics of the dense system that is initially created in the collisions. The full phase-space yields are 1660 +/- 15 +/- 133 (pi+), 1683 +/- 16 +/- 135 (pi-), 286 +/- 5 +/- 23 (K+), and 242 +/- 4 +/- 19 (K-). The systematics of the strange to nonstrange meson ratios are found to track the variation of the baryochemical potential with rapidity and energy. Landau-Carruthers hydrodynamics is found to describe the bulk transport of the pions in the longitudinal direction.

Published
2005

10. Centrality Dependence of Charged-Particle Pseudorapidity Distributions fromd+AuCollisions atsNN=200 GeV

Author

M. Mikelsen, F. Jundt, J. I. Jørdre, Stephen Sanders, Calin Besliu, R. R. Debbe, Christian Holm Christensen, Ian Gardner Bearden, K. Hagel, E. J. Kim, Y.K. Lee, Jongmin Lee, B. Budick, Trine Spedstad Tveter, R. Płaneta, Alexandru Jipa, R. Wada, C. Chasman, D. Sandberg, I. S. Zgura, Tomasz Kozik, Bjørn Hallvard Samset, M. Germinario, I. Arsene, Z. Yin, C. Ristea, Dieter Røhrich, C. E. Jørgensen, Z. Majka, Borge Svane Nielsen, B. Neumann, E. Enger, J. Cibor, A. Makeev, R. Karabowicz, Fouad Rami, Oana Ristea, Gunnar Løvhøiden, R. A. Sheetz, D. R. Beavis, P. Staszel, Peter Christiansen, T. M. Larsen, F. Videbæk, J. J. Gaardhøje, Michael D. Murray, H. Bøggild, D. Ouerdane, J. B. Natowitz, H. Ito, Svein Lindal, and R. Lystad

Subjects
Quantum chromodynamics, Nuclear reaction, Physics, Particle physics, General Physics and Astronomy, Perturbative QCD, Semiclassical physics, Charged particle, Nuclear physics, Pseudorapidity, High Energy Physics::Experiment, Quantum field theory, Nuclear Experiment, Centrality
Abstract

Charged-particle pseudorapidity densities are presented for the $d+\mathrm{A}\mathrm{u}$ reaction at $\sqrt{{s}_{NN}}=200\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$ with $\ensuremath{-}4.2\ensuremath{\le}\ensuremath{\eta}\ensuremath{\le}4.2$. The results, from the BRAHMS experiment at BNL Relativistic Heavy-Ion Collider, are shown for minimum-bias events and 0%--30%, 30%--60%, and 60%--80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semiclassical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap $d+\mathrm{A}\mathrm{u}$ results at $\sqrt{{s}_{NN}}=19.4\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$.

Published
2005

11. Evolution of the Nuclear Modification Factors with Rapidity and Centrality ind+AuCollisions atNNS=200 GeV

Author

A. Makeev, Stephen Sanders, F. Videbæk, Jongmin Lee, H. Bøggild, D. Ouerdane, K. Hagel, P. Staszel, J. B. Natowitz, Borge Svane Nielsen, M. Mikelsen, Svein Lindal, R. Karabowicz, R. Wada, F. Jundt, Calin Besliu, R. Lystad, I. Arsene, Trine Spedstad Tveter, J. J. Gaardhøje, H. Ito, Y. K. Lee, R. A. Scheetz, B. Neumann, Dieter Røhrich, Alexandru Jipa, Z. Majka, Tomasz Kozik, M. Germinario, Oana Ristea, Fouad Rami, I. S. Zgura, B. Budick, D. Sandberg, Gunnar Løvhøiden, D. R. Beavis, Christian Holm Christensen, Ian Gardner Bearden, E. J. Kim, T. M. Larsen, E. Enger, R. R. Debbe, Peter Christiansen, Michael D. Murray, R. Płaneta, J. I. Jørdre, Z. Yin, C. Ristea, C. Chasman, J. Cibor, Bjørn Hallvard Samset, and C. E. Jørgensen

Subjects
Physics, Particle physics, Computer Science::Information Retrieval, Nuclear Theory, Hadron, General Physics and Astronomy, Computer Science::Computation and Language (Computational Linguistics and Natural Language and Speech Processing), Color-glass condensate, Gluon, Nuclear physics, Deuterium, Pseudorapidity, Saturation (graph theory), High Energy Physics::Experiment, Rapidity, Nuclear Experiment, Centrality
Abstract

