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-jet measurements Table of Contents: Motivation Preliminary QA of -trigger Data Shower Shape Analysis Experimental Challenges Summary -trigger in Run 2007 Texas A&M Group Ahmed M. Hamed BNL 10-17-07
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Motivation Why -jet measurements? Single Particle Spectra-R AA Mid-rapidity Statistical Method Heavy quarks suppress as much as light quarks in the medium. R AA exhibits only very limited sensitivity to the properties of the medium. More differential observable is needed.
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? Near-side: p+p, d+Au, Au+Au is similar. Back-to-back: Au+Au strongly suppressed relative to p+p and d+Au. Suppression of the back- to-back correlation in central Au+Au is a final-state effect Motivation Why -jet measurements? Jet-like azimuthal correlations Surface bias for the trigger particle. Trigger particle with no surface bias is required for better calibration of the away-side jet. Trigger particle with no surface bias is required for better calibration of the away-side jet. Texas A&M Group Ahmed M. Hamed BNL 10-19-07
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Better understanding for the energy loss mechanism! Elliptic flow. oDirect Photons: Gamma-charged hadrons correlation. Four multipurpose experiments (BRAHMS, PHENIX, PHOBOS, STAR) Empirical lines of evidence: Energy density well beyond critical value. Large elliptic flow. Jet quenching. dAu control experiment. Interpreted in terms of a strongly coupled QGP and a new QCD state (?) Color Glass Condensate Required: Challengeable measurements! Doesn’t couple to the medium. QGP thermal photons. Test for binary scaling for hard process. Motivation Why -jet measurements? Summary Texas A&M Group Ahmed M. Hamed BNL 10-19-07
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Motivation Why -jet measurements? LO Direct photons Bremsstrahlung fragmentation component direct component Decay photons hard: thermal: schematic view Calibrated probe of the QGP – at LO. No Surface Bias Hard process Possible discriminator for quark/gluon jet at LO. oGamma-charged hadrons correlation. Texas A&M Group Ahmed M. Hamed BNL 10-19-07
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Experimental Challenges Is it possible to measure? 0 – spectra are suppressed by a factor of ~5 relative to the scaled p+p collisions. Pythia v6.131 event generator pp-collisions at √s=200 GeV, |η|<1 (STAR acceptance) The away-side in di-jet production is more suppressed. Background sources of direct photons suppressed in medium. Texas A&M Group Ahmed M. Hamed BNL 10-19-07 In medium:
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Inclusive - jet in Au+Au at s=200GeV Thomas Dietel Quark Matter 2005 SIMULATION (pp) Away-side decreases with increasing centrality. Decrease in near-side due to the increased fraction of prompt photons. Need / 0 discrimination. STAR Preliminary Simulation shows no associated particles in -charged correlation. Experimental Challenges Is it possible to measure? Texas A&M Group Ahmed M. Hamed BNL 10-19-07 0 simulation photon simulation
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Bin Mixed Bin S. Chattopadhyay Quark Matter 2006 Reduction in near angle peak towards photon Bin. Effect is more prominent for larger E t trigger. Away-side yield is reduced. Experimental Challenges Is it possible to measure?
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Experimental Challenges Is it possible to measure? cucu2005 STAR Preliminary
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Experimental Challenges Is it possible to measure?
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-plane -plane High energy core. Low energy halo. Electromagnetic transverse shower characteristics 0 DECAY KINEMATICS Towers (~0.05x~0.05), Strips (~0.007x~0.007), d ~2.2m at =0, l~2.93m. min = 2 Sin –1 (m Inv /E), ~10 -17 s Texas A&M Group Ahmed M. Hamed BNL 10-19-07 0 ’s p T (GeV/c) Opening angle(rad) Experimental Challenges Is it possible to measure?
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L2 Gamma Trigger in Run 2007 Texas A&M Group Ahmed M. Hamed BNL 10-19-07 o Tower threshold ET=5.76 [GeV] o Cluster threshold ET= 7.44 [GeV] o Cluster size is one or two tower. L2gammaResult Contains: phi_bin,eta_bin, tower E T, and Cluster E T. ~1.2M events. ~50% Reversed Full Field. http://online.star.bnl.gov/L2gamma2007/l2gamma2007_bemc/ All runs after 8143* are in the reversed full field configuration.
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Preliminary QA of -trigger Data- BEMC
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Preliminary QA of -trigger Data- BEMC
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Preliminary QA of -trigger Data- BSMD saturation
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Preliminary QA of -trigger Data- BEMC 0
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Tower_Id !=1433,3407,3711,3720,3840 Preliminary QA of -trigger Data- Hot Towers
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Showers shape Analysis Real data vs. Single particle simulation Texas A&M Group Ahmed M. Hamed BNL 10-19-07 pp@2006 Shower shape is wider in real data than in simulation!
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Shower Shape Analysis Real data vs. pythia Texas A&M Group Ahmed M. Hamed BNL 10-19-07 pp@2006
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Shower Shape Analysis Real data vs. pythia o Pythia doesn ’ t reproduce the shower shape even with saturation! Saturation parameters-Eta [700,70,10] Saturation parameters-Phi [700,70,10] o In phi-plane the shower shape is closer to the real data than in eta.
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Shower Shape Analysis 0 vs. electron Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Saturation parameters-Eta [700,70,10] Saturation parameters-Phi [700,70,10]
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Shower Shape Analysis 0 vs. electron
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Shower Shape Analysis 0 vs. electron
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Shower Shape Analysis 0 vs. electron
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Shower Shape Analysis 0 vs. electron
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Summary Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Embedding request is still under processed. -jet measurements are very promising tool for better understanding of the medium. Shower shape study is required for direct photons identification. Promising study for transverse shower profile is undertaken.
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Texas A&M Group Ahmed M. Hamed BNL 10-19-07 Motivation BEMC- 0 AuAu@2007
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