DOE Briefing - 9/13/05 M.D. Baker 1 LHC Heavy Ions with ATLAS Mark D. Baker Brookhaven National Laboratory

DOE Briefing - 9/13/05 M.D. Baker 1

LHC Heavy Ions with LHC Heavy Ions with ATLAS ATLAS Mark D. Baker

Brookhaven National Laboratory


OutlineOutline

• This talk - US-ATLAS-HI• The Scientific Opportunity• Cost-effectiveness: Synergistic Approach• The Plan(s) & cost estimates

• Plan “A” - Fleshing out the proposal to NSAC• Plan “B” - Reasonable fallback option

• Sam Aronson - the big picture• Balance/Priority between US-ATLAS-HI & RHIC


Suppression persists all the way till 20 GeV/c

• Suppression is strong (RAA =0.2!) and flat up to 20 GeV/c

• Matter is extremely opaque

• The data should provide a lower bound on the initial gluon density

I. Tserruya, QM05 Summary


Limitations of RLimitations of RAAAA

K.J. Eskola et al., NP A747, 511

Central RAA Data

?R

AA a

t 10

GeV

/c

• Leading hadrons preferentially arise from the surface• Limited sensitivity to the region of highest energy density• Need more penetrating probes

q̂ (proportional to gluon density)

C. Gagliardi

STARSTAR


Limitations of RLimitations of RAAAA

• Dainese, Loizides, Paic describe surface bias• X.N. Wang et al. Claim dE/dx ~ 14±4 GeV/fm• Need more penetrating probes

A. Dainese, C. Loizides, G. Paic, Eur. Phys. J. C38(2005) 461

K.J. Eskola et al., NP A747, 511

Central RAA DataRA

A a

t 10

GeV

/c

q̂ (proportional to gluon density)

@ RHIC!


Di-jets at much higher pDi-jets at much higher pTT

8 < pT(trig) < 15 GeV/c

STAR Preliminary

pT(assoc)>6 GeV

Clear emergence of the away-side jet

No background subtraction!

C. GagliardiD. Magestro, sect 3b


Observation 1 on away-side peaks: Observation 1 on away-side peaks: Widths Widths

Away-side widths similar for central, peripheral

8 < pT(trig) < 15 GeV/c

pT(assoc)>6 GeV

STARSTAR J. Dunlop

D. Magestro, sect 3b


The matter is so dense that The matter is so dense that even heavy quarks are even heavy quarks are

stoppedstoppedEven heavy quark (charm) suffers substantial energy loss in the matter

The data provides a strong constraint on the energy loss models.

The data suggest large c-quark-medium cross section; evidence for strongly coupled QGP?

(3) q_hat = 14 GeV2/fm



(4) dNg / dy = 1000

Electrons from c & b

Y. Akiba


The matter is so strongly The matter is so strongly coupled that even heavy coupled that even heavy

quarks flowquarks flow• Charm flows, but not as

strong as light mesons.

• Drop of the flow strength at high pT. Is this due to

b-quark contribution?• The data favors the

model that charm quark itself flows at low pT.

• Charm flow supports high parton density and strong coupling in the matter. It is not a weakly coupled gas.

Greco,Ko,Rapp: PLB595(2004)202

Y. Akiba


The matter is so dense that it The matter is so dense that it modifies the shape of jetsmodifies the shape of jets

• The shapes of jets are modified by the matter.• Mach cone?• Cerenkov?

• Can the properties of the matter be measured from the shape?• Sound velocity• Di-electric constant

• Di-jet tomography is a powerful tool to probe the matterPHENIX preliminary

Y. Akiba


The perfect ink…The perfect ink…

• Is brilliantly dark and opaque• Yet flows smoothly and easily

B. Müller E. Shuryak

• Supersonic jets in medium??

ATLAS will allow us to study the shape of the jet event-by-event“Chromo-sonic” boom in an ATLAS lego plot?


Anyway, MANY more Anyway, MANY more details...details...

