giulia papotti

Giulia Papotti(BE-OP-LHC)

for the LHC team

127th LHCC MeetingCERN, 21 September 2016

thanks in particular to M. Lamont and J. Wenninger

additionally, with material from:

S. Danzeca, M. Hostettler, G. Iadarola, J. Jowett, C. Schwick, M. Solfaroli, J. Wenninger

outline

• 2016 performance

• some details on selected subjects• electron cloud, Unidentified Falling Objects, Radiation to

Electronics

• latest news, schedule and outlook

2016.09.21 [email protected]

peak luminosity


2016 2015 Design Report

energy [TeV] 6.5 6.5 7

bunch spacing [ns] 25 25 25

b* [cm] 40 80 55

eN[mm mrad] at start of fill 2 3.5 3.75

Nb, bunch population [1011 p/bunch] 1.12 1.15 1.15

k, max. number of bunches 2220 2240 2808

max. stored energy [MJ] 260 270 360

peak luminosity [1034 cm-2s-1] in IP1/5 ~1.25 ~0.5 1

pile-up 41 18 20

2016 performance so far

• cf target for 2016: 25 fb-1

• max. luminosity delivered in

7 days: 3.3 fb-1 (ATLAS)- Mon 29 Aug – Sun 4 Sep


Peak

Luminosity[cm-2s-1]

Integrated

Luminosity[fb-1]

ATLAS 1.21 1034 29.3

CMS 1.33 1034 30.5

put in perspective


physics efficiency

• improved operational efficiency - combine ramp and squeeze

- shorten precycle

- minimum turn around <3 h

• amazing system availability!- cf ~33-35% in stable beams of

the previous years


65% 20%

15%

FAULTS

STABLE

BEAMS

OPERATION

mid-year availability,

physics production only

(no commissioning, MD, …)

• good luminosity lifetime- optimize fill length and dump time

beam parameters

• number of bunches per injection limited to 96 by SPS dump- max 2220 bunches/ring

• intensity per bunch limited to 1.1e11 ppb- outgassing from ceramic connection in

LHC injection kicker

• smaller emittance and high brightness from BCMS beams- Batch Compression, Merging and Splitting

- 2 um into collision, cf 3.75 um nominal


BMCSstandard

limitations

• SPS beam dump: replace during EYETS

• injection kicker: add pumping during EYETS

• potential inter-turn short in sector 12- being monitored

- lowered Beam Loss Monitor thresholds to play it safe

- to be replaced during the EYETS

• electron-cloud

• Unidentified Falling Objects

• Radiation to Electronics (R2E)


electron cloud• SEY>threshold: avalanche effect (multipacting)

- effect depends on bunch spacing and population

- SEY decreases with accumulated dose: “scrubbing”

• e-cloud effects observed in LHC with bunch trains- vacuum pressure rise, heat load on cryogenic systems

- beam size growth, single- and multi-bunch instabilities

• anticipated & confirmed to be a challenge with 25 ns- 2015: lived at the heat-load limit

• 2016: still significant heat-load within cryogenic limits- scrub with physics asap (almost no dedicated scrubbing at the flat bottom)

- dynamics well handled by cryogenics feed-forward, no impact on operations


Secondary

Emission

Yield

little improvement

over the year

Unidentified Falling Objects (UFOs)

• fast loss events (ms timescale) due to dust particles falling into the beam- feared for availability at high energy operation: less margin for magnets, more losses per event

• 2016 so far: 13 dumps + 3 beam-induced quenches- loss monitor thresholds increased to allow few quenches per year

• most beam dumps would not have quenched

• conditioning with beam time confirmed- very high rates observed at start 2015, now settled at ~2 arc UFOs/hour in stable beams

- deconditioning did not take place after year end stop


2015 2016

Radiation to Electronics (R2E)

• failure rates proportional to radiation levels- IP: rad level mainly from integrated luminosity