We report on a study of the transverse momentum dependence of nuclear modification factors ${R}_{d\mathrm{A}\mathrm{u}}$ for charged hadrons produced in $\mathrm{\text{deuteron}}\text{ }\text{ }+\text{ }\text{ }\mathrm{\text{gold}}$ collisions at $\sqrt{{s}_{NN}}=200\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$, as a function of collision centrality and of the pseudorapidity ($\ensuremath{\eta}=0$, 1, 2.2, 3.2) of the produced hadrons. We find a significant and systematic decrease of ${R}_{d\mathrm{A}\mathrm{u}}$ with increasing rapidity. The midrapidity enhancement and the forward rapidity suppression are more pronounced in central collisions relative to peripheral collisions. These results are relevant to the study of the possible onset of gluon saturation at energies reached at BNL RHIC.

Published
2004

12. Nuclear Stopping inAu+AuCollisions atsNN=200 GeV

Author

I. G. Bearden, D. Beavis, C. Besliu, B. Budick, H. Bøggild, C. Chasman, C. H. Christensen, P. Christiansen, J. Cibor, R. Debbe, E. Enger, J. J. Gaardhøje, M. Germinario, K. Hagel, O. Hansen, A. Holm, A. K. Holme, H. Ito, A. Jipa, F. Jundt, J. I. Jørdre, C. E. Jørgensen, R. Karabowicz, E. J. Kim, T. Kozik, T. M. Larsen, J. H. Lee, Y. K. Lee, G. Løvhøiden, Z. Majka, A. Makeev, M. Mikelsen, M. Murray, J. Natowitz, B. S. Nielsen, J. Norris, K. Olchanski, D. Ouerdane, R. Płaneta, F. Rami, C. Ristea, D. Röhrich, B. H. Samset, D. Sandberg, S. J. Sanders, R. A. Scheetz, P. Staszel, T. S. Tveter, F. Videbæk, R. Wada, Z. Yin, and I. S. Zgura

Subjects
Nuclear physics, Physics, Range (particle radiation), Proton, Antiproton, Yield (chemistry), Transverse momentum, General Physics and Astronomy, Rapidity, Atomic physics, Nuclear Experiment, Nucleon, Spectral line
Abstract

Transverse momentum spectra and rapidity densities, dN/dy, of protons, antiprotons, and net protons (p-p) from central (0%-5%) Au+Au collisions at square root of S(NN)=200 GeV were measured with the BRAHMS experiment within the rapidity range 0

Published
2004

13. Charged meson rapidity distributions in central Au+Au collisions at square root(sNN) = 200 GeV

Author

I G, Bearden, D, Beavis, C, Besliu, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, M, Germinario, K, Hagel, O, Hansen, A, Holm, A K, Holme, H, Ito, A, Jipa, F, Jundt, J I, Jørdre, C E, Jørgensen, R, Karabowicz, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, G, Løvhøiden, Z, Majka, A, Makeev, M, Mikelsen, M, Murray, J, Natowitz, B S, Nielsen, J, Norris, K, Olchanski, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Sheetz, P, Staszel, T S, Tveter, F, Videaek, R, Wada, Z, Yin, and I S, Zgura

Abstract

We have measured rapidity densities dN/dy of pi+/- and K+/- over a broad rapidity range (-0.1y3.5) for central Au + Au collisions at square root(sNN) = 200 GeV. These data have significant implications for the chemistry and dynamics of the dense system that is initially created in the collisions. The full phase-space yields are 1660 +/- 15 +/- 133 (pi+), 1683 +/- 16 +/- 135 (pi-), 286 +/- 5 +/- 23 (K+), and 242 +/- 4 +/- 19 (K-). The systematics of the strange to nonstrange meson ratios are found to track the variation of the baryochemical potential with rapidity and energy. Landau-Carruthers hydrodynamics is found to describe the bulk transport of the pions in the longitudinal direction.

