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Highlights from the Large Hadron Collider. Physics at the Terascale The LHC: brief overview and status The LHC experiments: brief overview and status. Jos Engelen CERN. gauge. x8. Standard Model and Beyond(?). H. The Higgs sector – ‘the unknown’. The Supersymmetric world? - PowerPoint PPT Presentation
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Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 1
Highlights from the Large Hadron Collider
Jos Engelen
CERN
•Physics at the Terascale•The LHC: brief overview and status•The LHC experiments: brief overview and status
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 2
Standard Model and Beyond(?)
x8
gauge
The Supersymmetric world? One supersymmetric partner for each ‘standard’ particle –the Higgs sector becomes slightly more complicated: 5 supersymmetricHiggs bosons
HThe Higgs sector – ‘the unknown’ Hqq
mqq
mllmHHZZWWgHhHhHmHL qq
qql
l
WHH )()2)(
cos21(
44)(
21
,,
222
243222
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 3
The ‘Standard Model’
is a wonderful model for describing the fundamentalparticles and fields and their interactions, it provides aquantitative description of all experimental results so far, but:
•the model invokes a mechanism for dealing with mass: it is an empirical fact that certain field particles (W, Z bosons) carry mass, incorporating this in the theory is highly non-trivial – it requires the introduction of a new field (Higgs field) and corresponding particle (‘the Higgs’): this particle has never been found by an experiment it will be at the LHC•the model would ‘go wrong’ at high energy without the Higgs particle (or other ‘new physics’)•‘unification of forces’ at very high energy could be revealed by a new trend setting in at LHC energy: ‘supersymmetry’
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 4
‘The Terascale’
Based on ‘extrapolations’ from our presentunderstanding and on quite general theoreticalinsights we expect the ‘new physics’ to manifestitself at an energy around or below 1 Tera-electronVolt = 1012 electronVolt, i.e.at the Terascale accessible at the LHC for the first time(and only at the LHC for years to come!)
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Quark Gluon Plasma
The LHC will also provide Pb Pb collisions at574 + 574 TeVallowing unique contributions to the studyof a quark gluon plasma
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 6
Accelerator and ExperimentsUndergroundcircular tunnel27 km circum-ference; 100 munderground
4 caverns forexperiments ()
x
xx
x
RF
BD
ATLAS
CMS
LHCb
ALICE
*
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Accelerator
Collisions of 7,000 GeV on 7,000 GeV protons(for reference: proton mass = 1 GeV)
Luminosity 1034 cm-2s-1
(collision rate normalized to cross section)
Innovations: ‘2 in 1’ superconducting 8.3 T dipoles (operating temperature 1.9K) focusing s.c. quadrupolesChallenges: collimation (350 MJ stored energy per beam, can melt 800 kg of copper) and furthermore the mere size of the system, e.g. more than 33,000 tonnes of ‘cold mass’, 27 km of cryogenic distribution line, etc.
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Accelerator complex
(1959)
Biggest ring = 27 km circumference
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
R&D
pre-production
industrialproduction
1232plusspares
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 10
Van streng tot kabel
NiTi filamenten, 7(geproduceerd viaextrusie)
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
In the tunnelMagnetinter-connect
Quality controlandQuality assurance
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
6 superconducting bus bars 13 kA for B, QD, QF quadrupole
20 superconducting bus bars 600 A for corrector magnets (minimise dipole field harmonics)
42 sc bus bars 600 A for corrector magnets (chromaticity, tune, etc….) + 12 sc bus bars for 6 kA (special quadrupoles)
13 kA Protection diode
To be connected:
• Beam tubes• Pipes for helium• Cryostat• Thermal shields• Vacuum vessel• Superconducting cables
Magnet Interconnect
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
In the tunnelJumper connectingcryogenicdistributionline and magnets(once every~100 m)
(early photo,tunnel practicallyempty)
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
In the tunnelBeam deliverytowardsinteractionpoint
Current distributionusingHigh TemperatureSupercondutorcurrent leads
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
LHC Status
Installation complete•cryogenic distribution line•injection lines•sc dipoles and quadrupoles; interconnect•inner triplets preparing beams for collision•RF stations (sc) for acceleration 450 GeV 7000 GeV•beam dumps•collimation•beam instrumentationHardware commissioning•cool-down complete•pressure tests •powering testsCommissioning with beam•circulating beamsColliding beams•Restart Spring 2009
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 16
The Large Hadron Collider project saw a wonderfulstart of operations on September 10, 2008:
