Status of the LHC accelerator

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Status of the LHC accelerator

• Rüdiger Schmidt - CERN
• KET November 2005
• Bad Honnef

The LHC injector complex The LHC machine Hardware
commissioning Operation und Machine
Protection Conclusions
On behalf of the CERN staff and the outside
collaborators
2
Interconnection of beam tubes
Cryogenic distribution line
On behalf of the CERN staff and the outside
collaborators
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The LHC injector complex
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The CERN accelerator complex injectors and
transfer
Beam 2
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LHC
4
6
Beam 1
Extraction
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3
2
SPS
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TI8
TI2
1
Booster
protons
LINACS
CPS
Ions
High intensity beam from the SPS into LHC at 450
GeV via TI2 and TI8 Transfer lines 2 ? 3
km LHC accelerates from 450 GeV to 7 TeV
LEIR
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LHC accelerator
LHC Main Systemsfor hardware commissioniongSupe
rconducting magnetsCryogenicsVacuum
systemPowering
Progress on LHC dashboards http//lhc-new-homepage
.web.cern.ch/lhc-new-homepage/DashBoard/index.asp
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providing 1232 LHC dipole magnets

• fabrication of cables
• fabrication of cold mass
• cryostating
• testing at 1.9 K
• installation in tunnel
• commissioning
• operation with beam

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Superconducting cable Type 1
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Dipole cold masses
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Cryodipole overview
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First cryodipole lowered on 7 March 2005
Only one access point for 15 m long dipoles, 35
tons each
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Transport in the tunnel with an optical guided
vehicleabout 1600 magnets to be transported for
15 kmat 3 km/hour
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Cryogenic distribution line
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Cryogenic distribution line in the LHC tunnel
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Status summary

• Magnet production well advanced
• Installation in progress, more than 100
  cryomagnets have been installed in Sectors 8-1,
  4-5 7-8, this must accelerate (on the critical
  path)
• Cryogenics
• large part finished and operational (e.g.
  cryoplants)
• QRL installed in Sectors 7-8, 8-1 4-5 by end of
  2005, in progress in 3-4 5-6
• QRL commissioning started
• Other systems (RF, Beam injection and extraction,
  Beam instrumentation, Collimation, Interlocks,
  Controls)
• essentially on schedule

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Hardware commissioning
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Hardware commissioning Commissioning of the
technical systems

• Safe commissioning of all technical systems that
  do not require beam
• 1232 main dipoles 3700 multipole corrector
  magnets
• 392 main quadrupoles 2500 corrector magnets
• 26 km cryogenic distribution line
• 26 km cryogenic magnets
• 4 vacuum systems, each 27 km long
• gt 1700 magnet powering circuits with power
  converters (60A 13000 kA)
• Quench protection and powering interlock systems
• gt 10000 electronics crates for operation and
  protection

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Energy stored in magnets at 7 TeV 10 GJoule
Airbus 380 The energy stored in the
LHC magnet system corresponds to the energy of an
A380 at 700 km/hour
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• Powering system commissioning startedPower
  converters installed and commissioning on short
  circuits started in tunnel
• 81 power converters in UA83
• 156 kA and 1.2 MW dissipated PCs and Cables

Cryogenic system Cryoplant commissioning well
advancedTunnel cryogenics commissioning started
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Power converter commissioning, F.Bordry, 11-2005
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Location UA83 (Beginning) Equipt
type LHC2-4-6-8kA SP1 TC 46 conf.
90 Date 2005-10-13 11h00
F.Bordry, 11-2005
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Cryogenic system
surface
tunnel
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Cool down of the cryogenic distribution line
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Operation and machine protection
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Beam commissioning Commissioning of the beam
systems

• Safe commissioning of all systems that require
  beam
• Injection system
• Extraction (beam dumping) system
• Beam monitoring
• 4000 beam loss monitors and 1000 beam position
  monitors
• Many other monitors (beam current, beam size, .)
• RF system
• Beam interlock system
• Collimation system

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Energy stored in one beam at 7 TeV 362 MJoule

• Kugelstossen
• The energy of one shot (5 kg) at 800 km/hour
  corresponds to
• the energy stored in one bunch at 7 TeV.
• There are 2808 bunches.
• Factor 200 compared to HERA, TEVATRON and SPS.

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SPS experiment Beam damage at 450 GeV

• Controlled SPS experiment
• 8?1012 protons clear damage
• beam size sx/y 1.1mm/0.6mm
• above damage limit
• 2?1012 protons
• below damage limit

25 cm
6 cm
0.1 of the full LHC beams
V.Kain et al
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Protection and Beam Energy

• A small (lt10-3) fraction of beam can cause damage
• Very efficient protection systems throughout the
  cycle are required
• A tiny (lt10-7) fraction of beam can quench a
  magnet
• Very efficient beam cleaning is required
• Sophisticated beam cleaning with about 40
  collimators per beam, each with two jaws, in
  total about 80 collimators and beam absorbers
  (first phase of LHC)

