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Träfflista för sökning "WFRF:(Isenhower L.) srt2:(2003-2004)"

Sökning: WFRF:(Isenhower L.) > (2003-2004)

  • Resultat 1-9 av 9
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1.
  • Adler, SS, et al. (författare)
  • Suppressed pi(0) production at large transverse momentum in central Au plus Au collisions at root s(NN)=200 GeV
  • 2003
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 91:7: 072301
  • Tidskriftsartikel (refereegranskat)abstract
    • Transverse momentum spectra of neutral pions in the range 1<p(T)<10 GeV/c have been measured at midrapidity by the PHENIX experiment at BNL RHIC in Au+Au collisions at roots(NN)=200 GeV. The pi(0) multiplicity in central reactions is significantly below the yields measured at the same roots(NN) in peripheral Au+Au and p+p reactions scaled by the number of nucleon-nucleon collisions. For the most central bin, the suppression factor is similar to2.5 at p(T)=2 GeV/c and increases to similar to4-5 at p(T)approximate to4 GeV/c. At larger p(T), the suppression remains constant within errors. The deficit is already apparent in semiperipheral reactions and increases smoothly with centrality.
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2.
  • Adcox, K, et al. (författare)
  • PHENIX detector overview
  • 2003
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - Elsevier. - 0167-5087. ; 499:2-3, s. 469-479
  • Tidskriftsartikel (refereegranskat)abstract
    • The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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3.
  • Adler, SS, et al. (författare)
  • Bose-Einstein correlations of charged pion pairs in Au+Au collisions at root(NN)-N-s = 200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 93:15
  • Tidskriftsartikel (refereegranskat)abstract
    • Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au+Au collisions at roots(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R-out/R-side is within 0.8-1.1 for 0.25<<k(T)><1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N-part(1/3), and R-out/R-side for <k(T)>similar to0.45 GeV/c is approximately constant at unity as a function of centrality.
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4.
  • Adler, SS, et al. (författare)
  • Elliptic flow of identified hadrons in Au+Au collisions at root s(NN)=200 GeV
  • 2003
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 91:18: 182301
  • Tidskriftsartikel (refereegranskat)abstract
    • The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at roots(NN)=200 GeV for identified and inclusive charged particle production at central rapidities (eta<0.35) with respect to the reaction plane defined at high rapidities (eta=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.
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5.
  • Adler, SS, et al. (författare)
  • J/psi production from proton-proton collisions at root s=200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 92:5
  • Tidskriftsartikel (refereegranskat)abstract
    • J/psi production has been measured in proton-proton collisions at roots=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 4.0+/-0.6(stat)+/-0.6(syst)+/-0.4(abs) mub. The mean transverse momentum is 1.80+/-0.23(stat)+/-0.16(syst) GeV/c.
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6.
  • Adler, SS, et al. (författare)
  • J/psi production in Au-Au collisions at root s(NN)=200 GeV
  • 2004
  • Ingår i: Physical Review C (Nuclear Physics). - American Physical Society. - 0556-2813. ; 69:1
  • Tidskriftsartikel (refereegranskat)abstract
    • First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/psi's measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au-Au reactions at roots(NN) = 200 GeV is analyzed as a function of collision centrality. For this analysis we have studied 49.3x10(6) minimum bias Au-Au reactions. We present the J/psi invariant yield dN/dy for peripheral and midcentral reactions. For the most central collisions where we observe no signal above background, we quote 90% confidence level upper limits. We compare these results with our J/psi measurement from proton-proton reactions at the same energy. We find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.
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7.
  • Adler, SS, et al. (författare)
  • Midrapidity neutral-pion production in proton-proton collisions at root s 200 GeV
  • 2003
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 91:24: 241803
  • Tidskriftsartikel (refereegranskat)abstract
    • The invariant differential cross section for inclusive neutral-pion production in p+p collisions at roots=200 GeV has been measured at midrapidity (eta<0.35) over the range 1<p(T)less than or similar to14 GeV/c by the PHENIX experiment at the Relativistic Heavy Ion Collider. Predictions of next-to-leading order perturbative QCD calculations are consistent with these measurements. The precision of our result is sufficient to differentiate between prevailing gluon-to-pion fragmentation functions.
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8.
  • Adler, SS, et al. (författare)
  • Scaling properties of proton and antiproton production in root s(NN)=200 GeV Au+Au collisions
  • 2003
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 91:17: 172301
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at rootS(NN)=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5<p(T)<4.5 GeV/c) a significant fraction of all produced particles are protons and antiprotons. They show a centrality-scaling behavior different from that of pions. The (p) over bar/pi and p/pi ratios are enhanced compared to peripheral Au+Au, p+p, and e(+)e(-) collisions. This enhancement is limited to p(T)<5 GeV/c as deduced from the ratio of charged hadrons to pi(0) measured in the range 1.5<p(T)<9 GeV/c.
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9.
  • Adler, SS, et al. (författare)
  • Double helicity asymmetry in inclusive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 93:20: 202002
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at roots=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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