1. |
- Adler, SS, et al.
(author)
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Double helicity asymmetry in inclusive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
- 2004
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In: Physical Review Letters. - 1079-7114. ; 93:20: 202002
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Journal article (peer-reviewed)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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2. |
- Adler, SS, et al.
(author)
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Elliptic flow of identified hadrons in Au+Au collisions at root s(NN)=200 GeV
- 2003
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In: Physical Review Letters. - 1079-7114. ; 91:18: 182301
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Journal article (peer-reviewed)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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3. |
- Adler, SS, et al.
(author)
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Bose-Einstein correlations of charged pion pairs in Au+Au collisions at root(NN)-N-s = 200 GeV
- 2004
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In: Physical Review Letters. - 1079-7114. ; 93:15
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Journal article (peer-reviewed)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<<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 similar to0.45 GeV/c is approximately constant at unity as a function of centrality.
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4. |
- Adler, SS, et al.
(author)
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J/psi production from proton-proton collisions at root s=200 GeV
- 2004
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In: Physical Review Letters. - 1079-7114. ; 92:5
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Journal article (peer-reviewed)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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5. |
- Adler, SS, et al.
(author)
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J/psi production in Au-Au collisions at root s(NN)=200 GeV
- 2004
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:1
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Journal article (peer-reviewed)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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6. |
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7. |
- Adler, SS, et al.
(author)
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Scaling properties of proton and antiproton production in root s(NN)=200 GeV Au+Au collisions
- 2003
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In: Physical Review Letters. - 1079-7114. ; 91:17: 172301
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Journal article (peer-reviewed)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
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8. |
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9. |
- Adcox, K, et al.
(author)
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Net charge fluctuations in Au+Au interactions root s(NN)=130 GeV
- 2002
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In: Physical Review Letters. - 1079-7114. ; 89
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Journal article (peer-reviewed)abstract
- Data from Au+ Au interactions at s(NN)=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.
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10. |
- Adcox, K, et al.
(author)
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Centrality dependence of the high (PT) charged hadron suppression in Au+Au collisions at root s(NN)=130 GeV
- 2003
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 561:1-2, s. 82-92
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Journal article (peer-reviewed)abstract
- PHENIX has measured the centrality dependence of charged hadron p(T) spectra from Au +An collisions at root(s)NN = 130 GeV The truncated mean p(T) decreases with centrality for p(T) > 2 GeV/c, indicating an apparent reduction of the contribution from hard scattering to high p(T) hadrdn production. For central collisions the yield at high p(T) is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p + p, data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e., for collisions with less than similar to140 participating nucleons. The observed p(T) and centrality dependence is consistent with the particle production predicted by models including hard scattering and subsequent energy loss of the scattered partons in the dense matter created in the collisions. (C) 2003 Published by Elsevier Science B.V.
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