Status and Outlook of the LHC

Enrico Bravin - CERN BE-BI

SPring-8 visit seminar26 June 2017

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

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

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

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

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Run 2Run 1

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

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

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

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

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

Combined Ramp & Squeeze

12

CR&S Squeeze

11m

2016 3m 2017 1m

40cm

10m

ATLAS & CMS

LHCb

ALICE

Beta

* [dm

]

6m

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)

13

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

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

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)

16

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

e-cloud in 2017 “Scrubbing” run

18

Sector 1-2 back where it was in 2016

19

Friday Sunday

Availability

20Courtesy B. Todd

6 June → 18 September Excellent availability!

Almost 50% of fills dumped by OP

Fault analysis

21Courtesy B. Todd

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

Standard vs BCMS beams in the PS

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Standard 72b batch εxy~2.5μmIbunch < 1.3E11

BCMS 48b batch εxy~1.5μmIbunch < 1.3E11

Beam structure

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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

LHC performance 2016

25

From end of June LHC operated consistently above design peak luminosity

Steady production from beginning of June

260 MJ/beam

Production 2016

26

Astonishing integrated luminosity achievement

Fast ramp-up after each configuration change Steady peace through the year

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!

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

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LHC as tide and earth quake monitor

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• 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

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

2016 2017

~ Same days of p-p physics

Status of 2017 run

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Long term LHC plan

34

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

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The End

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

Radiation effects

38Distance from IP1 (cw) [m]

Beam Losses

Courtesy S. Danzeca

Not only ATLAS and CMS

39

ALICE ~13.5 nb-1

LHCb ~1.9 fb-1

Both profit from the long fills

Luminosity lifetime 2016

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Courtesy F.Antoniou, G. Iadarola, Y.Papaphilippou

ATLA

SC

MS

6h turnaround

72b 3.0μm 185μrad96b 2.5μm 185μrad96b 2.5μm 140μrad

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