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Measurements of J/$ψ$ yields at forward and mid-rapidity in d+Au, Cu+Cu and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV by PHENIX at RHIC  [PDF]
VN Tram,for the PHENIX collaboration
Physics , 2006,
Abstract: The J/$\psi$ yields in heavy ion collisions are expected to be a promising probe of deconfined matter, since theoretical models predict that the J/$\psi$ production could be strongly suppressed due to color screening effect in a Quark Gluon Plasma. In addition, one of the interesting predictions that has emerged recently is the J/$\psi$ enhancement at RHIC energy via competing mechanisms such as recombination. The PHENIX collaboration has measured J/$\psi$ production via its decay into lepton pairs in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 200 GeV. The nuclear modification factor $R_{\rm AA}$ for the ${\rm J}/\psi$ is obtained by comparing Au+Au or Cu+Cu collisions to p+p collisions. The $R_{\rm AA}$ dependences on centrality, transverse momentum and rapidity are presented both at forward rapidity ($1.2<|y|<2.2$) using ${\rm J}/\psi\to\mu^+\mu^-$ and at mid rapidity ($|y|<0.35$) using ${\rm J}/\psi\to e^+e^-$. These preliminary results are compared to cold nuclear matter expectations derived from PHENIX d+Au measurements, to results obtained by NA50 experiment and to various theoretical models.
$J/Ψ$ production in $Cu+Cu$ and $Au+Au$ collisions measured by PHENIX at RHIC  [PDF]
Andry M. Rakotozafindrabe
Physics , 2006, DOI: 10.1088/0954-3899/32/12/S69
Abstract: PHENIX preliminary results on the $J/\Psi$ production in $Cu+Cu$ and $Au+Au$ collisions at $\sqrt{s_{NN}}=200$ GeV are presented. They are compared to results from lower energy experiments NA50 and NA60 at CERN SPS and to expectations from various theoretical models.
Anomalous φMeson Suppression in Au+Au Collisions at \sqrt{s_{NN}}=200 GeV Measured by the PHENIX Experiment at RHIC  [PDF]
Maxim Naglis,for the PHENIX collaboration
Physics , 2009, DOI: 10.1016/j.nuclphysa.2009.10.068
Abstract: The PHENIX experiment at RHIC has measured the \phi-meson production at mid-rapidity in p+p, d+Au, Cu+Cu and Au+Au collisions at \sqrt{s_{NN}}=200 GeV via the K^+K^- decay mode. The transverse momentum spectra of the \phi-meson and the nuclear modification factor as a function of centrality are reviewed here.
$J/ψ$ production in Au+Au collisions at RHIC and the nuclear absorption  [PDF]
A. K. Chaudhuri
Physics , 2003, DOI: 10.1103/PhysRevC.74.044907
Abstract: It is shown that a QCD based nuclear absorption model, with few parameters fixed to reproduce experimental $J/\psi$ yield in 200 GeV pp/pA and 450 GeV pA collisions can explain the preliminary PHENIX data on the centrality dependence of $J/\psi$ suppression in Cu+Cu collisions at RHIC energy, $\sqrt{s_{NN}}$=200 GeV. However, the model does not give satisfactory description to the preliminary PHENIX data on the centrality dependence of $J/\psi$ suppression in Au+Au collisions. The analysis suggest that in Au+Au collisions, $J/\psi$ are suppressed in a medium unlike the medium produced in SPS energy nuclear collisions or in RHIC energy Cu+Cu collisions.
System size, energy, centrality and pseudorapidity dependence of charged-particle density in Au+Au and Cu+Cu collisions at RHIC  [PDF]
PHOBOS Collaboration,G. I. Veres,B. Alver,B. B. Back,M. D. Baker,M. Ballintijn,D. S. Barton,R. R. Betts,A. A. Bickley,R. Bindel,W. Busza,A. Carroll,Z. Chai,V. Chetluru,M. P. Decowski,E. García,T. Gburek,N. George,K. Gulbrandsen,C. Halliwell,J. Hamblen,I. Harnarine,M. Hauer,C. Henderson,D. J. Hofman,R. S. Hollis,R. Ho?yński,B. Holzman,A. Iordanova,E. Johnson,J. L. Kane,N. Khan,P. Kulinich,C. M. Kuo,W. Li,W. T. Lin,C. Loizides,S. Manly,A. C. Mignerey,R. Nouicer,A. Olszewski,R. Pak,C. Reed,E. Richardson,C. Roland,G. Roland,J. Sagerer,H. Seals,I. Sedykh,C. E. Smith,M. A. Stankiewicz,P. Steinberg,G. S. F. Stephans,A. Sukhanov,A. Szostak,M. B. Tonjes,A. Trzupek,C. Vale,G. J. van Nieuwenhuizen,S. S. Vaurynovich,R. Verdier,P. Walters,E. Wenger,D. Willhelm,F. L. H. Wolfs,B. Wosiek,K. Wo?niak,S. Wyngaardt,B. Wys?ouch
Physics , 2008, DOI: 10.1007/s12648-011-0135-2
Abstract: Charged particle pseudorapidity distributions are presented from the PHOBOS experiment at RHIC, measured in Au+Au and Cu+Cu collisions at sqrt{s_NN}=19.6, 22.4, 62.4, 130 and 200 GeV, as a function of collision centrality. The presentation includes the recently analyzed Cu+Cu data at 22.4 GeV. The measurements were made by the same detector setup over a broad range in pseudorapidity, |eta|<5.4, allowing for a reliable systematic study of particle production as a function of energy, centrality and system size. Comparing Cu+Cu and Au+Au results, we find that the total number of produced charged particles and the overall shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants, N_part. Detailed comparisons reveal that the matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of eta is better for the same N_part/2A value than for the same N_part value, where A denotes the mass number. In other words, it is the geometry of the nuclear overlap zone, rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence.