High-pT Photon and Hadron Probesof Dense Matter Created in Heavy

Ion Collisions @ RHIC

Prof. Brian A. Cole.Columbia University

See e.g.:


My summary of QM2005My summary of QM2005• The matter produced at RHIC is VERY black

• 20 GeV hadrons or 30 GeV jets are NOT “penetrating probes”!• Extensive, detailed studies are needed to disentangle RHIC physics:

• One-jet vs. two-jet events

• RAA vs.

• Multiparticle correlations to access Mach or Cerenkov cones

• Really high pT jets at the LHC should clarify RHIC physics

• RAA of single particles along with reconstructed jets, dijets, +jet events

• The ATLAS detector is DESIGNED to study jets

• Heavy quarks are flowing• Study them carefully at RHIC with PHENIX & STAR upgrades

• higher pT, better background rejection, charm/beauty separation

• Study them at the LHC where they are copiously produced

• Multiplicity, radial & elliptic flow also very interesting...


Why LHC?Why LHC?

Takai, November 2004


Why ATLAS (&LHC)?Why ATLAS (&LHC)?


ATLAS is the best jet ATLAS is the best jet detector EVER!detector EVER!

• Calorimeter designed for jets (#1 in the world)• Truly hermetic over -4.9 < < +4.9 due to

integrated design of barrel & endcap & forward cal. • EMCAL is much more finely segmented in R,

• Caveat: CMS E resolution is better at low occupancy

• Hadron CAL is deeper & more finely segmented• Better Jet E/E (ideal case: 50%/E (GeV)

• FCAL is segmented in R, • Especially important for forward physics & pA


ATLAS as a Heavy Ion ATLAS as a Heavy Ion DetectorDetector

— Hermetic coverage up to || < 4.9— Fine granularity (with longitudinal segmentation)— Very good jet resolution

— Coverage up to || < 2.7

— Large coverage up to || < 2.5— High granularity pixel and strip detectors— Good momentum resolution

High pT probes (jets, jet shapes, jet correlations, 0)

Muons from , J/, Z0 decays

Tracking particles with pT 0.5 GeV/c

2.+ 3. Heavy quarks(b), quarkonium suppression(J/ ,)

1.& 3. Global event characterization (dNch/dη, dET/dη, flow); Jet quenching

1. Excellent Calorimetry

3. Inner Detector (Si Pixels and SCT)

2. Large Acceptance Muon Spectrometer


Jet Reconstruction- Sliding window algorithm, = 0.4 0.4, after subtracting the pedestal (the average pedestal is 50 11 GeV)

- Accepted, if ET(window) > 40 GeVThe used algorithm is not optimal, studies are ongoing.

Di-jet event from PYTHIA in pp: pT

hard=55GeV

Di-jet embedded in PbPb before pedestalsubtraction

Di-jet embedded in PbPb after pedestalsubtraction

Di-jet reconstructed in PbPb


• For ET > 75GeV: efficiency > 95%, fake < 5%• Good energy and angular resolution • Next: use tracking information to lower the threshold and reduce the fakes

Jet reconstruction Jet reconstruction efficiencyefficiency

Angular resolution

for 70 GeV jets

~2 resolution in pp

Pb-Pb collisions (b= 0 –1 fm)

EfficiencyFake rate

Energy resolutionPb-Pb

p-p


Jet Studies with Tracks- Jets with ET = 100 GeV- Cone radius of 0.4- Track pT > 3 GeV

Fragmentation functionMomentum componentperpendicular to jet axisjet

TtrackT E/pz

PbPb HIJING-unquenched ppdN/djT broader in PbPb than in pp

(background fluctuations)Promising, but a lot of additional work is needed!


Heavy Quark Tagging

Rejection factor against u-jets ~ 100for b-tagging efficiency of 25%

Should be improved by optimized algorithms

and with soft muon tagging in the Muon Spec.

b-tagging capabilities offer additional tool to understand quenching.

To evaluate b-tagging performance:- ppWHlbb events overlayed

on HIJING background have been used.- A displaced vertex in the Inner Detector

has been searched for.


