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High P T Physics in ALICE

Alice. Dedicated “general purpose” Heavy Ion experiment at LHC. High P T Physics in ALICE. LHC. ALICE Overview. ALICE Set-up. TOF. TRD. HMPID. EMCal. ITS. PMD. Muon Arm. PHOS. Size : 16 x 26 meters Weight : 10,000 tons. TPC. (charged particles). EMCal. µ arm.

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High P T Physics in ALICE

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

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

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

  4. (charged particles) EMCal µ arm ALICE Detectors & Acceptance central barrel -0.9 < h < 0.9 • Df = 2p tracking, PID (TPC/ITS/ToF) • single arm RICH (HMPID) • single arm e.m. cal (PHOS) • jet calorimeter (proposed EMCal) forward muon arm 2.4 < h < 4 • absorber, 3 T-m dipole magnet10 tracking + 4 trigger chambers multiplicity detectors -5.4 < h < 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 John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

  5. Particle Identification in ALICE Global tracking (ITS-TPC-TRD) + dE/dx (low pT + relativ. rise) + TOF, HMPID, PHOS, … Invariant mass, topological reconstruction pT range for PID in 107 central Pb-Pb and 109 min. bias pp p, K, p 0.1- 0.15  50 GeV Decay particles 10-15 GeV Pb-Pb John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

  7. ALICE EMCal Approved by LHCC 9/28/06 • 10+1/2+1/2=11 super-modules • 8 SM from US • 3 SM from France, Italy Allows Jet Measurements with ALICE Lead-scintillator sampling calorimeter Dh = 1.4, Df=110o Shashlik geometry, APD photosensor ~13K towers (DhxDf ~ 0.014 x 0.014) Energy resolution  15%/√E + 2% over-takes tracking above 30 GeV po/g discrimination to pT ~ 30 GeV John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

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

  10. sbb (LHC ) ~ 100 sbb (RHIC) scc (LHC) ~ 10 scc (RHIC) Heavy Ion Physics at the LHC Soft Physics at LHC – • smooth extrapolation from SPS  RHIC LHC? • expansion will be different • spectra, Tchem & Tkin, , particle ratios, v2, HBT, • strange/charm particles, resonances Hard Probes at LHC – • significant increase in hard cross sections •  shard /stotal~ 2% at SPS • 50% at RHIC • 98% at LHC • “real” jets, large pT processes • abundance of heavy flavors • probe early times, calculable  precision studies! John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

  11. 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, g , pi-zeros, leading particles to large pT , g + jet Hard Probes – Heavy Quarks • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) Hard Probes – Quarkonia • J/y, , ’ (excellent),’’(2-3 yrs),y’ (…) John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

  13. 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) • g – jet coincidences • Low energy particles correlated with trigger or quenched jet •  requires ALICE acceptance, robust tracking, & PID to low/high pT • Investigate energy propagation in medium to determine medium properties John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

  14. Capabilities of ALICE with EMCal EMCal improves detector capabilities: - Fast trigger ~10 -100 enhancement of jets - Improves jet reconstruction (plus TPC) - Goodg/p0discrimination increases coverage - Good electron/hadron discrimination • EMCal extends the physics of ALICE: • 104 / year in minbias Pb+Pb: • inclusive jets: ET ~ 200 GeV • dijets: ET ~ 170 GeV • p0: pT ~ 75 GeV • inclusive g: pT ~ 45 GeV • inclusive e: pT ~ 30 GeV Thanks – P.Jacobs John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

  15. g/parton Renk, hep-ph/0602045 Renk, hep-ph/0602045 near-side near-side parton Trigger hadronscome fromnear-side surface Di-hadrons penetrate core! flow plane Start of Detailed “Tomography” of the QGP FQGP (rgQGP) =finitial (√s, A1+A2, b, x1, x2, Q2)  fQGP (pTg,yg ,fg ,pT jet,y jet ,f jet, flavor jet, f flow) “jet John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

  16. Di-Hadron Correlations at RHIC Data: STAR, nucl-ex/0510002; pQCD E-loss Model + expansion: Renk, hep-ph/0602045 Slight away-side sensitivity to medium No near-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 g - jet and better jet energy (full jet) measurements necessary John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

  18. Fragmentation: p(hadron) p (parton) z = Jet Reconstruction =  (Df2 + Dh2 ) Large background in RHI Collisions – must limit jet cone radius R, track pT cut  only measure fraction of parton energy - calibrate John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

  19. Large cone radius  large background Radius cut of .4 + pT cut  lowers background  > 80% of Ejet Cone radius R=√(Δη2+ΔΦ2) Soft Background in Jet Cones John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

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

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

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

  24. ALICE Jet Trigger Enhancement Jet trigger • 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 Includes acceptance, efficiency, dead time, energy resolution John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

  26. Summary • ALICE - versatile, general purpose heavy ion detector at LHC • will contribute significantly to understanding of HI physics • - soft physics • - high pT physics • ALICE EMCal provides significant high pT and jet physics • measures and triggers on jets, photons, pi-zeros • heavy quark jet tags • triggered jets  response of medium in lower pT 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 John Harris (Yale) Winter Workshop on Nuclear Dynamics, Big Sky, MT, 12 – 17 Feb. 2007

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

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