Published
2004

14. Evolution of the nuclear modification factors with rapidity and centrality in d + Au collisions at (sqrt)[N(S)N]=200 GeV

Author

I, Arsene, I G, Bearden, D, Beavis, C, Besliu, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, M, Germinario, K, Hagel, H, Ito, A, Jipa, F, Jundt, J I, Jørdre, C E, Jørgensen, R, Karabowicz, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, S, Lindal, R, Lystad, G, Løvhøiden, Z, Majka, A, Makeev, M, Mikelsen, M, Murray, J, Natowitz, B, Neumann, B S, Nielsen, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, O, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Scheetz, P, Staszel, T S, Tveter, F, Videbaek, R, Wada, Z, Yin, and I S, Zgura

Abstract

We report on a study of the transverse momentum dependence of nuclear modification factors R(dAu) for charged hadrons produced in deuteron + gold collisions at sqrt[s(NN)]=200 GeV, as a function of collision centrality and of the pseudorapidity (eta=0, 1, 2.2, 3.2) of the produced hadrons. We find a significant and systematic decrease of R(dAu) with increasing rapidity. The midrapidity enhancement and the forward rapidity suppression are more pronounced in central collisions relative to peripheral collisions. These results are relevant to the study of the possible onset of gluon saturation at energies reached at BNL RHIC.

Published
2004

15. The New Physics at RHIC. From Transparency to High p$_t$ Suppression

Author

Ian Gardner Bearden, B. McBreen, Tomasz Kozik, Stephen Sanders, M. Germinario, Trine Spedstad Tveter, Ole Hansen, M. Mikelsen, Bjørn Hallvard Samset, I. S. Zgura, Calin Besliu, Y.K. Lee, F. Jundt, K. Hagel, R. A. Scheetz, P. Staszel, Anders Holm, C. E. Jørgensen, B. Budick, J. J. Gaardhøje, J. I. Jørdre, Christian Holm Christensen, Z. Majka, H. Bøggild, D. Ouerdane, J. B. Natowitz, H. Ito, Oana Ristea, Michael D. Murray, Z. Yin, R. Płaneta, Svein Lindal, T. M. Larsen, C. Ristea, R. Lystad, Borge Svane Nielsen, D. Sandberg, R. R. Debbe, C. Chasman, J. Norris, Alexandru Jipa, D. R. Beavis, R. Wada, J. Cibor, Jongmin Lee, E. Enger, R. Karabowicz, A. Makeev, D. Ro¨hrich, E. J. Kim, Fouad Rami, Gunnar Løvhøiden, Peter Christiansen, I. Arsene, and B. Neumann

Subjects
Thermal equilibrium, Nuclear reaction, Physics, Nuclear and High Energy Physics, Hadron, FOS: Physical sciences, Parton, Charged particle, Nuclear physics, Color model, Strange matter, Quark–gluon plasma, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Atomic physics, Nuclear Experiment
Abstract

Heavy ion collisions at RHIC energies (Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV) exhibit significant new features as compared to earlier experiments at lower energies. The reaction is characterized by a high degree of transparency of the collisions partners leading to the formation of a baryon-poor central region. In this zone, particle production occurs mainly from the stretching of the color field. The initial energy density is well above the one considered necessary for the formation of the Quark Gluon Plasma, QGP. The production of charged particles of various masses is consistent with chemical and thermal equilibrium. Recently, a suppression of the high transverse momentum component of hadron spectra has been observed in central Au+Au collisions. This can be explained by the energy loss experienced by leading partons in a medium with a high density of unscreened color charges. In contrast, such high $p_t$ jets are not suppressed in d+Au collisions suggesting that the high $p_t$ suppression is not due to initial state effects in the ultrarelativistic colliding nuclei., 15 pages, 11 figures. to appear in Nucl. Physics A. Invited talk at 'Nucleus-Nucleus Collisions 2003' conference, Moscow

Published
2004

16. Centrality dependence of charged-particle pseudorapidity distributions from d + Au collisions at sqrt[sNN] = 200 GeV

Author

I, Arsene, I G, Bearden, D, Beavis, C, Besliu, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, M, Germinario, K, Hagel, H, Ito, A, Jipa, J I, Jørdre, F, Jundt, C E, Jørgensen, R, Karabowicz, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, S, Lindal, R, Lystad, G, Løvhøiden, Z, Majka, A, Makeev, M, Mikelsen, M, Murray, J, Natowitz, B, Neumann, B S, Nielsen, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, O, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Sheetz, P, Staszel, T S, Tveter, F, Videbaek, R, Wada, Z, Yin, and I S, Zgura

Abstract

Charged-particle pseudorapidity densities are presented for the d + Au reaction at sqrt[s(NN)] = 200 GeV with -4.2or = etaor = 4.2. The results, from the BRAHMS experiment at BNL Relativistic Heavy-Ion Collider, are shown for minimum-bias events and 0%-30%, 30%-60%, and 60%-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semiclassical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt[s(NN)] = 19.4 GeV.

