ATLAS first run scenarios

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ATLAS first run scenarios
Paula Eerola, Lund University 13th Nordic LHC
Physics Workshop Helsinki 26-27 October 2006
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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

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ATLAS Layout

• Tracking (?lt2.5, B2T)
• -- Si pixels and strips (SCT)
• -- Transition Radiation Detector (TRT) e/?
  separation
• Calorimetry (?lt5)
• -- EM Pb-LAr
• -- HAD Fe/scintillator (central), Cu/W-LAr
  (fwd)
• Muon Spectrometer (?lt2.7)
• air-core toroids with muon chambers (MDT, CSC)

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Pixel status
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 clamped
Pixel Layer2 Half shell
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SCT status
Completed SCT End-Cap disk
SCT Barrel 6
(Picture taken by a star-photographer, P. Ginter,
as art-work)
(Picture taken at Oxford)
Barrel SCT ( TRT) installed
Both End-Caps ready for insertion in TRT EC C
this week, EC A in November Ready for
installation January 2007
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SCT Barrel Integration
Barrel 6 insertion into thermal shield
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TRT Barrel
Barrel TRT during insertion of the last modules
(February 2005) Now installed in cavern
Cosmics in the barrel TRT
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TRT End-Caps
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
A and B type TRT end-cap wheels fully assembled
Both TRT End-Caps are ready for integration with
the SCT
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SCT in TRT Barrel Insertion
Barrel TRT
Barrel SCT
End of February 2006 the barrel SCT was inserted
into the barrel TRT
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Cosmic track in SCT/TRT Barrel
Dead channels SCT lt 0.2 TRT lt 1.5
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Transport of SCT/TRT Barrel on 30.August 2006
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SCT/TRT barrel in its final location inside
calorimeter
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Calorimeter Layout
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27 Oct. 2004 Lowering LAr cryostat
LAr positioning
Mounting Tilecal modules
1 Dec 2004 58 Tile modules mounted
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Barrel LAr and Tile Calorimeters
A cosmic ray muon registered in the barrel Tile
Calorimeter
The barrel LAr and scintillator tile calorimeters
in the cavern in their garage position January
2005
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Barrel Toroid installation
Barrel Toroid coil transport and lowering into
the underground cavern
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The first coil was installed in October 2004
The last coil was moved into position on 25th
August 2005
Cool Down started 4 July 2006 31 August 2006 4
K Test with full current in October
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(ATLAS Christmas card 2005)
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End-Cap Toroid
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
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Muon Spectrometer Instrumentation
Precision chambers - MDTs in the barrel and
end-caps - CSCs at large rapidity for the
innermost end-cap stations Trigger 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.
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Barrel MDTs

Installation of barrel muon station (65 done)
A crucial component to reach the required
accuracy is the sophisticated alignment
measurement and monitoring system
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First cosmics registered in situ for barrel
chambers
In December 2005 in MDTs
and in June 2006 in RPCs
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First TGC Wheel fully installed
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Installation 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

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Commissioning

• 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

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The commissioning run

• Beam pipe closure end of August 2007
• LHC commissioning run with collisions at the
  injection energy (vs 900 GeV), scheduled
  November 2007
• Luminosity typically
• L 1029cm-2s-1
• The LHC will be a static machine, no ramp, no
  squeeze, to debug the machine, the detectors and
  the data processing
• A few weeks of stable running conditions at the
  injection energy

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Triggers for the commissioning running

• vs 0.9 TeV, L 1029cm-2s-1, sinel40 mb ltgt 4
  kHz interaction rate
• Commissioning the detector, the trigger, the
  offline reconstruction and analysis chains
• Data taking with loose level-1 (LVL1) single muon
  triggers (pTgt5 GeV) or minimum bias triggers
• The High Level Trigger (HLT) in pass-through mode
  for testing
• Minimum 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 (h range efficiency for
  minimum-ionizing particles multiplicity
  requirements etc.)
• Needed at very low luminosity where interactions
  per BC ltlt 1

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Event statistics for the commissioning run
30 data taking efficiency included. Efficiency
of trigger and analysis cuts included.
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Event statistics with B and Quarkonium muonic
decays
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The first physics run

• vs 14 TeV, L 1032-33cm-2s-1
• The aim is to integrate several fb-1 by the end
  of 2008.
• Many customers for the data
• Data for commissioning the detector, the trigger,
  the offline reconstruction and analysis chains
• Data samples high-pT physics studies
• Sharing of bandwidth between different triggers
• Plus control samples to understand the
  backgrounds, measure the selection efficiency,
  etc
• Data samples for B-physics studies
• Scope depends on luminosity and available HLT
  resources
• Data samples for minimum-bias physics studies
• Needed also for tuning Monte Carlo generators
  used in other physics studies

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Minimum bias on day zero?

