LHC Commissioning and First LHC Commissioning and First Operation Operation

PPC 2010, July 12, 2010, Turin, ItalySteve Myers

Director for Accelerators and Technology,

CERN Geneva

(On behalf of the LHC team and international collab orators)

� The LHC(reminder)

� The last 18 months (rapidly)�The Accident�The Repair and consolidation� Initial Commissioning�Present status and plans

Topics

S. Myers QUB March 11, 2009S. Myers QUB March 11, 2009 33

Superconducting Proton Accelerator and Colliderinstalled in a 27km circumference underground tunnel (tunnel cross-

section diameter 4m) at CERNTunnel was built for LEP collider in 1985

The LHC

LHC: Some Technical Challenges

Circumference (km) 26.7 100-150m underground

Number of superconducting twin-bore Dipoles

1232 Cable Nb-Ti, cold mass 37million kg

Length of Dipole (m) 14.3

Dipole Field Strength (Tesla) 8.4 Results from the high beam energy needed

Operating Temperature (K) (cryogenics system)

1.9 Superconducting magnets needed for the high magnetic field

Super-fluid helium

Current in dipole sc coils (A) 13000 Results from the high magnetic field1ppm resolution

Beam Intensity (A) 0.5 2.2.10-6 loss causes quench

Beam Stored Energy (MJoules) 362 Results from high beam energy and high beam current1MJ melts 1.5kg Cu

Magnet Stored Energy (MJoules)/octant

1100 Results from the high magnetic field

Sector Powering Circuit 8 1612 different electrical circuits

S. Myers QUB March 11, 2009S. Myers QUB March 11, 2009 55

InterconnectionsInterconnections

During cool-down of the LHC the machine contracts by 80 metres, 10m per octant

•Vacuum continuity

•Electrical connections

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Accident of September 19Accident of September 19 thth 20082008

�� Following a very impressive startFollowing a very impressive start --up with beam on up with beam on September 10, 2008September 10, 2008

�� During a few days period without beamDuring a few days period without beam

�� Making the last step of dipole circuit in sector 34 , to Making the last step of dipole circuit in sector 34 , to 9.3kA9.3kA

�� At 8.7kA, At 8.7kA, development of resistive zone in the dipole development of resistive zone in the dipole bus bar splicebus bar splice between Q24 R3 and the neighbouring between Q24 R3 and the neighbouring dipoledipole

�� Electrical arc developed which punctured the helium Electrical arc developed which punctured the helium enclosureenclosure

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Bus bar spliceBus bar splice

Absence of soldering

Resistance 220 nOhm Bad contact with stabilizer

No sensitive detection on bus bar

Thermal runaway

Meltdown, open circuit Power converter fast discharge

Electrical arc

Fault tree [1/3]

Electro-thermal model

Observed on magnet

Fault tree [2/3]

Electrical arc

Beam pipe perforationHe vessel perforation Soot

He discharge in insulation vacuum

Contamination by sootInadequate sizing of relief devices (MCI)

Pressurization of vacuum enclosures

Mechanical damage to MLI

Contamination by MLI

ODH in tunnelBlast

Trip AUG

Loss of beam vacuum

Break vent door

Fault tree [3/3]

Pressurization of vacuum enclosures

Pressure forces on vacuum barriers

Plastic deformation of shells Buckling of bellows

Rupture of supports and ground anchors

Displacement of magnets

Mechanical damage to interconnects

Secondary electrical arcs

Damage to tunnel floor

Used to estimate max pressure reached

1313

ConsequencesConsequences

Electrical arc between C24 and Q24

M3 line

V lines

Collateral damage: secondary arcs

QQBI.27R3 M3 line

QBBI.B31R3 M3 line

1616

+ 8 cryogenics!

Phase 1 +2

Pyramid for Splice Mapping

Current in the Dipoles as function of time

Maya Pyramid

QPS team

1nΩ

Splice Mapping of Quadrupoles

20

A78.RB: Normalized Bus Segment Resistance

Every single sc splice were measured in 2009

1nΩ

Decided Scenario 2010-2011

� Run at 3.5 TeV/beam up to a integrated luminosity of around 1fb-1.

� Then consolidate the whole machine for 7TeV/beam (during a shutdown in 2012)

� From 2013 onwards LHC will be capable of maximum energies and luminosities

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Why are we limiting the beam energy to 3.5TeV in 2010-2011?

All the work we have done since November 2008 makes us certain that a repeatof September 19 can NEVER happen.

The offending connector in this incident had an estimated resistance of 220nΩ. We have measured all 10,000 inter-magnet connectors and the maximum resistance we have seen is 2.8nΩ.

BUT in April 2009, we have uncovered a different possible failure scenario which could under certain circumstances produce an electric arc in the “copper stabilizers” of the magnet interconnects

First Collisions at 7TeV cmMarch 30, 2010

March 30 2010

MOPEC003/4 Fuchsberger et alMOPEC014 White et al

30/3/201030/3/2010 11:15 injected again12:38 : At 3.5 TeV

Soon after the first Collisions

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A very good 48 hour period!

