ATLAS first run scenarios Paula Eerola, Lund University 13th Nordic LHC Physics Workshop Helsinki...

ATLAS first run scenariosATLAS first run scenarios

Paula Eerola, Lund UniversityPaula Eerola, Lund University13th Nordic LHC Physics Workshop13th Nordic LHC Physics Workshop

Helsinki 26-27 October 2006Helsinki 26-27 October 2006

Paula Eerola13th Nordic LHC Physics Workshop

Helsinki 26-27 October 20062

This talk includes:This talk includes:

• ATLAS status– From H. Burckhart, ”ATLAS Detector and Commissioning

Status”, Beauty 2006, Sep 2006

• A summary of the LHC start-up scenario

• The LHC commissioning run (450 GeV + 450 GeV) until the end of 2007

• The first physics run at 14 TeV



ATLAS LayoutATLAS Layout

• Tracking (||<2.5, B=2T) : -- Si pixels and strips (SCT) -- Transition Radiation Detector (TRT): e/ separation

• Calorimetry (||<5) : -- EM : Pb-LAr -- HAD: Fe/scintillator (central), Cu/W-LAr (fwd)

• Muon Spectrometer (||<2.7) : air-core toroids with muon chambers (MDT, CSC)



All modules have been delivered with good yield.

End-Caps: Both EC have been integrated, delivered at CERN and acceptance tested. Cosmics tests starting in October.

Barrel: Stave production is completely finished. Layer2 has been integrated, Layer1 integration is proceeding. The best staves (least dead channels, best thermal performance) are reserved for the b-layer, integration planned for November.

Pixel ready for installation April 2007. Pixel ECC, 3 disks visible

Pixel Layer2 clampedPixel Layer2 – Half shell

Pixel statusPixel status



SCT statusSCT status

(Picture taken by a star-photographer, P. Ginter, as art-work…) (Picture taken at Oxford)

Completed SCT End-Cap disk SCT Barrel 6

Barrel SCT (+ TRT) installedBoth End-Caps ready for insertion in TRT:EC C this week, EC A in NovemberReady for installation January 2007



SCT Barrel IntegrationSCT Barrel Integration

Barrel 6 insertion into thermal shield



Cosmics in the barrel TRTBarrel TRT during insertion of thelast modules (February 2005)Now installed in cavern

TRT BarrelTRT Barrel



TRT End-CapsTRT End-Caps

Both TRT End-Caps are ready for integration with the SCT

A and B type TRT end-cap wheels fully assembled

Barrel: 52k straw tubes 4 mm diameter 150 cm long 36 layers, r = 56-107cm

End cap: 320k straw tubes

Straw resolution 170 μm

Total volume: 16 m3



SCT in TRT Barrel InsertionSCT in TRT Barrel Insertion

Barrel SCT

Barrel TRT

End of February 2006 the barrel SCT was inserted into the barrel TRT



Cosmic track in SCT/TRT BarrelCosmic track in SCT/TRT Barrel

Dead channels:SCT < 0.2%TRT < 1.5%



Transport of SCT/TRT Barrel on 30.August 2006



SCT/TRT barrel in its final SCT/TRT barrel in its final location inside calorimeterlocation inside calorimeter



Calorimeter LayoutCalorimeter Layout

Tile barrel Tile extended barrel

LAr forward calorimeter (FCAL)

LAr hadronic end-cap (HEC)

LAr EM end-cap (EMEC)

LAr EM barrel



27 Oct. 2004: Lowering LAr cryostat

Mounting Tilecal modules 1 Dec 2004: 58 Tile modules mounted

LAr positioning



The barrel LAr and scintillator tile calorimeters in the cavern in their ‘garage position’ January 2005

A cosmic ray muon registered in the barrel Tile Calorimeter

Barrel LAr and Tile Calorimeters



Barrel Toroid coil transport and lowering into the underground cavern

Barrel Toroid installationBarrel Toroid installation



The last coil was moved into position on 25th August 2005

The first coil was installed in October 2004

BT cooling curve

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7/2/0612:00 AM

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8/1/0612:00 AM

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8/31/0612:00 AM

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Tem

per

atur

e [K

]