- arc: rad level mainly from beam-gas interaction, thus integrated intensity

• 2016: 3 radiation-related dumps up to 20 fb-1 (expected ~1 dump/fb-1)- arc radiation levels per unit luminosity are lower than in 2015

• can be due to the lower vacuum pressure in the arc, or to the higher luminosity per proton (smaller beta*), analysis ongoing

• very clean machine, luminosity losses are burn-off dominated, less e-cloud


0

0

1

10

DCUM

16L5 16R5IR5

loss ratio

2016 vs 2015

per fb-1

(over 20 fb-1)

IP: ratio is 1

arc: ratio is 0.3

incoming: 2016

• ongoing this week:- 2.5 km beta* run

- crossing angle reduction for low beta* proton physics

• next:- 9 days of machine developments

- dense ion run: p-Pb at 5 TeV, p-Pb and Pb-p at 8 TeV,

- 2 weeks of dipole training towards 7 TeV equivalent• before Extended Year End Technical Stop (EYETS)


ML

V2.0

Jan Feb Mar

Wk 1 2 3 4 5 6 7 8 9 10 11 12 13

Mo 4 11 18 25 1 8 15 22 29 7 14 21 28

Tu

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Apr May June

Wk 14 15 16 17 18 19 20 21 22 23 24 25 26

Mo 4 11 18 25 2 9 16 23 30 6 13 20 27

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July Aug Sep

Wk 27 28 29 30 31 32 33 34 35 36 37 38 39

Mo 4 11 18 25 1 8 15 22 29 5 12 19 26

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Oct Nov Dec

Wk 40 41 42 43 44 45 46 47 48 49 50 51 52

Mo 3 10 17 24 31 7 14 21 28 5 12 19 26

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Technical Stop Machine development

Recommissoning with beam Special physics runs

Scrubbing

September 1, 2016

LHC Schedule 2016Approved by the Research Board, December 2015

Year end technical stop

Xmas

MD 2

TS1

End of LHC run[06:00]

Extended year end technical stop

MD 4

MD 5

Ion run(p-Pb)

TS2

Ionssetup

Recommissioningwith beam

TS3

1st May

Ascension

Easter Mon

Whit

Jeune G

New Year

MD 1

Powering tests

Lab closed

May Day comp

be

ta

* =

2.5

km

da

ta

ta

kin

g

VdM

DSO test

beta* 2.5 kmdev.

beta* 2.5 kmdev.

Ma

ch

ine

ch

ecko

ut

G. Friday

Injector TS(8 hours)

Scrubbing

Pb MD

VdM

MD 3

beta* 2.5 kmdev.

ML

V2.0

Jan Feb Mar

Wk 1 2 3 4 5 6 7 8 9 10 11 12 13

Mo 4 11 18 25 1 8 15 22 29 7 14 21 28

Tu

We

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Fr

Sa

Su

Apr May June

Wk 14 15 16 17 18 19 20 21 22 23 24 25 26

Mo 4 11 18 25 2 9 16 23 30 6 13 20 27

Tu

We

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July Aug Sep

Wk 27 28 29 30 31 32 33 34 35 36 37 38 39

Mo 4 11 18 25 1 8 15 22 29 5 12 19 26

Tu

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Oct Nov Dec

Wk 40 41 42 43 44 45 46 47 48 49 50 51 52

Mo 3 10 17 24 31 7 14 21 28 5 12 19 26

Tu

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Scrubbing

September 1, 2016



Xmas

MD 2

TS1



MD 4

MD 5

Ion run(p-Pb)

TS2

Ionssetup


TS3

1st May

Ascension

Easter Mon

Whit

Jeune G

New Year

MD 1

Powering tests

Lab closed

May Day comp

be

ta

* =

2.5

km

da

ta

ta

kin

g

VdM

DSO test

beta* 2.5 kmdev.

beta* 2.5 kmdev.

Ma

ch

ine

ch

ecko

ut

G. Friday


Scrubbing

Pb MD

VdM

MD 3

beta* 2.5 kmdev.

