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Status and Outlook of the LHC
Enrico Bravin - CERN BE-BI
SPring-8 visit seminar26 June 2017
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Outlook• Overview of LHC
• Objectives for run2
• Parameters for 2016/2017 and differences w.r.t. 2015
• Summary of commissioning and operation
• Performance and achievements of 2016 and 2017
• Peek at 2018 and beyond
3
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The Large Hadron Collider• Double ring of 27 km
circumference • Twin aperture superconducting
magnets • Designed to collide protons (and
heavy ions) at high energy (7 TeV) and high luminosity (1034 cm-2 s-1)
• 4 interaction points • LHC energy limited to 6.5 TeV by
the need to retrain the magnets • 200 quenches were needed to
reach 6.5 TeV • 300 more will be needed to
reach 7 TeV (postponed 2020)4
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LHC and injectors
5
Protons • Linac-2 50 MeV • Booster 1.4 GeV • PS 25 GeV • SPS 450 GeV • LHC 7 TeV
208Pb82+ • Linac-3 4.5 MeV/u • LEIR 72 MeV/u • PS 5.9 GeV/u • SPS 177 GeV/u • LHC 2.76 TeV/u
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Beam parameters
6
2012 2015 2016 2017 2018 Design
Energy [TeV] 4 6.5 6.5 6.5 6.5 7
Ibunch 1.7E+11 1.2E+11 1.1E+11 1.2E+11 1.2E+11 1.15E+11
Bunch spacing [ns] 50 50 / 25 25 25 25 25
Beta* [m] 60 80 40 40 *33 55
Crossing angle [urad] 290 290 370/280 300/240 340 290
# of bunches 1374 2244 2220 2556 2556 2808
Emittance [mm mrad] 3 3 2 2 2 3.5
Peak Luminosity [cm-2s-1] 7.7E+33 5E+33 1.4E+34 *1.7E34 *1.9E34 1E+34
Integrated Luminosity [fb-1] 23.1 4.5 40 *45 *45
L =N2
b frevkb4⇡"�⇤ · 1q
1 + (�xing
�s
2�xing
)2
* estimated
Run 2Run 1
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Objectives for Run 2 • Run 2 main objective: 100 fb-1 p-p for ATLAS and CMS at
Ecm ≥ 13TeV
• 2015: Recommission the machine after LS1 at Ebeam= 6.5TeV
• Target 5 fb-1
• 2016: p-p production + Pb-p run
• Target p-p 25 fb-1
• 2017-2018: p-p (+ Pb-Pb in 2018)
• Target p-p 45 fb-1/y
7
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Changes 2015 → 2016• Smaller beta* from 80cm to 40cm → higher luminosity
• New combined ramp & squeeze (3m)→ shorter cycle
• Better handling of e-cloud effects→ mitigate transients, reduced movement of triplet in IR8
• Changed BLM thresholds → minimise dumps due to UFOs
• BCMS beams → smaller transverse emittances → higher luminosity
8
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Changes 2016 → 2017• Replaced one superconducting dipole, thermal cycle of sector
12, potential e-cloud and UFO surge
• New optics (Achromatic Telescopic Squeeze) potential for beta* < 40 cm (HL-LHC baseline optics)
• Dynamic crossing angle during the fill 300 to 240 urad → higher luminosity
• Improved combined ramp & squeeze (1m)→ shorter cycle
• Fixed limitations with SPS and injection kicker vacuum → longer bunch trains (144 bpi, more bunches) and higher bunch intensity, higher L
9
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Commissioning milestones 2016
10
Powering tests
HW check out
Low intensity injection
Low intensity combined ramp and squeeze
Low intensity squeeze
First beam March 25
First CR&S March 26
First squeeze March 26
Start March 4 End March 21
YETS - Many interventions on many systems
Ended on March 4
BIS loop closed March 23
Nominal intensity
Combined ramp and squeeze
Squeeze
Bunch trains injection
First collisions
First stable beams
Physics Intensity ramp-up
CR&S on April 6
Started operation with nominals March 29Injection
First collisions April 8
72b April 21
April 23 3b+3b April 24 12b+12b
2040b June 1
Included special bump in IP5 to increase dispersion in TOTEM
Corrections of Optics, Q, Q`, C-
Collimators setup
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Commissioning milestones 2017
11
Powering tests
HW check out
Low intensity injection
Low intensity combined ramp and squeeze
Low intensity squeeze
First beam April 29
First CR&S to 1m April 30
First squeeze to 40cm May 1
Start March 31 End April 26
EYETS - Many interventions warm-up of S12
Ended on April 14
BIS loop closed April 28
Nominal intensity
Combined ramp and squeeze
Squeeze
Bunch trains injection
First collisions
First stable beams
Physics Intensity ramp-up
CR&S on May 12
Started operation with nominals May 4Injection
First collisions May 12
72b May 26
May 23 3b+3b May 24 12b+12b
2029b June 20
Corrections of Optics, Q, Q`, C-
Collimators setup
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Combined Ramp & Squeeze
12
CR&S Squeeze
11m
2016 3m 2017 1m
40cm
10m
ATLAS & CMS
LHCb
ALICE
Beta
* [dm
]
6m
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Possible performance limitations• Unidentified laying object (ULO)
• Reduces available aperture
• Unidentified falling objects (UFO) • Trigger beam dumps and magnet quenches
• Electron cloud • Limits number of bunches (vacuum, thermal load) • Instabilities: losses, degraded beam quality
• Hardware faults rate • Fault tracking tools (identify critical systems) • Consolidations (using fault tracking as input) • R2E project (SEU almost gone)
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UFOs• Small particles (~10μm) falling onto the beam
generating showers • Source and mechanism not fully understood yet • 2015: 21 UFO-related dumps, including 3 quenches
(ULO events not included) • In 2016 increased threshold of BLMs
• Expected increase of UFO-induced quenches (~+1) • Expected decrease of UFO-induced dumps(~-10)
• 2016: 21 UFO-related dumps including 3 quenches14
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Evolution of UFOs
15
2015 2016
Time
• There is a clear conditioning effect • Not known if conditioning will be lost after venting • At the present rate UFOs are under control
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Electron cloud• Electron liberated on the vacuum chamber are accelerated by
the p+ beam • Accelerated electrons impact on the vacuum chamber
liberating more electrons • If the SEY is high, and the bunch spacing short, it turns into an
avalanche producing heat load on the cold beam screens and trigger beam instabilities
• electron bombardment reduces the SEY (scrubbing)
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e-cloud in 2016
17
Cryo limit 160 w/hc
Modest effects of e-cloud during 2016 due to the limitation in bunch current and short batches
Courtesy G. Iadarola
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e-cloud in 2017 “Scrubbing” run
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Sector 1-2 back where it was in 2016
