ALICE – USA Progress Update T.M. Cormier Germantown, May 29, 2003

1. ALICE – USA Progress Update T.M. Cormier Germantown, May 29, 2003

2. Outline Collaboration The ALICE Detector and the Proposed Physics Physics Performance Studies Cost and Schedule and the Critical Path

3. Creighton University Kent State University Lawrence Berkeley National Laboratory Michigan State University Oak Ridge National Laboratory Purdue University The Ohio State University University of California, Berkeley University of California, Davis University of California, Los Angeles University of Houston University of Tennessee Vanderbilt University Wayne State University

4. Ph.D. Manpower Profile Student Profile

5. The Collaboration…… • Broad range of physics interests that span the entire ALICE physics program • Existing collaboration members are recognized experts across the spectrum of heavy ion physicsfrom BEVALAC to RHIC–HBT, Strangeness, Collective Flow, Direct and Thermal Photons, E-by-E, High PT, etc. • The collaboration expects to participate in all these areas at ALICE but as last time, the presentation focuses on high Q2 processes as a subset of our entire program

6. Simulation work since ALICE-USA Proposal Three, week-long ALICE-USA Simulation Workshops since April ~ 10 participants each both US and CERN • Large number of simulated events produced within gALICE framework at LBNL - scale similar to entire ALICE mock data challenge at CERN. Basic Issues • Jet trigger performance, bias. • Development and testing of Jet-finding algorithms. • Background event effects. Detector Studies • Simulations directed towards detector optimization • Hadronic section also? No, no big improvement. • Preshower section? No, no big improvement. • Segmentation? Smaller is better -> decrease cell size. Physics Performance Studies • Fragmentation, underlying event, heavy quarks, strangeness, ……

7. TOF TRD HMPID TPC PMD PHOS ITS Muon arm ALICE Detector

8. HMPID TOF TRD TPC 60 < J < 62! PHOS Event Display Pb+Pb

9. New Tracking Performance Fake Tracks! 9% • Reconstruction efficiency • dNch/dy = 8000, B = 0.4T • 98% in TPC • Momentum resolution: • dNch/dy = 8000, B = 0.4T • Combined tracking ITS+TPC+TRD • 9% (pt = 100 GeV/c)

10. NewPID Summary New Relativistic Rise dE/dx Results

11. The basic physics discussed here….. Parton energy loss via induced gluon radiation in the dense medium

12. ALICE: Energy Range (Pb+Pb) Soft->SemiHard->Hard 2 GeV 20 GeV100 GeV, 200 GeV Mini-Jets 100/ev 1/event100k/year Event structure and properties pT>2 GeVEvent-by-event well “Underlying” Event Fluctuationsdistinguishable objects Resolution limit Inclusive (correlation) studies Reconstructed Jets leading particle analysis, particle correlations, ... cone algorithms for jets and multi-jets

13. STAR Au+Au 200 GeV Preliminary pt (GeV/c) Identified mesons versus Baryons Jet Phenomena at low PT at RHIC RCP: Central Au+Au versus Peripheral Au+Au STAR nucl-ex/0305015 Inclusive Hadrons

14. Central Au + Au Peripheral Collisions Recent data from STAR at RHIC: Away-side jet absorbed in Central Collisions? ! No – Probably just below PT threshold used in correlation -> Need Low PT Tracking Central Collisions

15. How will this physics look in ALICE? Inclusive po prediction Vitev and Gyulassy Data: SPS: WA98 RHIC: PHENIX Range of initial state gluon Density dN/dy = 2000 - 3500 Perhaps as little as a few % of hadrons from hard collisions will survive in this PT range

16. away side jet signal STAR TPC data AuAu Simulation of f-correlation due to mini jets in central PbPb ALICE TPC is the perfect tool for this Physics

17. Low PT jets and mini-jets 1/R dN/dR correlation of high PT hadrons 1000 HIJING Events Fragmentation Function of Correlated Particles Background of uncorrelated Particles

18. TPC and inner tracker allow flavor tagging in low PT jets Hadronic Charm reconstruction

19. Can it really be measured At the LHC? Non Flow Unambiguous determination of collision geometry is a “soft tracking problem” What about elliptic flow?

20. At higher PT, Jets are identifiable as distinct objects above the PbPb background at LHC energy. Is there a measurable jet energy loss?

21. Parton Axis R Wiedemann et al. QCD model for induced radiation: A PYTHIA event generator model for parton energy loss R~0.1 Radiating 20 GeV from a 100 GeV parton a la Wiedemann et al -> same Radiation pattern as a 20 GeV PYTHIA Jet except at small angles

22. There may be no significant jet energy loss to be measured….. 100 GeV PYTHIA Compared to Wiedeman et al for 20 GeV parton energy loss In this model: Jet energy loss is apparent only for limited cone radii.