Cool Down: started 4 July Cool Down: started 4 July 2006200631 August 2006: 4 K31 August 2006: 4 KTest with full current in Test with full current in OctoberOctober


Helsinki 26-27 October 200618 (ATLAS Christmas card 2005)



All components are fabricated, and the assembly is ongoing at CERN

The first of the two ECT cold masses inserted into the large vacuum vessel

End-Cap ToroidEnd-Cap Toroid



Precision chambers:- MDTs in the barrel and end-caps- CSCs at large rapidity for the innermost end-cap stationsTrigger chambers:- RPCs in the barrel- TGCs in the end-caps

The Muon Spectrometer is instrumented with precision chambers and fast trigger chambers

At the end of February 2006 series chamber production in the many sites was completed.

Muon Spectrometer Muon Spectrometer InstrumentationInstrumentation



Installation of barrel muon station (65% done)

A crucial component to reach the required accuracy is the sophisticated alignment measurement and monitoring system

Barrel MDTsBarrel MDTs



First cosmics registered in situ for barrel chambers

In December 2005 in MDTs and in June 2006 in RPCs



First TGC Wheel fully installed



Installation summaryInstallation summary

• ATLAS installation and commissioning proceeds well– Inner Detector

• SCT/TRT Barrel already installed• SCT/TRT End-Caps ready for installation early 2007• We expect to have a complete 3-hit Pixel system installed

at start-up

– All Calorimeter components already installed, now being commissioned with cosmics

– Installation of Muon system ongoing



CommissioningCommissioning

• Stand-alone operation of a subdetector• Integration of each subdetector in central systems

(Trigger, DAQ, DCS, DB, Monitoring, Offline)• Integrated Cosmics data taking• Data taking with beam

– Single beam– Collisions at 2 x 450 GeV



The commissioning runThe commissioning run

• Beam pipe closure end Beam pipe closure end of August 2007of August 2007• LHC commissioning runLHC commissioning run with collisions with collisions at the at the injection energy (√s =900 injection energy (√s =900 GeV), scheduled GeV), scheduled November 2007November 2007• Luminosity typically Luminosity typically L = 10L = 102929cmcm-2-2ss-1-1

• The LHC will be a static The LHC will be a static machine, no ramp, no machine, no ramp, no squeeze, to debug the squeeze, to debug the machine, the detectors machine, the detectors and the data processingand the data processing• A few weeks of stable A few weeks of stable running conditions at the running conditions at the injection energyinjection energy



Triggers for the commissioning Triggers for the commissioning runningrunning

• √√s = 0.9 TeV, L = 10s = 0.9 TeV, L = 102929cmcm-2-2ss-1-1, , inelinel=40 mb <=> 4 kHz =40 mb <=> 4 kHz interaction rateinteraction rate

• Commissioning the detector, the trigger, the offline Commissioning the detector, the trigger, the offline reconstruction and analysis chainsreconstruction and analysis chains

• Data taking with loose level-1 (LVL1) single muon triggers Data taking with loose level-1 (LVL1) single muon triggers (p(pTT>5 GeV) or minimum bias triggers>5 GeV) or minimum bias triggers

• The High Level Trigger (HLT) in pass-through mode for The High Level Trigger (HLT) in pass-through mode for testingtesting

• Minimum bias trigger techniquesMinimum bias trigger techniques– Bunch-crossing LVL1 trigger + selection at LVL2 and/or EF

• Detectors– Minimum-Bias Trigger Scintillators (MBTS) using precision readout– Inner detector (pixels sensitive to low pT)– LUCID and other forward detectors?– Calorimeters?

– MBTS trigger at LVL1 (followed by further selection in HLT)• Some bias at LVL1 ( range; efficiency for minimum-ionizing particles;

multiplicity requirements; etc.)• Needed at very low luminosity where interactions per BC << 1



30% data taking efficiency included.Efficiency of trigger and analysis cuts included.

