1. Gamma-Jet Analysis in Heavy-Ion Collisions Saskia Mioduszewski for the High-p T Working Group

2. Outline Physics Goals What has been done? Current Activities Future

3. Physics Goals To understand “jet suppression”, parton energy loss in medium created in heavy-ion collisions at RHIC  +jet in spin program (S. Trentalange, Thursday) Prompt photon triggers :  +jet no interaction with medium no fragmentation bias: E  ≈ Ejet Probe full volume when measured in combination with hadron+jet correlation measurement (Renk, Wang)  q Background sources of photons (hadronic decays) suppressed in central Au+Au collisions

4. Physics Goals To understand “jet suppression”, parton energy loss in medium created in heavy-ion collisions at RHIC  +jet in spin program (S. Trentalange, Thursday) Prompt photon triggers :  +jet no interaction with medium no fragmentation bias: E  ≈ Ejet Probe full volume when measured in combination with hadron+jet correlation measurement (Renk, Wang)  q

5.  -jet Analysis in Au+Au collisions Thomas Dietel, Quark Matter 2005 STAR “state-of-the-art” result for Au+Au collisions 50  b -1 (2 pb -1 p+p equiv)

6.  -jet in p+p and d+Au Subhasis Chattopadhyay, QM 2006 -- Improved  0 /  separation using shower profile in SMD 00   0 bin mixed bin photon bin

7. (Direct)  -jet in p+p and d+Au Subhasis Chattopadhyay, QM 2006 P T assoc. hadron > 1 GeV/c STAR d+Au Preliminary E t trigger from 8.5GeV/c to 10.5 GeV p+p 2005 ~ 3 pb -1 d+Au: 200  b -1 (80 nb -1 p+p equiv)

8. Inclusive  -jet in p+p and d+Au collisions open: far side closed: near side Near-side and away-side yields of hadrons correlated with a photon trigger Federica Benedosso, QM 2006

9. Inclusive  -jet in Cu+Cu Collisions 860  b -1 (3.4 pb -1 p+p equiv) Et_trg>12GeV 4GeV/c<Pt<12GeV/c Et_trg>18GeV 4GeV/c<Pt<18GeV/c 30-60%10-30%0-10% Ahmed Hamed

10. Run 7 Plans Projected statistics to be 300  b -1 (10 pb -1 p+p equiv)  2.1 Billion MB events sampled + another factor of 2 over Run-4 data from full BEMC coverage  factor of >10 statistical improvement over Run 4 + fully functioning BSMD for shower profile cuts LVL2 Gamma “trigger”  filter LVL0 HT2 events where energy (in 1 or 2 towers) > 7 GeV to express-stream files Ahmed has been working with Jason Webb, Jan Balewski, Chris Perkins, and Jeff Landgraff to get this trigger commissioned for Run 7 “L2GammaAuAu” algorithm taken from the p+p L2Gamma code (written by Jason Webb) Allows us to perform an “express analysis” of  -jets and  0 -jets in Au+Au data Run-6 p+p data as reference (~10 pb -1 – factor of 6 over Run 5)