Published
2004

17. Nuclear stopping in Au+Au collisions at square root of S(NN)=200 GeV

Author

I G, Bearden, D, Beavis, C, Besliu, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, M, Germinario, K, Hagel, O, Hansen, A, Holm, A K, Holme, H, Ito, A, Jipa, F, Jundt, J I, Jørdre, C E, Jørgensen, R, Karabowicz, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, G, Løvhøiden, Z, Majka, A, Makeev, M, Mikelsen, M, Murray, J, Natowitz, B S, Nielsen, J, Norris, K, Olchanski, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Scheetz, P, Staszel, T S, Tveter, F, Videbaek, R, Wada, Z, Yin, and I S, Zgura

Abstract

Transverse momentum spectra and rapidity densities, dN/dy, of protons, antiprotons, and net protons (p-p) from central (0%-5%) Au+Au collisions at square root of S(NN)=200 GeV were measured with the BRAHMS experiment within the rapidity range 0/=y/=3. The proton and antiproton dN/dy decrease from midrapidity to y=3. The net-proton yield is roughly constant for y1 at dN/dy approximately 7, and increases to dN/dy approximately 12 at y approximately 3. The data show that collisions at this energy exhibit a high degree of transparency and that the linear scaling of rapidity loss with rapidity observed at lower energies is broken. The energy loss per participant nucleon is estimated to be 73+/-6 GeV.

Published
2003

18. Transverse-Momentum Spectra inAu+Auandd+AuCollisions atsNN=200 GeVand the Pseudorapidity Dependence of High-pTSuppression

Author

F. Videbæk, G. Lystad, J. J. Gaardhøje, E. Enger, I. S. Zgura, Jongmin Lee, Anders Holm, M. Mikelsen, F. Jundt, Michael D. Murray, Z. Majka, B. McBreen, A. Makeev, T. M. Larsen, Dieter Røhrich, Ian Gardner Bearden, J. Cibor, J. I. Jørdre, Borge Svane Nielsen, B. Budick, B. Neumann, Trine Spedstad Tveter, Stephen Sanders, D. R. Beavis, Y. K. Lee, K. Hagel, C. Chasman, Bjørn Hallvard Samset, C. E. Jørgensen, Z. Yin, C. Ristea, Calin Besliu, R. Karabowicz, P. Staszel, H. Bøggild, R. R. Debbe, D. Ouerdane, I. Arsene, E. J. Kim, J. B. Natowitz, Alexandru Jipa, H. Ito, Svein Lindal, M. Germinario, D. Sandberg, J. Norris, R. A. Scheetz, Oana Ristea, R. Wada, Ole Hansen, Christian Holm Christensen, Gunnar Løvhøiden, R. Płaneta, Peter Christiansen, Fouad Rami, and Tomasz Kozik

Subjects
Physics, Energy loss, Particle physics, Pseudorapidity, Transverse momentum, Hadron, General Physics and Astronomy, Modification factor, Atomic physics, Nuclear Experiment, Spectral line, Energy (signal processing)
Abstract

We present spectra of charged hadrons from $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ and $d+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{{s}_{NN}}=200\text{ }\mathrm{G}\mathrm{e}\mathrm{V}$ measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from $p+\overline{p}$ collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at $\ensuremath{\eta}=0$ and $\ensuremath{\eta}=2.2$ evidence a strong suppression in the high ${p}_{T}$ region ($g2\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/c$). In contrast, the $d+\mathrm{A}\mathrm{u}$ nuclear modification factor (at $\ensuremath{\eta}=0$) exhibits an enhancement of the high ${p}_{T}$ yields. These measurements indicate a high energy loss of the high ${p}_{T}$ particles in the medium created in the central $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions. The lack of suppression in $d+\mathrm{A}\mathrm{u}$ collisions makes it unlikely that initial state effects can explain the suppression in the central $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions.