23. Primary jet quenching effect is thus redistribution of energy along and perpendicular to the jet axis. A goal of the ALICE jet physics program is to measure this energy redistribution, it’s dependence on centrality and flavor. A model for the signal at low and high PT 80 + 4*5 GeV/c 80+10+10 GeV/c 80 + 20 GeV/c 100 GeV/c 5 10 15 20 25

24. Sample of Physics Performance Results

25. Trigger with EMCal = electromagnetic energy + ~40 - 50% hadronic energy Trigger bias independent of PT of charged hadrons within ~10% Trigger turn-on versus Ejet

26. Opportunity at the LHC to go beyond inclusive measurements 100 and 200 GeV Jets imbedded in Central PbPb Event But, underlying event dominates jet energy resolution at lower PT

27. 100 GeV/c jets in pp Jet finding and reconstruction: Simple energy flow analysis: Ejet =A*SPTch + B*SEMCal 16%

28. Resolution for 100, 50 and 30 GeV/c jets in pp and PbPb versus R PbPb events include full mini jet background from HIJING

29. The Money Plot …..

30. Fragmentation PL and JT Distributions Input versus reconstructed output 100 GeV/c PL JT PL -> Jet Quenching JT -> Transverse Heating (?) 50 GeV/c 30 GeV/c

31. Flavor dependence of jet quenching – three examples of many Leading particle spectrum for K and L lead jets with PT > 75 GeV/c, baryon versus meson quenching (Topological ID) Baryon/anti-Baryon led jets With PT > 75 GeV/c - distinction of quark / gluon quenching (Topological ID)

32. Flavor dependence of jet quenching Exclusive Heavy Quark Jets Electron tagged b-quark jets Rates allow detailed fragmentation functions

33. Cost and Schedule and the Project Critical Path

34. Revised Funding Profile

35. FY04 Continued R&D Funding FY05 Construction Funding Start

36. Pb/Sci EMCal Dh x Df = 1.4 x 2p/3 (Trigger, h, po, direct and thermal g) RICH TPC TRD TOF PHOS ITS ~ 200 T of detector and utilities – Major Integration Issue

37. Old New ECSS Rails

38. First Two Steps of the Critical Path • Rails – Design completed at ALICE expense • Order must be placed no later than 6/15/03 • ALICE will pay rail procurement at this time in return for corresponding contribution to the ALICE common fund at a later date • ECSS – Must be installed beginning 6/15/05. Working backwards: • -> Must be procured starting 12/1/04 • -> Must be funded starting 10/1/04

39. Summary: • The combined power of the EMCal and the ALICE TPC and • other detectors permit a complete measurement of the redistribution • of jet energy parallel to and perpendicular to the jet axis. • Medium modification of the parton fragmentation process including it’s dependence on energy, baryon-meson content and flavor (s,c,b) will be measured including distinguishing leading mesons and baryons. These measurements will span the range of the lowest PT mini jets to ~150 GeV/c.

40. Summary Continued: • The schedule is approaching meltdown. ALICE will rescue us • from critical failure with respect to rail acquisition next month if • not actively discouraged to do so. • The timeline to progress toward construction funding is very tight

41. Extra Slides

42. The Detector: Pb/Scintillator with mega-tile technology ~ 20k towers in Df x Dh = 2p/3 x 1.4 Towers exactly projective with tiles ~ 5cm x 5cm Resolution (simulated) (sE/E )2= (12.2%/E)2 + (0.4%)2 Photo Detectors: 5mm x 5mm APD’s Modular design permitting “late” installation

43. Technical issues: Optical studies with 5cm x 5cm tiles and WLS readout via 0.5mm fiber Achieve ~1.5 % RMS spatial uniformity

44. Figure 5. Comparison for ideal jet resolution of the quenched and unquenched fragmentation functions of 100 GeV jets in a schematic model in which a 20 GeV primary parton energy loss is modeled as the production of a 20 GeV jet in consort with an 80 GeV jet. The Statistics correspond to only 1000 events. The properly normalized background for central HIJING PbPb events is shown.

46. Computing It is anticipated that at least one Tier-1/2 (regional center for simulations and data analysis with permanent storage) and a number of Tier 3 facilities will be located in the US. The NERSC/PDSF at the LBNL and the OSU at Ohio are possible hosts for Tier1/2. Equipment cost for Tier1/2 (calculated for PDSF) is estimated at $0.5 M in 2006-8, with recommended additions of $0.25 M/year in 2009 and 2010.