ML

V2.0

Jan Feb Mar

Wk 1 2 3 4 5 6 7 8 9 10 11 12 13

Mo 4 11 18 25 1 8 15 22 29 7 14 21 28

Tu

We

Th

Fr

Sa

Su

Apr May June

Wk 14 15 16 17 18 19 20 21 22 23 24 25 26

Mo 4 11 18 25 2 9 16 23 30 6 13 20 27

Tu

We

Th

Fr

Sa

Su

July Aug Sep

Wk 27 28 29 30 31 32 33 34 35 36 37 38 39

Mo 4 11 18 25 1 8 15 22 29 5 12 19 26

Tu

We

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Su

Oct Nov Dec

Wk 40 41 42 43 44 45 46 47 48 49 50 51 52

Mo 3 10 17 24 31 7 14 21 28 5 12 19 26

Tu

We

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Sa

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Scrubbing

September 1, 2016



Xmas

MD 2

TS1



MD 4

MD 5

Ion run(p-Pb)

TS2

Ionssetup


TS3

1st May

Ascension

Easter Mon

Whit

Jeune G

New Year

MD 1

Powering tests

Lab closed

May Day comp

be

ta

* =

2.5

km

da

ta

ta

kin

g

VdM

DSO test

beta* 2.5 kmdev.

beta* 2.5 kmdev.

Ma

ch

ine

ch

ecko

ut

G. Friday


Scrubbing

Pb MD

VdM

MD 3

beta* 2.5 kmdev.

ML

V2.0

Jan Feb Mar

Wk 1 2 3 4 5 6 7 8 9 10 11 12 13

Mo 4 11 18 25 1 8 15 22 29 7 14 21 28

Tu

We

Th

Fr

Sa

Su

Apr May June

Wk 14 15 16 17 18 19 20 21 22 23 24 25 26

Mo 4 11 18 25 2 9 16 23 30 6 13 20 27

Tu

We

Th

Fr

Sa

Su

July Aug Sep

Wk 27 28 29 30 31 32 33 34 35 36 37 38 39

Mo 4 11 18 25 1 8 15 22 29 5 12 19 26

Tu

We

Th

Fr

Sa

Su

Oct Nov Dec

Wk 40 41 42 43 44 45 46 47 48 49 50 51 52

Mo 3 10 17 24 31 7 14 21 28 5 12 19 26

Tu

We

Th

Fr

Sa

Su



Scrubbing

September 1, 2016



Xmas

MD 2

TS1



MD 4

MD 5

Ion run(p-Pb)

TS2

Ionssetup


TS3

1st May

Ascension

Easter Mon

Whit

Jeune G

New Year

MD 1

Powering tests

Lab closed

May Day comp

be

ta

* =

2.5

km

da

ta

ta

kin

g

VdM

DSO test

beta* 2.5 kmdev.

beta* 2.5 kmdev.

Ma

ch

ine

ch

ecko

ut

G. Friday


Scrubbing

Pb MD

VdM

MD 3

beta* 2.5 kmdev.

year end technical stop

powering tests

machine checkout

re-commission

with beam

full-on

physics production

includes

machine developments

ion run

powering tests

year end technical stop

today

crossing angle reduction

• crossing angle required because of bunch trains- otherwise parasitic collisions not in the center of the detector

- negative impact on luminosity… keep it as small as possible

• constraint: minimum beam separation- big beam emittance or small beta* require bigger crossing angle

• BCMS beams are smaller than standard- machine setup for standard, now reduce crossing angle

- plan it well: validation overhead not to dominate!


f [mrad] 370 280

F 0.59 0.70

Lpk [1034cm-2s-1] 1.27 1.5

Run 2 schedule

• Extended Year End Technical Stop (20 weeks)- driven by CMS pixel upgrade

- push 2 sectors towards 7 TeV, to gain knowledge on how long it takes to reach higher energy