Published
2003

19. High $p_T$ results for Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

Author

D. Sandberg, Jongmin Lee, M. Germinario, Z. Majka, Calin Besliu, Michael D. Murray, Ian Gardner Bearden, Borge Svane Nielsen, Christian Holm Christensen, F. Videbæk, R. A. Scheetz, Oana Ristea, Stephen Sanders, K. Hagel, Alexandru Jipa, Peter Christiansen, R. Płaneta, Trine Spedstad Tveter, Z. Yin, C. Ristea, R. Karabowicz, Fouad Rami, J. J. Gaardhøje, J. I. Jørdre, I. S. Zgura, J. Norris, I. Arsene, R. Wada, Anders Holm, E. J. Kim, Gunnar Løvhøiden, Y. K. Lee, P. Staszel, B. Neumann, A. Makeev, M. Mikelsen, F. Jundt, Tomasz Kozik, J. Cibor, Bjørn Hallvard Samset, Ole Hansen, C. E. Jørgensen, B. Budick, C. Chasman, R. R. Debbe, B. McBreen, Dieter Røhrich, E. Enger, H. Bøggild, D. Ouerdane, J. B. Natowitz, H. Ito, Svein Lindal, R. Lystad, T. M. Larsen, D. R. Beavis, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and BRAHMS

Subjects
Physics, Particle physics, Physics and Astronomy (miscellaneous), Hadron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Resonance (particle physics), Spectral line, Pion, Transverse momentum, Particle, 25.75.Dw Particle and resonance production, Rapidity, Nuclear Experiment, Engineering (miscellaneous)
Abstract

We present transverse momentum spectra of unidentified charged hadrons at two pseudo-rapidities (η = 0, 2.2) as well as the first results on identified negatively charged pions at rapidity 2.2 from Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. The high p T yields of charged hadrons in the most central collisions show a strong suppression when compared to expected binary-scaled yields from nucleon-nucleon collisions or semi-peripheral collisions. The π– spectra at forward rapidity (y = 2.2) also indicate a clear suppression of high p T π– yields in central collisions. PACS: 25.75.Dw Particle and resonance production

Published
2003

20. Transverse-momentum spectra in Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV and the pseudorapidity dependence of high-p(T) suppression

Author

I, Arsene, I G, Bearden, D, Beavis, C, Besliu, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, M, Germinario, K, Hagel, O, Hansen, A, Holm, H, Ito, A, Jipa, F, Jundt, J I, Jørdre, C E, Jørgensen, R, Karabowicz, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, S, Lindal, G, Lystad, G, Løvhøiden, Z, Majka, A, Makeev, B, McBreen, M, Mikelsen, M, Murray, J, Natowitz, B, Neumann, B S, Nielsen, J, Norris, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, O, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Scheetz, P, Staszel, T S, Tveter, F, Videbaek, R, Wada, Z, Yin, and I S, Zgura

Abstract

We present spectra of charged hadrons from Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+(-)p collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at eta=0 and eta=2.2 evidence a strong suppression in the high p(T) region (2 GeV/c). In contrast, the d+Au nuclear modification factor (at eta=0) exhibits an enhancement of the high p(T) yields. These measurements indicate a high energy loss of the high p(T) particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.

Published
2003

21. Rapidity Dependence of Charged Antihadron to Hadron Ratios inAu+AuCollisions atsNN=200 GeV

Author

R. A. Scheetz, D. Sandberg, Calin Besliu, Stephen Sanders, J. I. Jørdre, F. Videbæk, Z. Majka, Tomasz Kozik, J.W. Olness, K. Olchanski, Christian Holm Christensen, T. M. Larsen, T. Keutgen, K. Hagel, A. Wieloch, I. S. Zgura, A. Makeev, H. Bøggild, D. Ouerdane, E. Jakobsen, Jongmin Lee, Ole Hansen, J. B. Natowitz, H. Ito, R. Płaneta, Peter Christiansen, E. Enger, J. Norris, R. Wada, J. J. Gaardhøje, Anders Holm, Ian Gardner Bearden, R. R. Debbe, Trine Spedstad Tveter, Fouad Rami, Alexandru Jipa, Y. K. Lee, Y. Blyakhman, D. R. Beavis, M. Mikelsen, F. Jundt, A. K. Holme, Z. Yin, C. Ristea, Gunnar Løvhøiden, B. Budick, Borge Svane Nielsen, E. J. Kim, M. Germinario, Michael D. Murray, C. Chasman, J. Cibor, Bjørn Hallvard Samset, C. E. Jørgensen, R. Karabowicz, P. Staszel, B. McBreen, and Dieter Røhrich