Focus for US-ATLAS-HIFocus for US-ATLAS-HI• Day 1 physics

• Improve/adapt algorithms for basic triggering• Improve/adapt global event algorithms

• High pT, jet & heavy flavor physics• Improve/adapt jet & flavor-tagging algorithms

• BNL as center of US-ATLAS-HI • Computing • Theory• Analysis

• ZDC for ATLAS


Basic ToDo listBasic ToDo list• Analysis Software:

• Standard Atlas codes work “out of the box”• Improvements needed because PbPb background

is different from pp:• PbPb: Underlying soft event with radial & elliptic flow• Pp: Pileup from previous events

• Ideas from RHIC also needed

• Triggering• Participate in “day 1” minbias p+p.• Again primarily tweaks to existing software

(hardware OK)


US ATLAS Tier 1 Center (HEP) At BNL

FY05 FY08FY05 FY08

CPU FarmCPU Farm 0.5 MSI2k0.5 MSI2k 7.9 MSI2k7.9 MSI2k

DISKDISK 0.2 PB0.2 PB 4.6 PB4.6 PB

FTEsFTEs 12.512.5 2020

NetworkNetwork 2.5 GB/s2.5 GB/s 20 GB/s20 GB/s


Zero-Degree CalorimetryZero-Degree Calorimetry• Useful for Heavy Ion Physics

• centrality• luminosity measurement

• Useful to mainstream Atlas Collaboration / LHC• Day 1 p+p collision tuning & luminometry

• A. Ratti, H. Schmickler, S. White

• eRHIC preview (low Q2)• Ultraperipheral collisions yield

• high energy & A


Luminosity Scale in Heavy Luminosity Scale in Heavy Ion Runs from Calculated Ion Runs from Calculated

EM ProcessesEM Processes ATLAS Zero Degree Calorimeter Stationed @ +/-140m from I.P. EM processes in RHIC data

for PbPb@LHC A.J.Baltz, C.Chasman and S.White NIM A417 (1998) 1


After 1 nominal month of PbPb:“~10 times the x reach of HERA for fixed virtuality”

Strikman, Vogt, White, hep-ph/0508296

20 GeV 5.5 A TeV Pb

Jets into the large acceptance calorimeter!

Probing small x parton Probing small x parton densitiesdensities

Ultraperipheral AA collisions

Preview of eRHIC


Synergy with RHIC/BNL:Synergy with RHIC/BNL:• Idea center

• Almost all HI experimentalists and many theorists visit every year.

• Won’t ever be true at FNAL and unlikely at CERN

• Active ongoing experiments• Will the best ideas come from Monte Carlo studies?

• World-leading and still growing experience in• High pT physics analyses (PHENIX)

• Multi-level triggering (PHENIX)• Zero-degree calorimetry (S. White)

• Strong U.S. universities active on ATLAS & RHIC• Colorado, Columbia, Iowa State, Stony Brook


Synergy with Synergy with US-ATLAS/ACF:US-ATLAS/ACF:

• USATLAS Tier 1 Computing Facility • Overlap with the RCF

• Known and smooth working relationships

• Natural & expected place to put ATLAS-HI Tier 1/2• Tier 1: Contains/analyzes the “data summary tapes”• Tier 2: Simulations run in “Tier 2”

• DOE-HE-funded Atlas (+ACF) people• 25-30 FTEs now, should grow to ~45 FTEs

• 12 FTE physicists playing a central USATLAS analysis role

• Int’l connections: Heavy Ion & Forward Phys.• ATLAS-HI co-convened by Helio Takai. • Cracow group has a close connection to BNL-Chem.• IHEP-Protvino, & LBNL(HE) to White.


Plan APlan A

As presented previously


““NSAC” Operations NSAC” Operations ChartChart

$1.5M & $2.3M are small!Must compare apples to apples!

E.g. FY05 PHOBOS total U.S. Effort ~$4M

??

??

Total U.S. Effort


Costing assumptionsCosting assumptions• Labor

• Must count ALL people - research & detector operations.

