OVERVIEW OF ATLAS PROJECT AND UK INVOLVEMENT

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A NEW HORIZON ATLAS at the CERN LHC
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WHERE ARE WE NOW??

• Particle Physics
• Standard Model is very successful
• 3 families of quarks and leptons 3 forces
• Gravity is not included
• High precision tests are satisfied BUT
• Theoretical difficulties
• Higgs mass is not predicted and is unstable and
  not yet found
• Involves 19 undetermined parameters
• expected to break down in the TeV range
• Astrophysics
• We only know 4 of the matter / energy in the
  universe
• Dark Matter and Dark Energy need to be identified
• Gravity does not fit well with Quantum Mechanics

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Why are there 3 families of particles?
Is the Higgs boson the origin of mass?
Why are there 4 forces?
SCIENTIFIC PUZZLES
What is Dark Matter?
Are there more than 3 space dimensions?
Why is there a matter antimatter asymmetry in
the universe?
Where does Gravity fit in?
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EXAMPLES OF NEW THEORIES

• Supersymmetry
• Introduces a spectrum of partners for all known
  particles and 5 Higgs
• Solves problem of mass stability for the Higgs
• May solve the dark matter problem
• Superstring Theory
• The best hope for combining gravity with quantum
  theory in 11 dimensions
• Predicts Supersymmetry but discovery would not be
  conclusive proof
• Still awaiting other testable predictions
• Models with Large Extra Dimensions
• May explain the weakness of gravity
• Interesting signatures including mini Black Holes

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WHAT DO WE NEED??

• The biggest accelerator in the world
• Large Hadron Collider (LHC)
• A general purpose detector to discover new
  physics unexpected as well as predicted
• ATLAS
• The group here in Liverpool are founder members
  of the ATLAS Collaboration
• One of 12 UK institutes
• A major role in the construction of the
  SemiConductor Tracker
• Detector technology the design, bonding and
  testing of modules assembly of one complete SCT
  End-cap with 988 modules

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• ?s 14 TeV (7 times higher than
  Tevatron)
• ? search for new massive particles up to m
  5 TeV
• Ldesign 1034 cm-2 s-1 (gt102 higher
  than Tevatron)
• ? search for rare processes with small s (N
  Ls )

LHC
Start Spring 2008

27 km ring used for ee- LEP machine in 1989-2000
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LHC MACHINE

• To bend 7 TeV protons around a 27 km ring 1232
  superconducting dipole magnets are needed
• 14.3m long, B 8.4T _at_ 11,700A, T 1.9K
• Altogether 9300 magnets are required
• Particles travel at 0.999999991c
• One beam has 28808 bunches each with 1.15x1011
  protons
• Total beam energy 362 MJ
• K.E. of HMS Illustrious (20ktonnes) at 11.7
  knots

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WHAT ARE THE EXPERIMENTAL PROBLEMS ?

• Need large intensity beams to see rare processes
• But this means a full interaction rate is 1 GHz
  with beam crossings every 25 nanoseconds
• Large multiplicity of particles requires good
  granularity
• Large intensities cause radiation damage
• Need to store only the interesting new physics
• Need to select data to store keeping 1 in 107
  events
• Use a multi-stage trigger system
• Still a huge amount of data to store and analyse
• need a Computing Grid

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ATLAS Collaboration
(As of the October 2005 RRB)
34 Countries 153 Institutions 1650 Scientific
Authors total (1330 with a PhD, for MO
share) New applications for CB decision UN La
Plata, U Buenos Aires (Argentina) TU Dresden, U
Giessen (Germany) U Oregon, U Oklahoma (US) New
application for CB announcement DESY, Humboldt U
Berlin (Germany) SLAC, New York U (US)
Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP
Annecy, Argonne NL, Arizona, UT Arlington,
Athens, NTU Athens, Baku, IFAE Barcelona,
Belgrade, Bergen, Berkeley LBL and UC, Bern,
Birmingham, Bologna, Bonn, Boston, Brandeis,
Bratislava/SAS Kosice, Brookhaven NL, Bucharest,
Cambridge, Carleton, Casablanca/Rabat, CERN,
Chinese Cluster, Chicago, Clermont-Ferrand,
Columbia, NBI Copenhagen, Cosenza, INP Cracow,
FPNT Cracow, Dortmund, JINR Dubna, Duke,
Frascati, Freiburg, Geneva, Genoa, Glasgow, LPSC
Grenoble, Technion Haifa, Hampton, Harvard,
Heidelberg, Hiroshima, Hiroshima IT, Indiana,
Innsbruck, Iowa SU, Irvine UC, Istanbul Bogazici,
KEK, Kobe, Kyoto, Kyoto UE, Lancaster, Lecce,
Lisbon LIP, Liverpool, Ljubljana, QMW London,
RHBNC London, UC London, Lund, UA Madrid, Mainz,
Manchester, Mannheim, CPPM Marseille,
Massachusetts, MIT, Melbourne, Michigan, Michigan
SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal,
McGill Montreal, FIAN Moscow, ITEP Moscow, MEPhI
Moscow, MSU Moscow, Munich LMU, MPI Munich,
Nagasaki IAS, Naples, Naruto UE, New Mexico,
Nijmegen, BINP Novosibirsk, Ohio SU, Okayama,
Oklahoma, LAL Orsay, Osaka, Oslo, Oxford, Paris
VI and VII, Pavia, Pennsylvania, Pisa,
Pittsburgh, CAS Prague, CU Prague, TU Prague,
IHEP Protvino, Ritsumeikan, UFRJ Rio de Janeiro,
Rochester, Rome I, Rome II, Rome III, Rutherford
Appleton Laboratory, DAPNIA Saclay, Santa Cruz
UC, Sheffield, Shinshu, Siegen, Simon Fraser
Burnaby, Southern Methodist Dallas, NPI
Petersburg, Stockholm, KTH Stockholm, Stony
Brook, Sydney, AS Taipei, Tbilisi, Tel Aviv,
Thessaloniki, Tokyo ICEPP, Tokyo MU, Toronto,
TRIUMF, Tsukuba, Tufts, Udine, Uppsala, Urbana
UI, Valencia, UBC Vancouver, Victoria,
Washington, Weizmann Rehovot, Wisconsin,
Wuppertal, Yale, Yerevan
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Construction, integration and installation of the
ATLAS detector
ATLAS superimposed to the 5 floors of building 40
Diameter 25 m Barrel toroid length
26 m End-cap end-wall chamber span 46
m Overall weight 7000 Tons
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The Underground Cavern at Pit-1 for the ATLAS
Detector
Length 55 m Width 32 m Height 35 m
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An Aerial View of Point-1
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Physics example
H ? ZZ ? 4 ?

