1. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 High P T Physics in ALICE LHC Alice Dedicated “general purpose” Heavy Ion experiment at LHC

2. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 ALICE Overview

3. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 ALICE Set-up HMPID Muon Arm TRD PHOS PMD ITS TOF TPC Size: 16 x 26 meters Weight: 10,000 tons EMCal

4. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 ALICE Detectors & Acceptance central barrel -0.9 <  < 0.9  = 2  tracking, PID (TPC/ITS/ToF) single arm RICH (HMPID) single arm e.m. cal (PHOS) jet calorimeter (proposed EMCal) forward muon arm 2.4 <  < 4 absorber, 3 T-m dipole magnet 10 tracking + 4 trigger chambers multiplicity detectors -5.4 <  < 3 including photon counting in PMD trigger & timing detectors 6 Zero Degree Calorimeters T0: ring of quartz window PMT's V0: ring of scint. Paddles (charged particles) µ arm EMCal

5. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Global tracking (ITS-TPC-TRD) + dE/dx (low p T + relativ. rise) + TOF, HMPID, PHOS, … Invariant mass, topological reconstruction Particle Identification in ALICE Pb-Pb Decay particles  10-15 GeV , K, p 0.1- 0.15  50 GeV p T range for PID in 10 7 central Pb-Pb and 10 9 min. bias pp

6. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

7. ALICE EMCal 10+1/2+1/2=11 super-modules 8 SM from US 3 SM from France, Italy Lead-scintillator sampling calorimeter  = 1.4,  =110 o Shashlik geometry, APD photosensor ~13K towers (  x  ~ 0.014 x 0.014) Energy resolution  15%/√E + 2% over-takes tracking above 30 GeV  o /  discrimination to p T ~ 30 GeV Approved by LHCC 9/28/06 Allows Jet Measurements with ALICE

8. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 US Involvement in ALICE ALICE-USA Collaboration 12 DOE-supported research institutions: Creighton, Houston, Kent State, LBNL, LLNL, Michigan State, Oak Ridge, Purdue, Tennessee, Texas, Wayne State, and Yale ALICE-USA Primary Focus Investigate medium modification of partonic energy loss – “jet quenching” Investigate response of medium to large energy depositions Ensure the EMCal is constructed, operational in ALICE; extract EMCal physics ALICE-USA Equip. Proposal to DOE for Major Fraction of ALICE EMCal Construct 8 of 11 super-modules of EMCal for ALICE Italy and France proposing to construct 3 CERN LHC Committee approved EMCal for installation in ALICE Passed CDs-0,1 Reviews of DOE

9. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 LHC Heavy Ions & ALICE Physics Overview

10. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Heavy Ion Physics at the LHC Soft Physics at LHC – smooth extrapolation from SPS  RHIC  LHC? expansion will be different spectra, T chem & T kin,, particle ratios, v 2, HBT, strange/charm particles, resonances Hard Probes at LHC – significant increase in hard cross sections   hard /  total  ~ 2% at SPS 50% at RHIC 98% at LHC “real” jets, large p T processes abundance of heavy flavors probe early times, calculable  precision studies!  bb (LHC ) ~ 100  bb (RHIC)  cc (LHC) ~ 10  cc (RHIC)

11. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 ALICE Measurements in a Nutshell Soft Probes – “ala RHIC” (STAR + PHENIX) Expansion dynamics different from RHIC due to timescales, densities All soft physics measurements as at RHIC so far (+ extended PID) Day 1 physics + Hard Probes – Jet Quenching Jets,  pi-zeros, leading particles to large p T,  jet Hard Probes – Heavy Quarks Displaced vertices (D o  K -  +) from TPC/ITS Electrons in Transition Radiation Detector (TRD) Hard Probes – Quarkonia J/ , ,  ’ (excellent),  ’’(2-3 yrs),  ’ (…)

12. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 High P T Physics with ALICE EMCal

13. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Physics with the ALICE EMCal Utilize Initial Hard Parton Scattering High energy jets, photons and heavy flavors  requires EMCal and triggering Exploit large kinematic range of jets at LHC Measure jet structure & medium-induced jet modification Investigate energy loss mechanism with quark-tagged jets (heavy flavor decays) gluon jets (light hadron leading)  – jet coincidences Low energy particles correlated with trigger or quenched jet  requires ALICE acceptance, robust tracking, & PID to low/high p T Investigate energy propagation in medium to determine medium properties

14. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Capabilities of ALICE with EMCal EMCal improves detector capabilities: - Fast trigger ~10 -100 enhancement of jets - Improves jet reconstruction (plus TPC) - Good   discrimination increases coverage - Good electron/hadron discrimination EMCal extends the physics of ALICE: 10 4 / year in minbias Pb+Pb: inclusive jets: E T ~ 200 GeV dijets: E T ~ 170 GeV   : p T ~ 75 GeV inclusive  : p T ~ 45 GeV inclusive e: p T ~ 30 GeV Thanks – P.Jacobs

15. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Start of Detailed “Tomography” of the QGP F QGP (  g QGP ) = f initial (√s, A 1 +A 2, b, x 1, x 2, Q 2 )  f QGP (p T ,y ,  ,p T jet,y jet,  jet, flavor jet,  flow ) “jet flow plane  /parton parton near-side Renk, hep-ph/0602045 Di-hadrons penetrate core! Renk, hep-ph/0602045 near-side Trigger hadrons come from near-side surface

16. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Di-Hadron Correlations at RHIC “jet Data: STAR, nucl-ex/0510002; pQCD E-loss Model + expansion: Renk, hep-ph/0602045 No near-side sensitivity to medium Slight away-side sensitivity to medium More extensive di-hadron measurements from PHENIX (hep-ex/0605039) and STAR (nucl-ex/0510002): Di-hadron fragmentation functions exhibit only a weak sensitivity to medium!  - jet and better jet energy (full jet) measurements necessary

17. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Tagging Jets with Photons Strategy (event by event): R Thanks - Gustavo Conesa Balbastre – INFN Frascati IP EMCal TPC R Reconstruct the jet : Particles around leading with p T > 0.5 GeV/c, inside a cone of R = 0.3. 2 configurations: charged and neutral hadrons (TPC+EMCAL) and charged only (TPC).  min  max Search for leading particle :   -  leading ~ 180º E leading > 0.1 E  leading PHOS Search for identified prompt photon (in PHOS) with largest p T (E  > 20 GeV)

18. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Jet Reconstruction Fragmentation: p(hadron) p (parton) z = =  (  2 +  2 ) Large background in RHI Collisions – must limit jet cone radius R, track p T cut  only measure fraction of parton energy - calibrate

19. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Soft Background in Jet Cones Cone radius R=√(Δη 2 +ΔΦ 2 ) Large cone radius  large background Radius cut of.4 + p T cut  lowers background  > 80% of E jet

20. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Medium Modification of Jet Fragmentation Fragmentation along jet axis: z = p hadron / p parton Introduce  = ln(E jet / p hadron ) ~ ln (1/z): jet direction z Sensitivity to p T = 2.0 0.7 GeV/c A. Morsche (ALICE)

21. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Medium Modification of Jet Fragmentation Fragmentation along jet axis: z = p hadron / p parton Introduce  = ln(E jet / p hadron ) ~ ln (1/z): jet direction z Thanks – Joern Putschke N. Borghini, U. Wiedemann hep-ph/0506218 # particles with low z increases # particles with high z decreases p T hadron ~2 GeV

22. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Ideal Case for Pb + Pb and p + p q ^

23. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Jet Quenching in ALICE with EMCAL in 1 Year

24. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 ALICE Jet Trigger Enhancement Jet trigger Includes acceptance, efficiency, dead time, energy resolution Compare central Pb+Pb to reference measurements in Pb+Pb peripheral: vary system size and shape p+A: cold nuclear matter effects p+p (14 TeV): no nuclear effects, but different energy p+p (5.5 TeV): ideal reference, but limited statistics Systematic study involves all reference systems

25. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 ALICE Jet Trigger Yields in an LHC Pb + Pb Year Jet yield in 20 GeV bin Large gains due to jet trigger Large variation in statistical reach for different reference systems

26. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Summary ALICE - versatile, general purpose heavy ion detector at LHC will contribute significantly to understanding of HI physics - soft physics - high p T physics ALICE EMCal provides significant high p T and jet physics measures and triggers on jets, photons, pi-zeros heavy quark jet tags triggered jets  response of medium in lower p T sector Work continues to develop best jet algorithm for heavy ions deal with background, jet-splitting & jet-merging develop heavy flavor (quark) tag algorithms Need detailed theoretical/simulation approach at parton level

27. John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007 Special thanks for contributors: Joern Putschke Gustavo Conesa Balbastre Marco van Leeuwen Peter Jacobs Matt Lamont Andreas Morsche