IP1&5 lumi vs squeeze

� Raw (online) lumi plots on 10 apr 2010, during the squeeze to 2m in IP1 and IP5

� Factor gained (raw numbers):� ~4.5 in Pt5 (after min scan)� ~4 in Pt1

� Not corrected for lumi decay over the ~5h of squeeze and mini scans

atlasatlas

LHC Design Bunch Intensity: Thursday 15.4.2010

� Higher intensity � Over-injection working well

� Over-injected 1.1E11, with collimators at nominal 4.5 sigma settings.

� Emittance at 1E11: 2.5 um H, 2,3 um V.

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Loss map for offLoss map for off --momentum error. All OK. See expected low leakage momentum error. All OK. See expected low leakage to experimental IR's. to experimental IR's. OK for stable beams from coll.OK for stable beams from coll.

IR1IR1

IR2IR2

IR5IR5IR8IR8

factor 10,000factor 10,000

Qualification: OffQualification: Off --momentum collimationmomentum collimation

Transverse Damper: Damping Beam Excitations

OFF ON

Crucial device to keep emittance growth

under control!

Wolfgang Hoefle et al

3131

Transverse Damper will stabilize against the Hump

Collisions with design current at 450GeV

Second fill with better lifetime conditions for B1 after RF phase loop adjustment.

Stable beams at design current per bunch at 450GeV

Closing Collimators During Ramp

LHC statusLHC status 8/6/2010

R. Assmann

Pushing Number of 2e10 Bunches

LHC statusLHC status 8/6/2010

48 hours

2 x 2e10 � 4 x 2e10 6 x 2e10 per beam

Allowed doubling the integrated luminosity for 2010

within 48 hours!

13 bunches: 3x1029 !!

LHC status LHC status -- week 20&21week 20&21

Recent progress/Changes� Until 9 June, machine time shared between

physics and machine studies.� Physics with ~2x1010 protons/bunch� Machine studies to develop 1x1011 protons per bunch

� Beam Stored energy is the metre stick: (Machine Protection)� Lost particles must end up on collimator or dump

Following discussions with the 4 spokespersons and the physics coordinator, a decision was unanimously made on 9 June to

concentrate on “Machine studies to develop 1x1011 protons per bunch” until it was operational. This meant postponing physics data

taking for around 3 weeks. (Minutes LMC 9th June)2

Getting to Stable beams at 1.1x1011.Instabilities in Collision at 3.5TeV/beam

� longitudinal emittance control� In the SPS� During the ramp in the LHC

� Transverse damper working� Collimators set up� Injection set up for new high intensity� Beam dump set up for higher intensity

� Started physics data taking under these conditions on Saturday 26th June (almost a week ahead of estimates)

Ramps for Operations set up for 1011 protons/bunch

26th June: 5x1029 with 3 bunches/beam; 1011/b

6-8x1029cm-2s-1 with 3 bunches per beam;1011/b

29th June, new record

2nd July: Colliding 6 bunches per beam; 1011/b

New Record Lumi > 1e30 cm-2 s-1

LHC statusLHC status 8/6/2010

Beam Lifetime

LHC statusLHC status 8/6/2010

Collisions

ALICE

Beam Intensity Losses

LHC statusLHC status 8/6/2010

Tune: Coherent Excitation

LHC statusLHC status 8/6/2010

Better but not perfect stability…

LHC statusLHC status 8/6/2010

Intensity Luminosity

Tuni

ng

Integrated Luminosity on 7th July

S. Myers QUB March 11, 2009S. Myers QUB March 11, 2009 4949

Latest News from this morning

Summary of Milestones thus far

� 30 March: first collisions at 3.5TeV/beam

� 19 April: order of magnitude increase in luminosity � doubling the number of particles/bunch� β * from 11 to 2m (4b/beam) L ~2x1028.� Beam lifetimes of ~1000 hours

� 22 May another order of magnitude:� 13 bunches in each beam (L~ 3x1029)

� 26 May: Design intensity bunches were brought into collision at 3.5TeV/beam.

� 2nd July peak luminosity of 1030cm-2s-1.

Presently

� From experience so far� No fundamental issue for 1e30 luminosity� Further equalize beam parameters (emittance, intensity, …) while

delivering luminosity. Try to get nominal beam and bunch parameters, including variations.

� As stability is improved, push up again on luminosity

� In addition:� Cross calibrate emittance measurement devices.� Push transverse damper into full operation in collision, however,

possibly needs noise reduction.

LHC statusLHC status 8/6/2010

Aim is for 1032 before the end of 2010 which is needed for an integrated luminosity of 1fb-1 before end of 2011

Peak lumi (in STABLE BEAMS)(modulo some possible luminometers down time...) Fills 1005-1199Fills 1005-1199

~70 days~70 days

1e32 !!1e32 !!

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The work summarized here is the result of work carried out by hundreds if not thousands of scientists, engineers and technicians both employed by CERN and very importantly by the many institutes which collaborate with CERN.It is a great personal pleasure to acknowledge the incredible contributions and dedication of such a wonderful team.

Acknowledgements

Thank you for your attention

Clamped and shunted

MOPEB042 Bertinelli et al.