john harris (yale) qcd town meeting, rutgers university, 12 – 14 jan 2007 alice-usa lhc alice...

John Harris (Yale) QCD Town Meeting, Rutgers University, 12 – 14 Jan 2007

ALICE-USA

LHC

Alice

Dedicated “general purpose”Heavy Ion experiment at LHC


ALICE Collaboration

~ 1000 Members

(63% - CERN States)

~ 30 Countries

~ 100 Institutes

~ 150 M CHF capital

(+ ‘free’ magnet)

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1990 1992 1994 1996 1998 2000 2002 2004

ALICE Collaboration statistics

LoI

MoU

TP

TRD


ALICE Set-upHMPID

Muon Arm

TRD

PHOS

PMD

ITS

TOF

TPCSize: 16 x 26 meters

Weight: 10,000 tons

EMCal


ALICE Detectors & Acceptance

(charged particles)

µ arm

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 magnet10 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


Heavy Ion Physics at the LHCLHC Heavy Ions –

• guided by pQCD predictions • expectations (detector simulations) based on RHIC extrapolations and theory• lesson from RHIC – guided by theory + versatility + “expect the unexpected”

Soft Physics at LHC – • smooth extrapolation from SPS RHIC LHC?• expansion will be different (v2, HBT, Tchem & Tkin,

strange/charm particles & resonances)

1 event : 5000

C(q

inv)

q inv (GeV/c)


Heavy Ion Physics at the LHCLHC Heavy Ions –

• guided by pQCD predictions • expectations (detector simulations) based on RHIC extrapolations and theory• lesson from RHIC – “expect the unexpected”

Soft Physics at LHC – • smooth extrapolation from SPS RHIC LHC?• expansion will be different (v2, HBT, Tchem & Tkin,

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 pT processes

• abundance of heavy flavors• probe early times, calculable precision studies!

bb (LHC ) ~ 100 bb (RHIC)

cc (LHC) ~ 10 cc (RHIC)


ALICE Physics Measurements

Hard Probes – Jet Quenching• Jets, pi-zeros, leading particles to large pT

Hard Probes – Heavy Quarks• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)

Hard Probes – Quarkonia• J/, , ’ (excellent), ’’(2-3 yrs), ’ (NO WAY…)

Soft Probes – “ala RHIC” • Expansion dynamics different from RHIC due to timescales, densities• All soft physics measurements as at RHIC so far (+ extended PID)• Day 1 physics +


ALICE-USA

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

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


Scientific Focus of ALICE-USA Primary Scientific Goal

“Investigate QCD matter and measure its properties at high at the LHC”

Primary Focus – 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

pT

Investigate energy propagation in medium to determine medium properties


ALICE EMCal

10+1/2+1/2=11 super-modules8 SM from US3 SM from France, Italy

Lead-scintillator sampling calorimeter = 1.4, =110o

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 pT ~ 30 GeV

Approved by LHCC 9/28/06

Allows Jet Measurements with ALICE


Capabilities of ALICE Extended by 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:

104 / year in minbias Pb+Pb:

inclusive jets: ET ~ 200 GeV

dijets: ET ~ 170 GeV

: pT ~ 75 GeV

inclusive : pT ~ 45 GeV

inclusive e: pT ~ 30 GeVThanks – P.Jacobs


ALICE Performance for Jets

ET = 100 GeV, R = 0.4

EM (TPC+EMCal)

(TPC)

(TPC – like RHIC)

size) cone ( )()(R 22


Medium Modification of Fragmentation from Jets

Fragmentation along jet axis: z = phadron / p parton

Introduce = ln(Ejet / phadron) ~ ln (1/z):

jet directionz

N. Borghini, U. Wiedemannhep-ph/0506218

# particles with low z increases

# particles with high z deceases

z/1ln

pThadron~2 GeV

Black line = radiative E-loss

Dashed line = flat = “opaque”

What about collisional E-loss?


ALICE-USA Manpower

ALICE-USA Collaboration Manpower Estimates

from 12 DOE-supported research institutions:

Creighton , Houston, Kent State, LBNL, LLNL, Michigan State, Oak Ridge,

Purdue, Tennessee, Texas, Wayne State, and Yale

FTEs estimate for:EMCal detector support, trigger, computing, simulations & analysis, and papers


Summary and PurposeMuch to understand and significant high pT physics

at upgraded RHIC (& detectors) luminosity at LHC

ALICE - versatile, general purpose heavy ion detector at LHCwill contribute significantly to understanding of HI physics

ALICE-USA and EMCal add significant physics to ALICEmeasure and trigger on jets, photons, pi-zerosheavy quark jet tagstriggered jets response of medium

ALICE-USA seeks community & DOE support to participate in ALICEconstruct EMCalextract exciting, fundamental physics


Back-up Slides


Particle reconstruction and identification capabilities: unique to ALICE Global tracking (ITS-TPC-TRD) + dE/dx (low pT + relativ. rise), TOF, HMPID, PHOS, …

Invariant mass, topological reconstruction Acceptance / efficiency / reconstruction rate () / contamination pT range (PID or stat. limits) for 107 central Pb-Pb and 109 min. bias pp

Identified particle spectra

Pb-Pb

Mid-rapidityPID in the relativistic rise

p

K

Pb-Pb

pT (GeV/c)

For ~ 20 particle species for -1 < y < +1 and -4 < y < +2.5

, K, p: 0.1- 0.15 to 50 GeV Weak or strong decaying particles: to 10-15 GeV

john harris (yale) qcd town meeting, rutgers university, 12 – 14 jan 2007 alice-usa lhc alice...

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