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The LHC Phase 1 Collimator
Vacuum tank with two jaws installed
Designed for maximum robustness Advanced Carbon
Composite material for the jaws with water
cooling!
R.Assmann et al
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Proton luminosity running Parameters
HSM -gt 4 l (MHiggs 140-155 GeV and 190-450
GeV) can be discovered with 4 fb-1 Some
supersymmetry can be discovered at more modest
luminosities 1 fb-1 Potential for
b-physics right from startup
(300 hours _at_ ltLgt of 1033 cm-2 s-1 1 fb-1)

• Machine parameters
• Bunch intensity
• Distance between two bunches (number of bunches)
• Beta function (beam size) at interaction point
• Experiments
• Will make use of any beam for detector
  commissioning
• Minimize event pileup early on (go to 25 ns as
  soon as possible)
• (My guess..) Operate safely has priority

- From Chamonix XIV -
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Proposal for early proton running

• Pilot physics run with few bunches
• No parasitic bunch crossings
• Machine de-bugging no crossing angle
• 43 bunches, unsqueezed, reduced intensity
• Push performance (156 bunches, partial
  squeeze in 1 and 5, push
  intensity)
• 75 ns operation
• Establish multi-bunch operation
• Relaxed machine parameters (squeeze and crossing
  angle)
• Push squeeze and crossing angle
• 25 ns operation (Phase I collimators partial
  beam dump)
• Needs scrubbing for higher intensities ( ib gt 3 -
  4 1010 )
• 25 ns operation
• Push towards nominal performance

R.Bailey
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Conclusions
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Recalling LHC status and challenges

• Concentrating on short term goals, get one sector
  installed and commissioned.
• The more global situation will be reviewed with a
  view to giving in April 2006 a more precise date
  for the completion of the machine
• Hardware commissioning with help of many external
  institutes

Fabrication of equipment
Installation
LHC hardware commissioning
LHC Beam commissioning
1 2 3 4 5 6 7 8 9 10 11 12
1 2 3 4 5 6 7 8 9 10 11 12
1 2 3 4 5 6 7 8 9 10 11 12
1 2 3 4 5 6 7 8 9 10 11 12
2005
2004
2006
2007
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Conclusions

• The LHC is a global project with the world-wide
  high-energy physics community devoted to its
  progress and results
• As a project, it is much more complex and
  diversified than the SPS or LEP or any other
  large accelerator project constructed to date

Machine Advisory Committee, chaired by Prof. M.
Tigner, March 2002

• We recognize that the planned schedule is very
  aggressive, given the complexity and potential
  for damage involved in the initial phases of
  operation.
• It will be important to understand the
  performance of the machine protection system, the
  collimation system and the orbit feedback system
  as well as cycle repeatability and adequate
  beta-beat control before proceeding to run with
  significant stored beam energy. Pressure to take
  shortcuts must be resisted.

Machine Advisory Committee, chaired by Prof. M.
Tigner, June 2005
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Acknowledgement

• The LHC accelerator is being realised by CERN in
  collaboration with institutes from many countries
  over a period of more than 20 years
• Main contribution come from the USA, Russia,
  India, Canada, special contributions from France
  and Switzerland
• Industry plays a major role in the construction
  of the LHC
• Thanks for the material from
• R.Assmann, R.Bailey, F.Bordry, L.Evans,
  B.Goddard, M.Gyr

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Is everything always going smoothly? Not really.

• I am convinced that for a project such as the
  LHC, considering the
• complexity
• uniqueness
• novelty
• difficulties will always be encountered.
• However, it is important that such difficulties
  are identified, addressed, and mastered.
• This is required
  to make a project success

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Conclusions
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LHC hardware commissioning

• Qualification for operation of the individual
  systems of a sector (vacuum, cryogenics, quench
  protection, interlocks, powering, etc.)
• Each (sub-)sector will be commissioned as a whole
  up to the powering to nominal current of all the
  electrical circuits.
• Validation and specific studies will be
  carried-out on the first commissioned sector.

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Some references

• Accelerator physics
• Proceedings of CERN ACCELERATOR SCHOOL (CAS),
  http//schools.web.cern.ch/Schools/CAS/CAS_Proceed
  ings.html
• In particular 5th General CERN Accelerator
  School, CERN 94-01, 26 January 1994, 2
  Volumes, edited by S.Turner
• Superconducting magnets / cryogenics
• Superconducting Accelerator Magnets, K.H.Mess,
  P.Schmüser, S.Wolff, World Scientific 1996
• Superconducting Magnets, M.Wilson, Oxford Press
• Superconducting Magnets for Accelerators and
  Detectors, L.Rossi, CERN-AT-2003-002-MAS (2003)
• LHC
• Technological challenges for the LHC, CERN
  Academic Training, 5 Lectures, March 2003 (CERN
  WEB site)
• Beam Physics at LHC, L.Evans, CERN-LHC Project
  Report 635, 2003
• Status of LHC, R.Schmidt, CERN-LHC Project Report
  569, 2003
• ...collimation system.., R.Assmann et al.,
  CERN-LHC Project Report 640, 2003
• LHC Design Report 2003