Gold-plated channel for Higgs discovery at LHC

Simulation of a H ? ?? ee event in ATLAS
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Magnet System
Central Solenoid
2T field with a stored energy of 38
MJ Integrated design within the barrel LAr
cryostat
The solenoid has been inserted into the LAr
cryostat at the end of February 2004, and it was
tested at full current (8 kA) during July 2004
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Toroid system
Barrel Toroid parameters 25.3 m length 20.1 m
outer diameter 8 coils 1.08 GJ stored energy 370
tons cold mass 830 tons weight 4 T on
superconductor 56 km Al/NbTi/Cu conductor 20.5 kA
nominal current 4.7 K working point
End-Cap Toroid parameters 5.0 m axial length
10.7 m outer diameter 2x8 coils 2x0.25 GJ
stored energy 2x160 tons cold mass 2x240 tons
weight 4 T on superconductor 2x13 km Al/NbTi/Cu
conductor 20.5 kA nominal current 4.7 K working
point
Barrel Toroid 8 separate coils
End-Cap Toroid 8 coils in a common cryostat
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Barrel Toroid coil transport and lowering into
the underground cavern
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The first coil was installed in October 2004
The coils have been cooled down and run
together at the full excitation current
The last coil was moved into position on 25th
August 2005
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Inner Detector (ID)
The Inner Detector (ID) is
organized Into four sub-systems Pixels
(0.8 108 channels) Silicon Tracker (SCT) (6
106 channels) Transition Radiation Tracker
(TRT) (4 105 channels)
Simulation of Higgs gt 4 muons as seen in the
Inner Detector
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PIXELS

• The system consists of three barrels at average
  radii of 5 cm, 9 cm, and 12 cm (1456 modules)
  and three disks on each side, between radii of 9
  and 15 cm (288 modules)

Two completed Pixel disks, each with 2.2 M
channels
One half of a pixel barrel
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Pixel Sensor

• Each module is 62.4 mm long and 21.4 mm wide,
  with 46080 pixel elements read out by 16 chips.
• The 80 million pixels cover an area of 1.7 m2
• Spatial resolutions
• sRf 12 mm, sZ66 mm, sR77 mm

Pixel module prototype
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SILICON TRACKER (SCT)

• The SCT system is designed to provide eight
  precision measurements per track
• It is constructed using 4088 silicon micro-strip
  modules arranged as 4 barrels in the central
  region and 2 x 9 annular wheels in the forward
  region

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• Modules consist of 4 (2) detectors mounted on a
  baseboard (barrel) or spine (forward) consisting
  of Thermal Pyrolytic Graphite AlN and /or Be0
  ensuring good thermal performance
• The kapton hybrids are mounted on carbon-carbon
  substrates
• Modules have 1526 binary readout channels per
  module
• Spatial resolutions srf 16 mm, sz (sR) 580mm

Barrel Module Forward Modules
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Silicon Barrel Tracker
All four barrel cylinders were assembled in
Oxford and shipped to CERN
Assembly of the four barrel cylinders at CERN
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ID integration and commissioning at the surface
SCT acceptance tests (each barrel was fully
tested)
Barrel Total Channels Total Defects
3 589824 1483
4 737280 841
5 884736 1818
6 1032192 5720
Total 3244032 9862
Total of 99.7 of all channels fully functional
SCT barrel during acceptance test
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Insertion of barrel SCT into TRT
The four integrated SCT barrels about to be
inserted into the TRT
Insertion completed, February 15th 2006
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A cosmic track seen in both SCT and TRT
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Insertion of the Barrel ID into ATLAS
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SCT End-cap C