Subjects
Nuclear reaction, Physics, Particle physics, Meson, Nuclear Theory, Hadron, General Physics and Astronomy, Nuclear physics, Baryon, Pion, Antimatter, Rapidity, Nuclear Experiment, Nucleon
Abstract

We present ratios of the numbers of charged antihadrons to hadrons (pions, kaons, and protons) in Au+Au collisions at sqrt[s(NN)]=200 GeV as a function of rapidity in the range y=0-3. While the ratios at midrapidity are approaching unity, the K(-)/K(+) and p;/p ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from mu(B) approximately 130 MeV at y=3 to mu(B) approximately 25 MeV at y=0.

Published
2003

22. Rapidity dependence of charged antihadron to hadron ratios in Au+Au collisions at $\sqrt{S_{NN}}$=200GeV

Author

I G, Bearden, D, Beavis, C, Besliu, Y, Blyakhman, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, M, Germinario, K, Hagel, O, Hansen, A, Holm, A K, Holme, H, Ito, E, Jakobsen, A, Jipa, F, Jundt, J I, Jørdre, C E, Jørgensen, R, Karabowicz, T, Keutgen, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, G, Løvhøiden, Z, Majka, A, Makeev, B, McBreen, M, Mikelsen, M, Murray, J, Natowitz, B S, Nielsen, J, Norris, K, Olchanski, J, Olness, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Scheetz, P, Staszel, T S, Tveter, F, Videbaek, R, Wada, A, Wieloch, Z, Yin, I S, Zgura, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and BRAHMS

Subjects
[PHYS.HPHE] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph]
Abstract

We present ratios of the numbers of charged antihadrons to hadrons (pions, kaons, and protons) in Au+Au collisions at sqrt[s(NN)]=200 GeV as a function of rapidity in the range y=0-3. While the ratios at midrapidity are approaching unity, the K(-)/K(+) and p;/p ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from mu(B) approximately 130 MeV at y=3 to mu(B) approximately 25 MeV at y=0.

Published
2003

23. Pseudorapidity Distributions of Charged Particles fromAu+AuCollisions at the Maximum RHIC Energy,sNN=200GeV

Author

E. Enger, J. H. Lee, A. Jipa, R. Wada, Ian Gardner Bearden, Anders Holm, B. McBreen, Borge Svane Nielsen, Michael Murray, Christian Holm Christensen, C. Chasman, Trine Spedstad Tveter, D. Beavis, R. Debbe, D. Sandberg, Y. Blyakhman, Y. K. Lee, R. Karabowicz, H. Ito, Ole Hansen, C. E. Jørgensen, J. Cibor, B. H. Samset, R. Płaneta, J. Norris, M. Mikelsen, T. Keutgen, P. Staszel, F. Videbaek, J. Natowitz, Peter Christiansen, A. Wieloch, R. A. Sheetz, K. Hagel, T. F. Thorsteinsen, J. I. Jørdre, E. Jakobsen, T. Kozik, K. Olchanski, T. M. Larsen, Catalin-Lucian Ristea, H. Bøggild, D. Ouerdane, J. Olness, Z. Majka, S. J. Sanders, A. K. Holme, B. Budick, C. Besliu, A. Makeev, F. Jundt, F. Rami, G. Løvhøiden, D. Röhrich, J. J. Gaardhøje, E. J. Kim, and I. S. Zgura

Subjects
Physics, Nuclear reaction, Particle physics, Pseudorapidity, Physics::Medical Physics, General Physics and Astronomy, Production (computer science), Atomic physics, Nuclear Experiment, Nucleon, Centrality, Energy (signal processing), Charged particle
Abstract

We present charged-particle multiplicities as a function of pseudorapidity and collision centrality for the ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ reaction at $\sqrt{{s}_{\mathrm{NN}}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}200\mathrm{GeV}$. For the $5%$ most central events we obtain ${\mathrm{dN}}_{\mathrm{ch}}/d\ensuremath{\eta}{|}_{\ensuremath{\eta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}625\ifmmode\pm\else\textpm\fi{}55$ and ${N}_{\mathrm{ch}}{|}_{\ensuremath{-}4.7\ensuremath{\le}\ensuremath{\eta}\ensuremath{\le}4.7}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4630\ifmmode\pm\else\textpm\fi{}370$, i.e., $14%$ and $21%$ increases, respectively, relative to $\sqrt{{s}_{\mathrm{NN}}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}130\mathrm{GeV}$ collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around midrapidity. These results constrain current models of particle production at the highest RHIC energy.