• Fully burdened: Salaries + Fringe + Overhead

• MST• $15k/head fully burdened• Or $20k/full-time & $10k/part-time

• Computing• Assumes Tier 1/2 US-ATLAS-HI center at BNL

• M&O• as projected - per head


Bottom-up costingBottom-up costingUniversity Lab

(BNL/LANL/LBL)

Prof.(summer) ~$30k N/A

Staff member ~$180k ~$250k

Postdoc(off/on-campus)

$75-90k ~$90k

Student $30-60k ~$35k


University groupsUniversity groups• Small group at a low-tuition university

• 1 professor + 1 postdoc + 1 student• $135,000 in burdened labor

• Large group at a high-tuition university• Professors on hard money• 3 staff + 2 postdocs + 5 students• $1,000,000 in (burdened) labor


Labor Steady State Model Labor Steady State Model (FY09+)(FY09+)

• BNL• 2 FTEs (4 heads), staff• 3 FTEs (4 heads), postdocs• 2 Students (SUNYSB)

• University Groups• 5 summers (10 heads) of

Professors (=“5 FTEs”)• no staff• 5 postdocs• 10 students• Expected groups:

• Colorado

• Columbia

• Iowa State

• SUNYSB-Chem

• SUNSB-Phys ??

$1790k = $840k + $950k

27 FTEs = 7 + 2035 heads = 10 + 25


““NSAC” Operations NSAC” Operations ChartChart

Should be the smallest of the three requestsin FY09 if the methodology is consistent!

Total U.S. EffortSteady State

FY09

1790620350135

2895

3527


ZDC budget requestZDC budget request


Plan BPlan B

• Ramp people more slowly • Part-time RHIC, part-time HIJING

• Buy computers a bit later

• Minor ZDC redesign & stretch-out• & Collaborate with LBNL-HE & LARP


BNL NP manpower proposal BNL NP manpower proposal (FY05$) (FY05$)

• FY05: 0.75 FTEs ($200k), 3 heads• FY06: 1.5 FTEs ($295k), 4 heads

• FTEs: 1 staff, 0.5 postdoc• Heads: Baker, Steinberg, White, new postdoc

• FY07: 3.5 FTEs ($500k), 7 heads• FTEs: 1.5 staff, 1 postdoc, 1 student• Heads: 4 staff, 2 postdocs, 1 student

• FY08: 6 FTEs ($750k), 9 heads• FTEs: 2 staff, 2 postdocs, 2 students• Heads: 4 staff, 3 postdocs, 2 students

• FY09: 7 FTEs ($840k), 10 heads (STEADY STATE)

• FTEs: 2 staff, 3 postdocs, 2 students• Heads: 4 staff, 4 postdocs, 2 students


Univ. NP manpower model Univ. NP manpower model (FY05$) (FY05$)

• FY05: 0.25 FTEs (), 2 heads• FY06: 3 FTEs ($150k), 4 heads

• FTEs: 1/1/1 (prof./ postdoc / student)• Heads: 2/2/1

• FY07: 7 FTEs ($380k), 10 heads• FTEs: 2/2/3• Heads: 4/3/3

• FY08: 12 FTEs ($570k), 15 heads• FTEs: 3/3/6• Heads: 6/3/6

• FY09: 20 FTEs ($950k), 25 heads (STEADY STATE)

• FTEs: 5/5/10 (prof./ postdoc / student)• Heads: 10/5/10


Old Operations chartOld Operations chart

200

15

00

30

230

Total U.S. Effort


Plan BPlan B

445200 880 1320

New plan in Blue

15

4.59

10.517

1824

0 500 25

30 135 2755060

42032590

230 655 1265 2155

FY09

1790620350135

2895

3527

Total U.S. Effort

Steady State


FY06 @ BNL: non-NP vs. NPFY06 @ BNL: non-NP vs. NP• Non-NP money @ BNL

• High Energy: Helio Takai, Pavel Nevski• LDRD postdoc: Arthur Moraes• Fulbright fellow: Mate Csanad• ~2 FTEs in FY06

• NP money @BNL (proposed)• 40% Baker, 40% Steinberg, 25% White• + new postdoc 50%/50% Atlas/Phenix