Event statistics for the commissioning run

W e Z ee

bb 53Xpp + bb J/(53)X

√√ss =900 GeV, L=1029cm-2s-1



Event statistics with B and Quarkonium muonic decays

bb 5 X

bb 53 X

pp J/ (53) X

pp (53) X

√√ss =900 GeV, L=1029cm-2s-1

h 5 X

bb J/ (53)X

Number of days of data taking

Nu

mb

er

of

even

ts in

ATLA

S a

fter

all

cu

ts

30% machine and data taking efficiency assumed. Reconstruction and trigger efficiencies included.



The first physics runThe first physics run

• √√s = 14 TeV, L = 10s = 14 TeV, L = 1032-3332-33cmcm-2-2ss-1-1

The aim is to integrate several fbThe aim is to integrate several fb-1-1 by the end of 2008. by the end of 2008. • Many customers for the dataMany customers for the data

– Data for commissioning the detector, the trigger, the Data for commissioning the detector, the trigger, the offline reconstruction and analysis chainsoffline reconstruction and analysis chains

– Data samples high-pData samples high-pTT physics studies physics studies• Sharing of “bandwidth” between different triggersSharing of “bandwidth” between different triggers• Plus control samples to understand the Plus control samples to understand the

backgrounds, measure the selection efficiency, etcbackgrounds, measure the selection efficiency, etc– Data samples for B-physics studiesData samples for B-physics studies

• Scope depends on luminosity and available HLT Scope depends on luminosity and available HLT resourcesresources

– Data samples for “minimum-bias” physics studiesData samples for “minimum-bias” physics studies• Needed also for tuning Monte Carlo generators used Needed also for tuning Monte Carlo generators used

in other physics studiesin other physics studies



Minimum bias on Minimum bias on day zero?day zero?

Why measure min bias? Why measure min bias? Not exactly what the LHC was built for!Not exactly what the LHC was built for!But…..But….. • Physics: measure dN/d|=0

– Compare to NSD data from SppS and Tevatron

• MB samples for pile-up studies– Calorimeter– Physics analyses

• Overlap with underlying events– analyses eg VBF, Jets…

• Demonstrate that ATLAS is operational• Inter-calibration of detector elements

– Uniform events• Alignment • Baseline for heavy ions

C. Buttar, ATLAS Physics Week May 2006



Event characteristicsEvent characteristics• Event characteristics

– Non-single diffractive~non-diffractive inelastic

– Soft tracks pTpeak~250MeV

– Approx flat distribution in to ||~3 and in – Nch~30; ||<2.5

• Trigger rates ~70mb (NSD!)– R~700kHz @ L=1031cm-2s-1

• Rapidity coverage– Tracking covers ||<2.5

• pT problem– Need to extrapolate by ~x2 Need to understand low pt charge track

reconstruction

M. Leyton

1000 events1000 events

dNdNchch/d/ddNdNchch/dp/dpTT

Black = Generated (Pythia6.2)Black = Generated (Pythia6.2)

Blue = TrkTrack: iPatRecBlue = TrkTrack: iPatRec

Red = TrkTrack: xKalmanRed = TrkTrack: xKalman

Reconstruct tracks with:Reconstruct tracks with: 1) pT>500MeV1) pT>500MeV 2) |d2) |d00| < 1mm| < 1mm 3) # B-layer hits >= 13) # B-layer hits >= 1 4) # precision hits >= 84) # precision hits >= 8

pT (MeV)C. Buttar



Low pLow pTT Min Bias Track Recon Min Bias Track Recon

• Tracker is in principle sensitive to soft tracks– Pt = 400 MeV - tracks reach end of TRT– Pt = 150 MeV - tracks reach last SCT layer– Pt = 50 MeV - tracks reach all Pixel layers

• Strategy 1: Primary track reconstruction• Strategy 2: Secondary track reconstruction• New Strategy: Soft particle reconstruction after

primary vertexing

150MeV

50MeV

400MeV

A.Salzburger

Elsing



Tracking: Startup-Initial AlignmentTracking: Startup-Initial Alignment

• Very first alignment will be based on:– Mechanical precision– Detailed survey data– Cosmics data (SR1/Pit)– Minimum bias events and inclusive bb

• Studies indicate goodefficiencies after initial alignment

– Example taken from T.Golling– Precision will need Zs and

resonances to fix energy scales,constrain twists, etc…

M.Elsing



B cross-section at LHCB cross-section at LHC

• All LHC experiments plan to All LHC experiments plan to measure B-cross section in measure B-cross section in proton-proton collisions. proton-proton collisions.