Measurements of high-pT neutral mesons in $\sqrt{s_{NN}}$ = 200 GeV Au+Au and Cu+Cu Collisions at RHIC-PHENIX  [PDF]
Tadaaki Isobe
Physics , 2006, DOI: 10.1063/1.2220186
Abstract: Measurements from the RHIC experiments show strong suppression of high-pT hadrons in central Au+Au collisions. The PHENIX experiment has observed strong suppression of $\pi^0$ and charged hadron yields in central Au+Au collisions for pT > 5 GeV/c regardless of pT and particle species. The observed suppression is interpreted in terms of energy loss of quarks in a high-density medium. The PHENIX Year-4 Au+Au measurements have extended the pT reach of the $\pi^0$ spectra to 20 GeV/c. And the PHENIX Year-5 Cu+Cu measurements performed for the study of particle production in a lighter system and they can provide the system-size dependence of the suppression. The suppression patterns of $\pi^0$/$\eta$ at high pT are presented for each collision system (Au+Au/Cu+Cu).
PHENIX results on jpsi production in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV  [PDF]
H. Pereira Da Costa,for the PHENIX collaboration
Physics , 2005, DOI: 10.1016/j.nuclphysa.2006.06.129
Abstract: Heavy quarkonia production is predicted to be sensitive to the formation of the quark gluon plasma in relativistic heavy ion collisions via competing mechanisms such as color screening and/or quark recombination. During 2004 and 2005 RHIC data taking periods, the PHENIX collaboration has measured jpsi decay into lepton pairs both at mid and forward rapidity in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV. We present the jpsi nuclear modification factor and the $\jpsi$ mean square transverse momentum as a function of the collision centrality for both systems, as well as the rapidity dependence of the jpsi yield for different centrality classes. It is compared to different theoretical predictions. All Au+Au and Cu+Cu results shown here are preliminary.
Search for the onset of baryon anomaly at RHIC-PHENIX  [PDF]
Tatsuya Chujo
Physics , 2006, DOI: 10.1140/epjc/s10052-006-0088-3
Abstract: The baryon production mechanism at the intermediate $p_T$ (2 - 5 GeV/$c$) at RHIC is still not well understood. The beam energy scan data in Cu+Cu and Au+Au systems at RHIC may provide us a further insight on the origin of the baryon anomaly and its evolution as a function of $\sqrt{s_{NN}}$. In 2005 RHIC physics program, the PHENIX experiment accumulated the first intensive low beam energy data in Cu+Cu collisions. We present the preliminary results of identified charged hadron spectra in Cu+Cu at $\sqrt{s_{NN}}$ = 22.5 and 62.4 GeV using the PHENIX detector. The centrality and beam energy dependences of (anti)proton to pion ratios and the nuclear modification factors for charged pions and (anti)protons are presented.
$J/ψ$ production in Au+Au/Cu+Cu collisions at $\sqrt{s}_{NN}$=200 GeV and the threshold model  [PDF]
A. K. Chaudhuri
Physics , 2006, DOI: 10.1103/PhysRevC.75.044902
Abstract: Using the QGP motivated threshold model, where all the $J/\psi$'s are suppressed above a threshold density, we have analyzed the preliminary PHENIX data on the centrality dependence of nuclear modification factor for $J/\psi$'s in Cu+Cu and in Au+Au collisions, at RHIC energy, $\sqrt{s}_{NN}$=200 GeV. Centrality dependence of $J/\psi$ suppression in Au+Au collisions are well explained in the model for threshold densities in ranges of 3.6-3.7 $fm^{-2}$. $J/\psi$ suppression in Cu+Cu collisions on the other hand are not explained in the model.
The PHENIX Potential in the Search for the QCD Critical Point  [PDF]
J. T. Mitchell
Physics , 2007,
Abstract: With the measurement of several observables at SPS energies that demonstrate non-monotonic behavior as a function of centrality and $\sqrt{s_{NN}}$, there is growing interest in pursuing a scan of relativistic heavy ion collisions at low energies at the Relativistic Heavy Ion Collider. The capabilities of the PHENIX experiment to take quality measurements at low RHIC energies is described and directly demonstrated with analyses of Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 GeV and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 22.5 GeV. The contribution of upgrades to the PHENIX detector in the upcoming years will also be discussed in the context of a low energy RHIC run.
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