•LINAC, Booster, PS, SPS were accelerating beam to 450 GeV for injection into the LHC•The injection lines (TI8, TI2) transported the beam to the LHC•The injection kickers sent the beam(s) into the LHC•Circulating beams, in both apertures, were established for the first time, with the whole world looking over our shoulders, in a matter of hours•The LHC experiments were ready and operational as planned and recorded beam related (timing!) data immediately•The Worldwide LHC Computing Grid was up and running
Start of Operations
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 17
Start of Operations
During the days following September 10 someunreliable (‘old’) elements of the electricalinfrastructure (transformers) had to be repaired/replaced,but the preparations for collisions continued, one othervery important milestone was passed easily, not becauseit was easy but because of excellent preparations:
the RF system captured the beam
the road to first beam-beam collisions was now fully open
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 18
Final Hardware Commissioning
The magnets in Sector (‘Octant’) 34 had not beencommissioned yet to full current for operationat 5 TeV (i.e. commissioning to 5.5 TeV)
The 7 other octants of the LHC had been commissionedto 5 TeV (and well above) without problems
On September 19 (around 11:18) an incident occurred,leading to a large Helium leak in sector 34 – cold Heliumescaped into the tunnel, the insulation vacuum was broken(up to vacuum barriers), the beam vacuum was broken(up to sector valves)
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 19
Recovery Sector 34
It is now clear that recovery of Sector 34 will takeuntil (‘into’) the planned (and obligatory) Wintershutdown – LHC operations will restart Spring 2009.A precise planning is being worked out.
The nature of the incident has been understood– it is due to an electricalfault (resistive splice in interconnect)
The loss of the insulation vacuum lead to some collateraldamage – the logistics of the repair program are beingworked out. Very importantly: diagnostic tools are being designed toavoid such problems in the future
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 20
Schedule of Experiments
The experiments will now go into ‘long shutdown’ mode,to be ready again in early Spring 2009: a more precisedate will be agreed with them as soon as this is possible
Most experiments have identified a useful and/or necessaryprogram of work of 4 – 5 months: repairs, refurbishments,improvements, additional installation work
Everybody involved in the LHC project is as motivated asever (or more motivated than ever) to overcome thistemporary setback! Everybody has reacted professionallyand with determination.
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 21
The successful start-up
The behaviorof the beams was excellent and understood
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Cross-section of LHC cryodipole
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Cooldown Status
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Cooldown Status
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
RF cavities
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
The RF cavities and transverse dampers
Courtesy Edmond Ciapala
Preparation for BeamRF synchronization in place – clocks and timing now going from SR4 to all users. Recent successful dry run tests with all users and OP group, including basic software.
Procedures for beam commissioning well defined.Longitudinal diagnostics in good shape to study and commission first beams….
Fibre-optics signal distribution from RF in SR4 to Experiments, BT & BI equipment and to CCC.
40 MHz bunch clocks, revolution frequencies,40 MHz 7TeV reference. Injection & dump kicker pulses
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Synchronisation
PSB
Re-phase withbeam ~50ms
Re-phase withbeam ~20ms
Rephase with beam: The timedifference between the targetbucket FREV and the source
bucket FREV is measured by aTDC. The TDC value then
changes the RF frequency sothat they come in line.
This takes time to complete, anddisturbs the orbit.
RF frequency isnearly fixed. Justjump to the nextbucket. This can
only happen if theSPS is empty
FillingLHC Ring 1
LHC RFSR4
R1 Bucket fromtelegram
SPS
SPS RFBA3
CPS
CPS Sourcebucket FREV
Next SPS targetbucket FREV
Timedifferenceto digitalconvertor
VCO CPS RFRF
Batch 3 Batch 4 Batch 5
Injection Kicker
OutIn
Target BucketFREV
LHC TBF LHC TBFSPS SBF SPS SBF
SB-Frev jumps tothe next LHC TB-Frev
Target bucketrevolution frequency
Kicker tail is to long to allowinserting batch 4 between batch
3 and batch 5
+-
Referencefrequency
Batch number to Bucket numberconversion
Bucket = K + h/nh = 35640 RF Buckets
n = 12 BatchesK = 121 Approx (Offset)
Courtesy Roger Bailey
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Injection Region
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
08 08 08
Friday 15:20Beam on to TI2 TEDMSI etc pulsingCycle LHC Sector 23
OP Beam down TI2 first shot
Friday 19:00
TI2 TED out, beam to TDI, kickers offGive Alice 20 minute warning before taking TED out
INJBeam on TDI after correction end TI2
Friday 21:00Kickers on, time in, position checksResolve timing issues
INJ
Interesting collaboration between timing and RF
Friday 21:40 TDI out - threading - momentum matching - beam to IR3 Jorg & team
Beam to IR3 first shot. Tweak SPS.