• Why measure min bias?
• Not exactly what the LHC was built for!
• But..
• Physics measure dN/dhh0
• 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
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Event characteristics

• Event characteristics
• Non-single diffractivenon-diffractive inelastic
• Soft tracks pTpeak250MeV
• Approx flat distribution in h to h3 and in f
• Nch30 hlt2.5
• Trigger rates
• s70mb (NSD!)
• R700kHz _at_ L1031cm-2s-1
• Rapidity coverage
• Tracking covers hlt2.5
• pT problem
• Need to extrapolate by x2
• Need to understand low pt charge track
  reconstruction

h
1000 events
Reconstruct tracks with 1) pTgt500MeV 2)
d0 lt 1mm 3) B-layer hits gt 1 4)
precision hits gt 8
dNch/d?
dNch/dpT
Black Generated (Pythia6.2) Blue
TrkTrack iPatRec Red TrkTrack xKalman
M. Leyton
pT (MeV)
C. Buttar
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Low pT Min Bias Track Recon
50MeV

• 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

A.Salzburger
Elsing
400MeV
150MeV
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Tracking 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 good
• efficiencies after initial alignment
• Example taken from T.Golling
• Precision will need Zs and
• resonances to fix energy scales,
• constrain twists, etc

M.Elsing
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B cross-section at LHC

• All LHC experiments plan to measure B-cross
  section in proton-proton collisions.
• Measurements will cover different phase space
  will be complementary.
• Partial phase-space overlaps LHCb, ATLAS, CMS,
  ALICE - opportunity for cross-checks.
• Methods of measurement for low- and medium-pT
  events in ATLAS
• bb ? m6 X
• bb ? m6m3 X
• Exclusive channels B?J/y K, B0? J/y K0
• b-b correlations B?J/y X b? m

Dff J/y - fm
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Statistics for bb-events
Decay Statistics with 10 pb-1 Statistics with 100 pb-1
bb ? m6 X 40 M 400 M
cc ? m6 X 20 M 200 M
bb ? m6 m3 X 2 M 20 M
B ? J/y(m6m3) X and b ? m5 X 2 500 25 000
B?J/y K 1 700 17 000
B0? J/y K0 870 8 700
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B, J/y and ? measurements
Decay Statistics with 100 pb-1 Measurement
pp ? J/y(m6m3) 1000 k R(bb ? J/y )/R( pp ? J/y) R(pp ? U) /R( pp ? J/y)
bb ? J/y(m6m3)X 400 k R(bb ? J/y )/R( pp ? J/y) R(pp ? U) /R( pp ? J/y)
? (m6m3) 100 k R(bb ? J/y )/R( pp ? J/y) R(pp ? U) /R( pp ? J/y)
Decay Statistics or limit with 100 pb-1 Measurement today
B?mm K 23 Belle today 80?
B0? mm K0 12 Belle today 80?
Bs? mm f 9
Lb? mmL 3
Bs?mm 6.410-8 at 90 C.L. CDF currently 8.0x10-8 at 90 C.L.
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Hadronic top with 100 pb-1
3 jets with highest are used to form top
34 electron-events have exactly 1 electron
ptgt25GeV L1 trigger EM25I  
9.6 has exactly 4 jets (Cone0.4) ptgt40GeV
The fourth jet
91 etmissgt20GeV
Zhu
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Top masses
No triggerpT(elec)gt25 GeV TriggerEM25I or MU20
Leptonic top
Hadronic top
(no W in-situ calibration)
? Reconstructed top mass distributions not
affected by trigger
Pralavorio
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Conclusions

• 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/y 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/Y and ? measurements.
• Top-physics.
• Beyond Standard Model e.g. inclusive SUSY
  searches!

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Thank you!
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BACKUP SLIDES
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Sources of low-pT single and double muons
LVL1 muon trigger rates _at_ 14 TeV and 1033cm-2s-1

• 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.

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Detector configuration during the first physics
run

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