• Measurements will cover Measurements will cover different phase space – will be different phase space – will be complementary.complementary.

• Partial phase-space overlaps: Partial phase-space overlaps: LHCb, ATLAS, CMS, ALICE - LHCb, ATLAS, CMS, ALICE - opportunity for cross-checks.opportunity for cross-checks.

• Methods of measurement for Methods of measurement for low- and medium-plow- and medium-pTT events in events in ATLASATLAS • bb 6 X ;• bb → 63 X; • Exclusive channels B+→J/

K+, B0→ J/ K0*

• b-b correlations: B→J/ X + b =J/ -



Statistics for bb-events

Decay Statistics with 10 pb-1

Statistics with 100 pb-1

bb 6X 40 M 400 M

cc 6X 20 M 200 M

bb X 2 M 20 M

B J/ X and b X

2 500 25 000

B+→J/K+ 1 700 17 000

B0→ J/K0* 870 8 700



B, J/B, J/ and and measurements measurements

Decay Statistics with 100 pb-

1

Measurement

pp → J/63 1000 k R(bb → J/)/R(pp → J/R(pp → /R(pp → J/bb J/63X 400 k

63 100 k

Decay Statistics or limit with100 pb-1

Measurement today

B+→K+ 23 Belle today 80? B0→ K0* 12

Bs→ 9

b→ 3

Bs→ 6.4×10-8 at 90% C.L.

CDF currently 8.0x10-8 at 90% C.L.



Hadronic top with 100 pbHadronic top with 100 pb-1-1Hadronic top with 100 pbHadronic top with 100 pb-1-1

TP

91% etmiss>20GeV

34% electron-events have exactly 1 electron pt>25GeV

L1 trigger “EM25I “

3 jets with highest are used to form top

9.6% has exactly 4 jets (Cone0.4) pt>40GeV

The fourth jet

Zhu



Top massesTop massesNo trigger+pT(elec)>25 GeV

Trigger=EM25I or MU20

Reconstructed top mass distributions not affected by trigger

Leptonic topHadronic top(no W in-situ calibration)

Pralavorio



ConclusionsConclusions

Commissioning run at 900 GeV, very low luminosity Commissioning of the detector, the trigger, the offline

reconstruction and the analysis chains. In 30 days ~4.7k single muons and ~370 di-muons from

b and c: first tests of trigger and offline muon reconstruction.

90 J/ and 130 : first tests of mass reconstruction.First physics run at 14 TeV, 100 pb-1 – 1 fb-1

Understanding the detector – alignment, material, magnetic field, event reconstruction etc.

Standard Model Physics: Minimum-bias physics and cross-section

measurements at new energy for QCD tests and optimization of trigger strategies.

B, J/ and measurements. Top-physics.

Beyond Standard Model: e.g. inclusive SUSY searches!



Thank you!Thank you!



BACKUP SLIDESBACKUP SLIDES



The figure shows sources of low-pT muons at 14 TeV.

Muons from hadron decays in flight (“h” in the figure) have a softer spectrum than muons from b.

Sources of low-pT single and double muons

LVL1 muon trigger rates @ 14 TeV and 1033cm-2s-1

b

single-muon

di-muon

all

all

h

h

b

b

c

c

J/



Detector configuration during the Detector configuration during the first physics runfirst physics run

• B-layer OK.• ID complete, only TRT C-wheels staged• HLT configuration: full 45kHz LVL1 capacity.

ATLAS first run scenarios Paula Eerola, Lund University 13th Nordic LHC Physics Workshop Helsinki...

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