Published
2002

24. Pseudorapidity distributions of charged particles from Au + Au collisions at the maximum RHIC energy, square root[s(NN)] = 200 GeV

Author

I G, Bearden, D, Beavis, C, Besliu, Y, Blyakhman, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, E, Enger, J J, Gaardhøje, K, Hagel, O, Hansen, A, Holm, A K, Holme, H, Ito, E, Jakobsen, A, Jipa, J I, Jørdre, F, Jundt, C E, Jørgensen, R, Karabowicz, T, Keutgen, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, G, Løvhøiden, Z, Majka, A, Makeev, B, McBreen, M, Mikelsen, M, Murray, J, Natowitz, B S, Nielsen, J, Norris, K, Olchanski, J, Olness, D, Ouerdane, R, Płaneta, F, Rami, C, Ristea, D, Röhrich, B H, Samset, D, Sandberg, S J, Sanders, R A, Sheetz, P, Staszel, T F, Thorsteinsen, T S, Tveter, F, Videbaek, R, Wada, A, Wieloch, and I S, Zgura

Abstract

We present charged-particle multiplicities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at square root[s(NN)] = 200 GeV. For the 5% most central events we obtain dN(ch)/deta/(eta = 0) = 625+/-55 and N(ch)/(-4.7or =etaor =4.7) = 4630 +/- 370, i.e., 14% and 21% increases, respectively, relative to square root[s(NN)] = 130 GeV collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around midrapidity. These results constrain current models of particle production at the highest RHIC energy.

Published
2001

25. Rapidity Dependence of Antiproton-to-Proton Ratios inAu+AuCollisions atsNN=130GeV

Author

T. Keutgen, E. Jakobsen, Jongmin Lee, D. Ouerdane, Fouad Rami, P. Staszel, Zbigniew Sosin, A. Makeev, C. Chasman, R. Wada, H. Ito, Michael Murray, Alexandru Jipa, T.F. Thorsteinsen, J. Cibor, J. B. Natowitz, F. Jundt, Ian Gardner Bearden, J.W. Olness, Y. Blyakhman, Peter Christiansen, Bjørn Hallvard Samset, E. J. Kim, B. Budick, A. K. Holme, J. Brzychczyk, Christian Holm Christensen, K. Olchanski, Borge Svane Nielsen, C. E. Jørgensen, I. S. Zgura, R. A. Sheetz, Z. Majka, Dieter Røhrich, Calin Besliu, Anders Holm, H. Bøggild, Trine Spedstad Tveter, J. I. Jørdre, R. Płaneta, Gunnar Løvhøiden, Ole Hansen, Y. K. Lee, Tomasz Kozik, R. R. Debbe, Stephen Sanders, K. Hagel, B. McBreen, K. Grotowski, T. M. Larsen, D. R. Beavis, A. Wieloch, F. Videbæk, and J. J. Gaardhøje

Subjects
Physics, Range (particle radiation), Proton, Degree (graph theory), General Physics and Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Nuclear physics, Antiproton, Transverse momentum, High Energy Physics::Experiment, Rapidity, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Nuclear Experiment, Centrality, Bar (unit)
Abstract

Measurements, with the BRAHMS detector, of the antiproton-to-proton ratio at midrapidities and forward rapidities, are presented for Au+Au reactions at s{sub NN}=130 GeV , and for three different collision centralities. For collisions in the 0%--40% centrality range, we find N({bar p})/N(p)=0.64{+-} 0.04{sub (stat)}{+-}0.06{sub ( syst)} at y{approx}0 , 0.66{+-}0.03{+-}0.06 at y{approx}0.7 , and 0.41{+-}0.04{+-}0.06 at y{approx}2 . The ratios are found to be nearly independent of collision centrality and transverse momentum. The antiproton and proton rapidity densities vary differently with rapidity, and indicate a significant degree of collision transparency, although a net-baryon free midrapidity plateau (Bjorken limit) is not yet reached.