• replaces Zhengwei Chai (RA) from Phobos

• ~1.5 FTEs


Scale of BNL EffortScale of BNL Effort• Compare to FY05 “PHOBOS” group

• Operations effort: ~$1.85M• Computing capital (in RCF): ~$300k

• FY09 BNL (NP) ATLAS effort is:• Smaller in terms of operations

• At BNL• In the U.S. overall

• Comparable in terms of computing capital needs


U.S. Atlas Heavy I on Physics - Operations

FY06 FY07 FY08 FY09Costs US BNL BNL US BNL BNL US BNL BNL US BNL BNL

total total new total total new total total total total total newLabor 445 295 0 880 500 80 1320 750 205 1790 840 295MST 135 55 0 275 105 35 420 150 75 620 170 95Computing 50 50 0 50 50 0 325 325 325 350 350 350M&O Cat.A 25 10 0 60 25 5 90 35 15 135 40 20Total 655 410 0 1265 680 120 2155 1260 620 2895 1400 760

StaffingU.S. Authors 9 4 0 17 7 2 24 9 4 35 10 5FTE's 4.5 1.5 0 10.5 3.5 1.5 18 6 3.5 27 7 4.5

Constant FY 05 $k

Breakdown of BNL & U.S.Breakdown of BNL & U.S.


ZDCZDC

FY 05 FY 06 FY 07 TotalPre-R&D 0R&D 5 5CDR 0PED/EDIA 25 27 52Construction 80 140 220Preops 0

TEC 0 105 167 272TPC 5 105 167 277

Planned RedirectNeeded New Funds (TPC-redirect) 5 105 167 277

ZDC Calorimeter Construction

Constant FY 05 $k

TPC lowered from $500k.Proposal: Use BNL-NP baseline capital

75 350 75 500Old numbers:


Summary of “Project” PlanSummary of “Project” Plan• No actual DOE MIE project requested.

• Research Operations funding requested• Recurring capital computing expense requested• ZDC proposed as a small capital project funded

through BNL-NP baseline capital


CERN view of ATLAS-HICERN view of ATLAS-HI• LHCC (LHC Committee):

• “encourages the ATLAS Collaboration to continue their studies for heavy ion physics with a view to submitting a Physics Performance Report.” - May 2004

• Hermann Schmickler, CERN-AB-BDI-GL• w/ S. White: “On the Potential Use of Zero-Degree

Calorimetry for LHC Luminosity Monitoring”, LARP Meeting, Port Jefferson, NY - April 2005

• Glossary:• AB = Accelerators and Beams Dept. • BDI= Beam Diagnostics & Instrumentation• GL = Group Leader• LARP = U.S. LHC Accelerator Research Program


ATLAS HI SummaryATLAS HI Summary• ATLAS is ideal for studying jets & quarkonia

• high granularity of the calorimeter• external muon spectrometer• Si vertex detector availability on day 1

• Very leveraged investment• Collaboration requirements on DOE-NP are minimal

• manpower for triggering & physics analysis• some computing resources• ZDC would be a valuable contribution

• Strong U.S.ATLAS (HEP) group in proximity to RHIC

• U.S. ATLAS-HI Collaboration is healthy and growing• Lots of work & great physics ahead!


Backup SlidesBackup Slides


Silicon in good shapeSilicon in good shape

Heinz Pernegger


Atlas Heavy Ions (11/2004)Atlas Heavy Ions (11/2004)• European

• LHEP• U. Bern • CERN• Lebedev Institute• INFN• IPNP - Prague• UF -Rio de Janeiro• U. Geneva• INP - Cracow (PHOBOS)

• United States• BNL Physics (NP+HEP)• Colorado• Columbia• (LBNL)

Strong U.S. group already!Strong U.S. group already!NP: Cole, Nagle, White

Assemegan, Gordon, Nevski, Takai




• United States• BNL Physics (NP+HEP)• Colorado• Columbia• (LBNL)• BNL Chemistry• SBU Chemistry

• Interested:• SBU Physics




• United States• BNL Physics (NP+HEP)• Colorado• Columbia• (LBNL)• BNL Chemistry• SBU Chemistry• Iowa State

• Interested:• SBU Physics

Documents

DOE Briefing - 9/13/05 M.D. Baker 1 LHC Heavy Ions with ATLAS Mark D. Baker Brookhaven National Laboratory