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Reserve Slides
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Regular arc Magnets
1232 main dipoles 3700 multipole corrector
magnets 392 main quadrupoles 2500 corrector
magnets 26 km cryogenic distribution line 26 km
cryogenic magnets 4 vacuum systems, each 27 km
long 1800 magnet powering circuits with power
converters (60A 13000 kA) gt 10000 electronics
crates for operation and protection
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Regular arc Cryogenics
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Regular arc Vacuum
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Regular arc Electronics
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Commissioning of the technical systems Hardware
commissioning

• Definition of the procedures, their sequencing,
  the refinement of the time required for the
  commissioning
• Identification of the conditions required to
  start, those required during the commissioning
  and the conditions which determine the end of the
  commissioning
• Commissioning and qualification of the individual
  systems (vacuum, cryogenics, interlocks, magnet
  protection, powering, etc).
• Following-up work of the assemblers and the teams
  checking their systems, to ensure that conditions
  for hardware commissioning are present
  (infrastructure, assembly, safety)
• Coordinating and carrying-out hardware
  commissioning in the time frame allocated by the
  General Construction and Installation Schedule
• Carrying-out validation and specific studies

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LHC magnetic cycle
energy ramp
coast
coast
7 TeV
start of the ramp
injection phase
preparation and access
450 GeV
L.Bottura
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LHC magnetic cycle - beam injection
beam dump
energy ramp
coast
coast
7 TeV
start of the ramp
injection phase 12 batches from the SPS (every 20
sec) one batch 216 / 288 bunches
450 GeV
L.Bottura
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Beam lifetime with nominal intensity at 7 TeV
Failures will be a part of the regular operation
and MUST be anticipated
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End of data taking in normal operation Beam Dump

• Luminosity lifetime estimated to be approximately
  10 h (after 10 hours only 1/3 of initial
  luminosity)
• Beam current somewhat reduced - but not much
• Energy per beam still about 200-300 MJ
• Beams are extracted into beam dump blocks

• The only component that can stand a loss of the
  full beam is the beam dump block - all other
  components would be damaged
• At 7 TeV, fast beam loss with an intensity of
  about 5 of one single nominal bunch could
  damage superconducting coils
• In case of failure beam must go into beam dump
  block

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Schematic layout of beam dump system in IR6
Septum magnet deflecting the extracted beam
Beam 1
H-V kicker for painting the beam
Q5L
Beam Dump Block
Q4L
about 700 m
Fast kicker magnet
Q4R
about 500 m
Q5R
Beam 2
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Dumping the LHC beam
beam absorber (graphite)
about 8 m
about 35 cm
concrete shielding
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Full LHC beam deflected into copper target
Copper target
2808 bunches
2 m
Energy density GeV/cm3 on target axis
Target length cm
N.Tahir (GSI) et al.
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Operational margin of a superconducting magnet
Applied Magnetic Field T
Applied magnetic field T
This is about 1000 times more critical than for
TEVATRON, HERA, RHIC
Bc critical field

Tc critical temperature
9 K
Temperature K
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56.0 mm
- 3? 1.3 mm
Beam /- 3 sigma
Beam in vacuum chamber with beam screen at 7 TeV
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Dipole magnets for the LHC
1232 Dipolmagnets Length about 15 m Magnetic
Field 8.3 T Two beam tubes with an opening of 56
mm
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SECTOR 8-1
ELECTRICAL QUALITY ASSURANCE
COOLDOWN
POWERING TESTS
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LHC Layout eight arcs (sectors) eight long
straight section (about 700 m long)
Beam dump blocks
IR5CMS
IR6 Beam dumping system
IR4 RF Beam instrumentation
IR3 Momentum Cleaning (warm)
IR7 Betatron Cleaning (warm)
IR8 LHC-B
IR2ALICE
IR1 ATLAS
Injection
Injection
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Global requirements on the machine

• Highest energy proton collisions for ATLAS / CMS
• Nominal luminosity 1034 cm-2 s-1 in points 1 and
  5
• Highest energy proton collisions for LHCb
• Nominal luminosity 5 1032 cm-2 s-1 in point 8
• Proton collisions _at_ various energies for ALICE
• Nominal luminosity 1030 cm-2 s-1 in point 2
• Ion collisions _at_ various energies for ALICE
• Nominal luminosity 1027 cm-2 s-1 in point 2
• ATLAS and CMS will also take data
• Proton collisions _at_ various energies for TOTEM

Proton luminosity running
Dedicated operation
Dedicated operation
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TI 8 Beam spot at end of line
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Transfer on jacks
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Preparation of interconnect
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Repair of QRL modules at CERN
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Repair of special QRL elements at CERN
http//lhc.web.cern.ch/lhc/LHCnews/repairs20and2
0cooldown_E.pdf
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Livingston type plot Energy stored magnets and
beam
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56.0 mm
Collimators at 7 TeV, squeezedoptics
1 mm
R.Assmanns EURO
/- 8 sigma 4.0 mm
Example Setting of collimators at 7 TeV - with
luminosity optics Beam must always touch
collimators first !