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

ALICE-USA Collaboration Outline Collaboration The ALICE Detector and the Proposed Physics Physics Performance Studies Cost and Schedule and the Critical Path

ALICE-USA Collaboration 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

ALICE-USA Collaboration Ph.D. Manpower Profile Student Profile

ALICE-USA 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 physics from BEVALAC to RHIC – HBT, Strangeness, Collective Flow, Direct and Thermal Photons, E-by-E, High P T, etc. The collaboration expects to participate in all these areas at ALICE but as last time, the presentation focuses on high Q 2 processes as a subset of our entire program The Collaboration……

ALICE-USA Collaboration Simulation work since ALICE-USA Proposal 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, …… Three, week-long ALICE-USA Simulation Workshops since April ~ 10 participants each both US and CERN

ALICE-USA Collaboration TPC PHOS Muon arm TOF TRD HMPID PMD ITS ALICE Detector

ALICE-USA Collaboration Event Display Pb+Pb TRD HMPID TOF TPC PHOS 60  <  < 62 

ALICE-USA Collaboration New Tracking Performance Reconstruction efficiency –dN ch /dy = 8000, B = 0.4T –98% in TPC Momentum resolution: –dN ch /dy = 8000, B = 0.4T –Combined tracking ITS+TPC+TRD –9% (p t = 100 GeV/c)  9% Fake Tracks!

ALICE-USA Collaboration New PID Summary New Relativistic Rise dE/dx Results

ALICE-USA Collaboration The basic physics discussed here….. Parton energy loss via induced gluon radiation in the dense medium

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

ALICE-USA Collaboration R CP : Central Au+Au versus Peripheral Au+Au STAR nucl-ex/ Inclusive Hadrons STAR Au+Au 200 GeV Preliminary p t (GeV/c) Identified mesons versus Baryons Jet Phenomena at low P T at RHIC

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

ALICE-USA Collaboration How will this physics look in ALICE? Vitev and Gyulassy SPS: WA98 RHIC: PHENIX Inclusive  o prediction Data: Range of initial state gluon Density dN/dy = Perhaps as little as a few % of hadrons from hard collisions will survive in this P T range

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

ALICE-USA Collaboration 1/R dN/dR correlation of high P T hadrons Fragmentation Function of Correlated Particles Background of uncorrelated Particles Low P T jets and mini-jets 1000 HIJING Events

ALICE-USA Collaboration TPC and inner tracker allow flavor tagging in low P T jets Hadronic Charm reconstruction

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

ALICE-USA Collaboration At higher P T, Jets are identifiable as distinct objects above the PbPb background at LHC energy. Is there a measurable jet energy loss?

ALICE-USA Collaboration R Parton Axis 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 R~0.1 Wiedemann et al. QCD model for induced radiation: A PYTHIA event generator model for parton energy loss

ALICE-USA Collaboration There may be no significant jet energy loss to be measured… 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.

ALICE-USA Collaboration 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 GeV/c GeV/c A model for the signal at low and high P T GeV/c *5 GeV/c

ALICE-USA Collaboration Sample of Physics Performance Results

ALICE-USA Collaboration Trigger with EMCal = electromagnetic energy + ~ % hadronic energy Trigger turn-on versus E jet Trigger bias independent of P T of charged hadrons within ~10%

ALICE-USA Collaboration 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 P T

ALICE-USA Collaboration 100 GeV/c jets in pp 16% Jet finding and reconstruction: Simple energy flow analysis: E jet =A*  P T ch + B*  EMCal

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

ALICE-USA Collaboration The Money Plot …..

ALICE-USA Collaboration Fragmentation P L and J T Distributions Input versus reconstructed output 100 GeV/c 50 GeV/c 30 GeV/c PLPL JTJT P L -> Jet Quenching J T -> Transverse Heating (?)

ALICE-USA Collaboration Flavor dependence of jet quenching – three examples of many Leading particle spectrum for K and  lead jets with P T > 75 GeV/c, baryon versus meson quenching (Topological ID) Baryon/anti-Baryon led jets With P T > 75 GeV/c - distinction of quark / gluon quenching (Topological ID)

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

ALICE-USA Collaboration Cost and Schedule and the Project Critical Path

ALICE-USA Collaboration Revised Funding Profile

ALICE-USA Collaboration FY05 Construction Funding Start FY04 Continued R&D Funding

ALICE-USA Collaboration Pb/Sci EMCal  x  = 1.4 x 2  /3 (Trigger, ,  o, direct and thermal  TPC TRD TOF PHOS RICH ITS ~ 200 T of detector and utilities – Major Integration Issue

ALICE-USA Collaboration Old New Rails ECSS

ALICE-USA Collaboration First Two Steps of the Critical Path 1.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 2.ECSS – Must be installed beginning 6/15/05. Working backwards: -> Must be procured starting 12/1/04 -> Must be funded starting 10/1/04

ALICE-USA Collaboration 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 P T mini jets to ~150 GeV/c.

ALICE-USA Collaboration 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 Summary Continued:

ALICE-USA Collaboration Extra Slides

ALICE-USA Collaboration The Detector: Pb/Scintillator with mega-tile technology ~ 20k towers in  x  = 2  /3 x 1.4 Towers exactly projective with tiles ~ 5cm x 5cm Resolution (simulated)  E /E ) 2 = (12.2%/  E) 2 + (0.4%) 2 Photo Detectors: 5mm x 5mm APD’s Modular design permitting “late” installation

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

ALICE-USA Collaboration 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.

ALICE-USA Collaboration

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 , with recommended additions of $0.25 M/year in 2009 and Computing