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Title: Dielectron Continuum Measurements in sqrt(s NN) = 200 GeV Au+Au and Cu+Cu Collisions at PHENIX

Abstract

The dielectron continuum measurement contains a variety of signals, including vector meson decays, hadron Dalitz decays, correlated semi-leptonic heavy flavor decays and direct virtual photon emission. Since electrons and positrons are not affected by the strong force, the resulting signals occur over the full time evolution of the collision. Direct virtual photons are emitted throughout the collision and provide information on the temperature progression of the system. Light vector mesons and correlated heavy flavor production may experience medium modification. Comparison between the PHENIX Au+Au data and the new Cu+Cu data allows an investigation of surface area and volume effects on all dilepton signals. The status of the analysis in Cu+Cu collisions will be presented.

Authors:
 [1];  [2];  [3];  [2];  [3];  [2];  [2];  [4];  [2];  [2];  [3];  [5]
  1. Stony Brook University (SUNY)
  2. ORNL
  3. University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)
  4. University of Tennessee, Knoxville (UTK)
  5. The
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931217
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2006, Shanghai, China, 20061114, 20061120
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLLISIONS; COPPER; ELECTRONS; GOLD; HADRONS; PHOTON EMISSION; PHOTONS; POSITRONS; PRODUCTION; QUARK MATTER; SURFACE AREA; VECTOR MESONS

Citation Formats

Campbell, Sarah, Awes, Terry C, Batsouli, Sotiria, Cianciolo, Vince, Efremenko, Yuri, Read Jr, Kenneth F, Silvermyr, David O, Sorensen, Soren P, Stankus, Paul W, Young, Glenn R, Zhang, Chun, and PHENIX, Collaboration. Dielectron Continuum Measurements in sqrt(sNN) = 200 GeV Au+Au and Cu+Cu Collisions at PHENIX. United States: N. p., 2007. Web.
Campbell, Sarah, Awes, Terry C, Batsouli, Sotiria, Cianciolo, Vince, Efremenko, Yuri, Read Jr, Kenneth F, Silvermyr, David O, Sorensen, Soren P, Stankus, Paul W, Young, Glenn R, Zhang, Chun, & PHENIX, Collaboration. Dielectron Continuum Measurements in sqrt(sNN) = 200 GeV Au+Au and Cu+Cu Collisions at PHENIX. United States.
Campbell, Sarah, Awes, Terry C, Batsouli, Sotiria, Cianciolo, Vince, Efremenko, Yuri, Read Jr, Kenneth F, Silvermyr, David O, Sorensen, Soren P, Stankus, Paul W, Young, Glenn R, Zhang, Chun, and PHENIX, Collaboration. Mon . "Dielectron Continuum Measurements in sqrt(sNN) = 200 GeV Au+Au and Cu+Cu Collisions at PHENIX". United States. doi:.
@article{osti_931217,
title = {Dielectron Continuum Measurements in sqrt(sNN) = 200 GeV Au+Au and Cu+Cu Collisions at PHENIX},
author = {Campbell, Sarah and Awes, Terry C and Batsouli, Sotiria and Cianciolo, Vince and Efremenko, Yuri and Read Jr, Kenneth F and Silvermyr, David O and Sorensen, Soren P and Stankus, Paul W and Young, Glenn R and Zhang, Chun and PHENIX, Collaboration},
abstractNote = {The dielectron continuum measurement contains a variety of signals, including vector meson decays, hadron Dalitz decays, correlated semi-leptonic heavy flavor decays and direct virtual photon emission. Since electrons and positrons are not affected by the strong force, the resulting signals occur over the full time evolution of the collision. Direct virtual photons are emitted throughout the collision and provide information on the temperature progression of the system. Light vector mesons and correlated heavy flavor production may experience medium modification. Comparison between the PHENIX Au+Au data and the new Cu+Cu data allows an investigation of surface area and volume effects on all dilepton signals. The status of the analysis in Cu+Cu collisions will be presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • The {upsilon}{sub 2} and {upsilon}{sub 4} of pions, kaons and protons have been measured by PHENIX in 200 GeV Au+Au collisions up to p{sub T} {approx} 6 GeV/c and 4 GeV/c, respectively. The {upsilon}{sub 4} of all these identified particles have been found to scale with the number of constituent quarks and all these particles have a similar {upsilon}{sub 4}/{upsilon}{sub 2}{sup 2} ratio which is close to 0.9. The scaling behavior of {upsilon}{sub 2} is studied at high p{sub T} and a deviation from the universal scaling is observed for transverse kinetic energy (KE{sub T}/n{sub q}) higher than 1 GeV.
  • The production of deuterons and anti-deuterons in the transverse momentum range 1.1 < p{sub T} < 5.0 GeV/c at mid-rapidity in Au+Au collisions at {radical}S{sub NN} = 200 GeV has been studied by PHENIX for six different centralities. The coalescence of neutrons and protons into deuterons as a function of p{sub T} and N{sub part} has been studied. The large R{sub CP} of deuterons at intermediate p{sub T} is consistent with neutron production having similar centrality dependence to that of protons.
  • A state-of-the-art 3D source imaging technique is used to extract the 3D two-pion source function in central and mid-central Au+Au collisions at {radical}s{sub NN} = 200 GeV. The source function indicates a previously unresolved non-Gaussian tail in the directions of the pion pair transverse momentum (out) and along the beam (long). Model comparisons give robust estimates for several characteristics of the emission source, including its transverse size, its mean proper breakup time {tau} and its emission duration {Delta}{tau}. These estimates are incompatible with the predictions for a first order phase transition. However, they point to significant relative emission times whichmore » could result from a crossover phase transition.« less
  • Recent results indicate that the J/{psi} suppression pattern differs with rapidity showing a larger suppression at forward rapidity. J/{psi} suppression mechanisms based on energy density (such as color screening, interaction with co-movers, etc.) predict the opposite trend. On the other hand, it is expected that more c{bar c} pairs should be available to form quarkonia at mid-rapidity via recombination. Some models provide a way to differentiate J/{psi} production from initially produced c{bar c} pairs and final state recombination of uncorrelated pairs, via the rapidity and transverse momentum dependence of the elliptic flow ({upsilon}{sub 2}). During 2007 data taking at RHIC,more » a large sample of Au+Au collisions at {radical}s{sub NN} = 200 GeV was collected. The statistics has been increased compared to previous 2004 data set, thus allowing a more precise measurement of the J/{psi} production at both mid and forward rapidity. Furthermore, the PHENIX experiment benefited from the addition of a new detector, which improves the reaction plane resolution and allows us to measure the J/{psi} {upsilon}{sub 2}. Comparing this measurement to the positive D-mesons {upsilon}{sub 2} (through non-photonic electron decays) will help constraining the J/{psi} production mechanisms and getting a more precise picture of the proportion of J/{psi} coming from direct production or charm quark coalescence. Details on how the J/{psi} {upsilon}{sub 2} is measured at mid-rapidity rapidities are presented. The J/{psi} {upsilon}{sub 2} as a function of transverse momentum are compared to existing models.« less