Courtesy Roger Bailey
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
First Trajectory
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Kick response compared with theoretical optics
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Dispersion 2-3
The trajectory of the off-momentum (1 per mil) beam. On the far left is the end of TI2 where there are no measurements. It goes through LSS2 and Alice with practically zero dispersion. In the arc there is a slight mismatch which is of no consequence and LSS3 it perfectly maps the large dispersion bump from positive to negative that is designed to stop uncaptured particles (which will be lost as the field rises since they are not accelerated) on the collimators.The vertical dispersion (bottom) is zero as it should be.
Lyn Evans – EDMS document no. 964651 33
Lyn Evans – EDMS document no. 964651
Beam on turns 1 and 2
34Courtesy R. Bailey
Lyn Evans – EDMS document no. 964651
Few 100 turns
35Courtesy R. Bailey
Lyn Evans – EDMS document no. 964651
Dump dilution sweep
36
Lyn Evans – EDMS document no. 964651
No RF, debunching in ~ 25*10 turns, i.e. roughly 25 mS
37Courtesy E. Ciapala
Lyn Evans – EDMS document no. 964651
Capture with optimum injection phasing, correct reference
38Courtesy E. Ciapala
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
The LHC experiments haveseen first ‘man made’ beam
ALICE Detector
TPC
PHOS
Muon arm
TOFTRDHMPID
PMD
ITS
ACCORDE
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Injection tests
y = 3.5326x - 12525
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
0 10000 20000 30000 40000 50000 60000
ITS multiplicity
FMD
mul
tiplic
ity
Series1Linear (Series1)
SPD/SSD, Sunday, 15.6Dump on TED
SPD hits versus bunch intensity(beam through ALICE)
FMD hits versus SPD hits(beam through ALICE)
FMD event display(1 bunch through ALICE, > 100 000 hits)
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Single turn
Double turn, beam 1 back at point 2 !
Luminosity monitor (V0)
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Trigger timing (before alignment) versus bunch numbersingle shotfor SPD, V0, beam-pickup BPTX, T0 triggers
Auto-correlation for SPD trigger, with multi-turn correlations (3564 bunch crossings)
Beam pick-upT0SPDV0
First interactions 12th September
ITS tracks on 12.9.2008
Circulating beam 2stray particle causing an
interaction in the ITS
24/10/2007 23rd RRB J. Schukraft
TPC
ParticleIdentification
Momentum Resolution
Krypton Gain Calibration
46
LHCb Spectrometer
VELO
RICH1
TT
Magnet
OT
RICH2 Calo. System
Muon System
LHCb sees tracks from the LHC injection tests
Silicon tracker
Muon chambers
VELO(Run 30933, Event 14)
SPD (provided trigger)TED events
Beam1 induced OT tracks originating close to the beam pipe
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 200849
ATLAS
45 m
24 m
ATLAS superimposed tothe 5 floors of building 40
LHCC, 24-Sep-2008, PJ
Status of ATLAS
7000 Tons
50Very first beam-splash event seen in ATLAS (as seen online in the ATLAS Control Room) on 10-Sep-2008 at 10:19
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 200851
A busy beam-halo event with tracks bent inthe Toroids from the start-up day (offline)
52
Barrel-tracks
TRT in the run 22-25 August (a cosmic shower)
Shower
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
The CMS Detector
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Calorimeters: Collimators Closed
Energy in ECAL (EE-, EB, EE+)
ECAL: Splash events provided a source for overall internal synchronization.Crystals were time aligned to within 1ns !
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
WLCG
Since CCRC08 in May the experiments have continued to run work at very high levels on the grid infrastructure and continued to keep data
transfers running at a level consistent with that expected in data taking. WLCG has seen cosmic data and also the first “events” from LHCb during
the second injection test, and data sets from all 4 experiments on Wednesday 9/10. The transfer rates all summer have been in excess of 1 GB/s more or less continuously with higher peaks (the data taking rate is
650 MB/s, twice that for safety). This, and the continuous high rate of job submission has been driven by experiment functional testing, and
more and more detector-driven stress tests.
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008
Conclusions
The LHC experiments have followedthe remarkable performance of theLHC machine with an equally remarkableperformance:
the detectors work with real beam!
Jaarvergadering NNV Secties K&H, Lunteren, November 7, 2008 57
Conclusions
Recovery of Sector 34 has the highest priority
Start-up in Spring 2009 is now the target
And then: a two phased approach to SLHC