• The next few slides show the assembly of End-cap
  C here in Semiconductor Centre on the ground
  floor of the Oliver Lodge Laboratory

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Bonding and testing End-cap modules in Liverpool
Module bonding
Module testing
Module metrology
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• Mounting modules onto discs in Liverpool

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Close up view
A completed end-cap SCT disc
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Mounting 9 discs into the End-cap
Insertion of the last SCT end-cap disk in Endcap
C
A total of 99.73 channels are fully
functional 988 modules in total (1.52M channels)
Insertion of the first disc
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Endcap C arrives at CERN
Endcap C in SR1
Unloading
Inside view
Transfer to SR1
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• Completed End-cap C

Fitting the thermal enclosure
Inserting the end-cap into the TRT
The commissioning of the combined system is now
complete
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TRANSITION RADIATION TRACKER (TRT)

• Straw tracker
• 50,000 in barrel
• 320,000 in endcaps
• Gas Mixture
• Xe,CO2,O2 (70,27,3)
• Barrel radial coverage
• 56cm -107 cm
• Endcap radial coverage
• 64cm 103 cm
• Drift time measurements
• Transition Radiation detection
• Average of 36 points on a track

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TRT End-caps
Completed TRT A and B wheels for end-cap C
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Two examples of cosmic rays registered in the
barrel TRT in the Inner Detector surface clean
room facility SR1
Example 1
Example 2
Barrel TRT during insertion of the last modules
(February 2005)
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LAr and Tile Calorimeters
Tile barrel
Tile extended barrel
LAr hadronic end-cap (HEC)
LAr EM end-cap (EMEC)
LAr EM barrel
LAr forward calorimeter (FCAL)
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LAr EM Barrel Calorimeter After
many years of module constructions, the barrel EM
calorimeter was installed in the cryostat, and
after insertion of the solenoid, the cold vessel
was closed and welded in 2004 A successful
complete cold test (with LAr) was made during
summer 2004 in hall 180 at CERN (dead channels
much below 1)
LAr barrel EM calorimeter module at one of the
assembly labs
LAr barrel EM calorimeter after insertion into
the cryostat
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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
have been since January 2005 in the cavern in
their garage position (on one side, below the
installation shaft)
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November 4th 2005 Calorimeter barrel after its
move into the center of the ATLAS detector
Commissioning of the LAr calorimeter is underway
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LAr End-Caps
Surface cold tests of both End-caps with LAr are
finished, with very good results (dead channels
well below 1) Now installed in the cavern inside
the extended barrel Tile calorimeter
FCAL A before insertion
End-Cap cryostat A before the insertion of the
FCAL and closure
End-Cap A during the surface cold tests
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Endcap C assembled and moved close to the barrel
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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 A
crucial component to reach the required accuracy
is the sophisticated alignment measurement and
monitoring system
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First cosmics muons registered in the
stations installed in the bottom sector of the
spectrometer
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Installation of the Muon Big Wheels

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TRIGGER AND DATA ACQUISITION

• How do we reduce the event rate to select and
  store interesting events only?
• How do we cope with the huge amount of data
  gathered?

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Trigger, DAQ and Detector Control
Trigger
DAQ
Calo MuTrCh
Other detectors
40 MHz
LV L1
2.5 ms
Lvl1 acc 75 kHz
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The DATA Handling Problem

• The LHC Experiments will produce 15 Petabytes of
  data per year
• 15,000,000 Gigabytes
• A stack of 23M CDs 20km high!!
• A huge amount of data to analyse
• A huge amount of simulation is required
• The answer is to set up a world-wide computing
  grid linking processors and storage facilities
• Need to be able to transmit huge quantities of
  data around the world
• The Grid is the next step forward after the World
  Wide Web (Tim Berners-Lee, CERN)

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LCG Computing Resources (May 2005, growing!)
Number of sites is already at the scale expected
for LHC - demonstrates the full complexity of
operations
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Search for the Higgs boson
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Supersymmetric particles and dark matter
This particle (neutralino) is a good
candidate for the universe dark matter
Neutralino mass can be measured to 10 ? SUSY
discovery and neutralino mass measurement at LHC
can solve problem of universe cold dark matter
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If theories with Extra-dimensions are true, mini
black holes could be abundantly produced and
observed at the LHC.
Simulation of a black hole event with MBH 8
TeV in ATLAS
They decay immediately ? harmless .
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Summary
The LHC and ATLAS (CMS) offer very exciting
possibilities for new discoveries All
physicists working on ATLAS rely on the same
knowledge students acquire in their undergraduate
courses such as electromagnetism,
thermodynamics, mechanics, quantum mechanics,
relativity, particle physics, solid state
physics, etc. etc. CERN visits prove to be very
popular with schools The fascination of the
physics concepts involved and the sheer grandeur
of the accelerators and experiments can motivate
pupils with a great interest in the subject
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Standard Model