19
Friday Sunday
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Availability
20Courtesy B. Todd
6 June → 18 September Excellent availability!
Almost 50% of fills dumped by OP
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Fault analysis
21Courtesy B. Todd
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Other limitations in 2016• Start of the run affected by few important faults
• Some generated long downtimes
• 66kV transformer IP8, POPS, PS MPS, water flooding Pt.3
• Some imposed limitations throughout the year
• LHC dump B1 N2 leak (in the shadow of other limitations)
• SPS internal dump (TIDVG) (no 144b/288b trains)
• Bad vacuum around injection kicker of B2
• max total current for B2 limited to ~2.4E14p (e-cloud)
22
14 April - LHC dump B1 25 April - SPS dump 27 April – POPS down 29 April marteen 20 May - PS MPS 21 June - Water Pt. 3
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Standard vs BCMS beams in the PS
23
Standard 72b batch εxy~2.5μmIbunch < 1.3E11
BCMS 48b batch εxy~1.5μmIbunch < 1.3E11
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Beam structure
24
PS batch72b
SPS batch288b
SPS batch144b
3μsAbort gap
26.7km, 89μs, 3564 25ns slots, max 2800 bunches
• The LHC injection gap is ~900ns while the SPS injection gap is ~200ns
• The maximum number of bunches in the LHC depends on the number of batches per SPS injection • 72b / inj. → max 2040b • (2 x 48b) / inj. → max 2220b (2076b) • (4 x 72b) / inj. → max 2800b
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LHC performance 2016
25
From end of June LHC operated consistently above design peak luminosity
Steady production from beginning of June
260 MJ/beam
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Production 2016
26
Astonishing integrated luminosity achievement
Fast ramp-up after each configuration change Steady peace through the year
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Operation cycle
27
Turnaround3h is technically the shortest value
Courtesy B. Todd
Almost half of the fills ended by operators We can finally decide the length of fills!
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Heavy ion run 2016 summary
• p - Pb @ 5 teV c.m. for ALICE
• Very long fills at levelled luminosity
• Record fill of 37 hours in stable beams
• p - Pb and Pb - p @ 8 TeV c.m.
• Increased bunch intensity of ions and protons
• Peak luminosity of 8E29 cm-2s-1, a factor 7.8 better than “design”
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HI run 2016 goals and results
29
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LHC as tide and earth quake monitor
30
• The long and fills at 4 TeV provided a unique opportunity to monitor the earth tides with the LHC during a week around full moon.
• The model scale is defined by LEP data scaled to LHC. • New Zealand 7.8 MW earthquake of 11:02 2016.11.13 UTC clearly visible
LHC orbit 13:30 2017.11.06 CET
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Special operation• Van der Meer scans for luminosity calibration
• Full VdM scans on 17, 18, 27 May for all experiments • Partial scans and studies here and there
• Large beta* run for forward physics (ALFA and TOTEM) • 19-22 September, very successful
• Plus many ad hoc cycles during the 20 days of MDs • Partially with HL-LHC in view, partially to test
improvement already applied
31
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2016 2017
~ Same days of p-p physics
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Status of 2017 run
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Long term LHC plan
34
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Conclusions• Despite some troublesome events 2016 has been a wonderful year at the LHC
• Excellent machine availability/reliability as never before
• UFO, e-cloud, faults under control
• Despite not pushing parameters too hard due to limitations delivered more than 40fb-1 to ATLAS and CMS
• Big progress in understanding and controlling the machine
• Fast start-up in 2017 shows that the machine, the people and the tools are mature
• Peak luminosity of 2016 already surpassed after only few weeks of physics in 2017
• Established a solid base for the coming years
35
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The End
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e-cloud studies• Several fills with same
conditions during the year to quantify conditioning (modest)
• 3 fills with 72bpi and increasing bunch intensity
• Large differences between sectors not understood
37
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Radiation effects
38Distance from IP1 (cw) [m]
Beam Losses
Courtesy S. Danzeca
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Not only ATLAS and CMS
39
ALICE ~13.5 nb-1
LHCb ~1.9 fb-1
Both profit from the long fills
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Luminosity lifetime 2016
40
Courtesy F.Antoniou, G. Iadarola, Y.Papaphilippou
ATLA
SC
MS
6h turnaround
72b 3.0μm 185μrad96b 2.5μm 185μrad96b 2.5μm 140μrad
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Losses in collisions• During the first few hours
in collisions losses well in excess of the burn-off
• After ~3h losses become dominated by luminosity burn-off
• Situation improved during the year (BCMS)
• Reduction of crossing angle has no effect
41
Courtesy F.Antoniou, G. Iadarola, Y.Papaphilippou
May October 140 μrad