• ~40-45 fb-1/year in 2017 and 2018 (goals fixed at Chamonix 2017) - max peak luminosity ~1.7e34 cm-2s-1, limited by inner triplets


today

projections until LS2

• BCMS or not?- BCMS: low emittance, thus low crossing angle: higher luminosity/bunch pair

• TDI limits on number of bunches/SPS transfer: less bunches/ring

• less electron-cloud thanks to the shorter trains

- standard beams: +30% bunches, but higher emittance: likely less luminosity• less pile-up

- choice requires input from experiments

• if pile-up is an issue, level down

• need to start the year with the correct parameter set!- commissioning and validation are non-negligible overhead

• availability is the key to good integrated luminosity!- max peak luminosity is limited

- 2016, 2017, 2018: similar run length


machine developments• reserve ~10% of beam time per year

• invest it in short & long term performance improvements

• examples in 2016:- luminosity performance: beta* reach, reduced crossing angle, luminosity levelling options

- HL-LHC optics (ATS) for possible deployment in Run 2

- collective effects & instability limits

- hardware performance (collimators, RF, ...)

- many many others!


160 140 120 100 185 100 185

10%

CMS

ALICE

½ xing angle in mrad

ex 1: leveling by crossing angle

ex 2: leveling by separation

time [h]

lum

ino

sity [H

z/u

b]

conclusions

• excellent peak performance- above design luminosity (squeeze further, bright beams from injectors)

- still some margin for improvement in Run 2

• good delivery of integrated luminosity- stunning availability

- good luminosity lifetime

- electron cloud conditioning very slowly

- fortunately UFOs have conditioned down

• the LHC has moved from commissioning to exploitation- enjoying the benefits of the decades long international design,

construction, installation effort: the foundations are good

- huge amount of experience & understanding gained and fed-forward

• astounding results and progress represent a phenomenal ongoing effort by all the teams involved


the Large Hadron Collider

Lake of Geneva

CMS

Pt4: RF & BI

SPS


ATLASLHCb

ALICE

Pt7: collimators

Pt3: collimators

Pt6: dump

Pt8: inj b2

Pt2: inj b1

LHC operation history


2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

firststart-up

Long Shutdown 1

Long Shutdown 2

first experience(3.5 TeV)

probing the limits

production(4 TeV, 50 ns beams)

first experience(6.5 TeV, 25 ns beams)

production

production

production

2015 goalestablish p+p+ collision

at 13 TeV CoMwith 25 ns and low b*:

(prepare production in 2016)

luminosity lifetime

• emittance- small horizontal growth, vertical shrinkage

(MOPMR025)• enjoy benefits of synchrotron radiation,

small IBS (TUPMW002)

• some additional blow up

- longitudinal shrinkage• get to the limit of stability in long fills

• good transmission- ~2% losses from start of acceleration to

physics

• in physics, mainly losses from burn-off

• healthy luminosity lifetime- 30-60 hours

- long fills are preferred (>20 hours)


courtesy of M. Hostettler

courtesy of J. Muller

hardware performance at 6.5 TeV

• dipole quenches- slow training of main dipoles to 6.5 TeV

• had 175 quenches, while expected ~100

- only 5 training quenches during beam operation

- possible test of 7 TeV before Long Shutdown 2

• magnets behave well at 6.5 TeV

• excellent magnetic reproducibility- allow control and feedforward of tune and

chroma


• cryogenic system handling electron-cloud driven heat-load transients- new algorithm, first 2016 test look excellent

beta*11m 0.8m

courtesy of

A. Gorzawski

machine studies: beta* levelling

• 10% of time with beam invested in machine studies

• pick one highlight among many- TUPMW013: beta* leveling, and collide + squeeze fully demonstrated

• see the beta* go down and lumi increase smoothly, over 12 minutes


25Matteo Solfaroli, Weihai – 14th Aug 2016

A few problems

turnaround

• finally starting clipping fill length!


giulia papotti

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