Published
2001

26. Rapidity dependence of antiproton-to-proton ratios in Au+Au collisions at square root of (sNN) = 130 GeV

Author

I G, Bearden, D, Beavis, C, Besliu, Y, Blyakhman, J, Brzychczyk, B, Budick, H, Bøggild, C, Chasman, C H, Christensen, P, Christiansen, J, Cibor, R, Debbe, J J, Gaardhøje, K, Grotowski, K, Hagel, O, Hansen, A, Holm, A K, Holme, H, Ito, E, Jakobsen, A, Jipa, J I, Jørdre, F, Jundt, C E, Jørgensen, T, Keutgen, E J, Kim, T, Kozik, T M, Larsen, J H, Lee, Y K, Lee, G L, Løvhøiden, Z, Majka, A, Makeev, B, McBreen, M, Murray, J, Natowitz, B S, Nielsen, K, Olchanski, J, Olness, D, Ouerdane, R, Planeta, F, Rami, D, Röhrich, B H, Samset, S J, Sanders, R A, Sheetz, Z, Sosin, P, Staszel, T F, Thorsteinsen, T S, Tveter, F, Videbaek, R, Wada, A, Wieloch, and I S, Zgura

Abstract

Measurements, with the BRAHMS detector, of the antiproton-to-proton ratio at midrapidities and forward rapidities, are presented for Au+Au reactions at square root of [s(NN)] = 130 GeV, and for three different collision centralities. For collisions in the 0%-40% centrality range, we find N(pmacr;)/N(p) = 0.64+/-0.04((stat))+/-0.06((syst)) at y approximately 0, 0.66+/-0.03+/-0.06 at y approximately 0.7, and 0.41+/-0.04+/-0.06 at y approximately 2. The ratios are found to be nearly independent of collision centrality and transverse momentum. The antiproton and proton rapidity densities vary differently with rapidity, and indicate a significant degree of collision transparency, although a net-baryon free midrapidity plateau (Bjorken limit) is not yet reached.

Published
2001

27. Charged particle multiplicities at BRAHMS

Author

Borge Svane Nielsen, Stephen Sanders, Trine Spedstad Tveter, Y. K. Lee, Michael D. Murray, K. Grotowski, R. Wada, Ian Gardner Bearden, J.W. Olness, T. M. Larsen, J. Cibor, K. Hagel, Peter Christiansen, F. Videbæk, Z. Majka, D. R. Beavis, R. R. Debbe, E. J. Kim, I. S. Zgura, Anders Holm, E. Jakobsen, Jongmin Lee, Zbigniew Sosin, J. J. Gaardhøje, Calin Besliu, J. I. Jørdre, Alexandru Jipa, C. Chasman, R. A. Sheetz, R. Planeta, T.F. Thorsteinsen, Christian Holm Christensen, K. Olchanski, Bjørn Hallvard Samset, Gunnar Løvhøiden, Tomasz Kozik, T. Keutgen, Ole Hansen, A Wieloch, C. E. Jørgensen, A. Makeev, Fouad Rami, B. Budick, H. Bøggild, D. Ouerdane, J. B. Natowitz, H. Ito, F. Jundt, J. Brzychczyk, Y. Blyakhman, A. K. Holme, P. Staszel, B. McBreen, Dieter Røhrich, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), BRAHMS, and Heyd, Yvette

Subjects
[PHYS.HPHE] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Nuclear physics, Physics, Nuclear and High Energy Physics, Pseudorapidity, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Hadron, Data analysis, General Physics and Astronomy, Nuclear Experiment, Collision, Charged particle, Characterization (materials science)
Abstract

Charged particle pseudorapidity densities are presented for the 197Au+197Au reaction at $$\sqrt {s_{NN} } = 130$$ . These densities provide an essential characterization of the underlying reactions mechanisms for ultra-relativistic heavy-ion collision. This talk details how the global charged particle yields are measured at BRAHMS and presents some preliminary results from the analysis of data taken during the first year of the RHIC experimental program.

Published
2001

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