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The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.

Report from ‘ECFA High Luminosity LHC Experiments Workshop’ and the ‘Review of the LHC and Injector complex Upgrade Plans’ [RLIUP]

Markus zerlauth

Workshop Websites:• ECFA High Luminosity LHC Experiments:

• 1.-3. October in Aix Les Bain

• Review of the LHC and Injector Upgrade Plans:

• 29.-31. October in Archamps together with the C-MAC

23rd Joint HiLumi LHC-LARP Annual Meeting, Daresbury 11-15 November 2013

Oliver Brüning CERN

https://indico.cern.ch/conferenceDisplay.py?confId=260492

http://indico.cern.ch/conferenceOtherViews.py?view=standard&confId=252045




http://indico.cern.ch/conferenceOtherViews.py?view=standard&confId=252045

Motivation:• Review the performance potential and expectations based

on the operational experience with the LHC RunI.

• Need for Coordinating the various upgrade plans (ATLAS, CMS, LHCb, ALICE, LHC machine and injector complex).

• Review the shutdown and operation plans before HL-LHC project start to maximize the LHC physics potential before HL-LHC (e.g. LINAC4 connection, ATLAS and CMS upgrade plans versus LHCb and ALICE and required LHC and injector consolidation prior to HL-LHC)



Discussion Topics:• Performance summary of RunI• Questions, assumptions and comments for upgrade planning• Current Baseline schedule• HL-LHC Performance Expectations

Need to review future upgrade plans in view of RunI experience-how quickly can – will we reach hardware limits after LS1

[cryo limit of triplets, pile-up limit of detectors])-how much integrated luminosity can one hope for in RunII

• Shutdown Requirements What is required for LS2? And prior to LS3? When can we connect LINAC4? Need to review running scenarios and configurations in view of LHC RunI experience

• Case studies for RLIUP workshop:PIC (1ab-1), Upgrade Scenario 1 (2ab-1), Upgrade Scenario 2 (3ab-1) = Full HL-LHC



2010: 0.04 fb-1

7 TeV CoM Commissioning

2011: 6.1 fb-1

7 TeV CoM Exploring the limits

2012: 23.3 fb-1

8 TeV CoM Production

Performance Summary of RunI:



2012 Performance: 77% of design luminosity - @ 4/7 design energy - >> nominal bunch intensity- ~70% nominal emittance- b* = 0.6 m (design 0.55 m) @ 4 TeV- 50ns half nominal number of bunches and

twice the nominal pile-up!


Huge efforts over last months to prepare for high lumi and pile-up expected in 2012: optimized trigger and offline algorithms (tracking, calo noise treatment, physics

objects) mitigate impact of pile-up on CPU, rates, efficiency, identification, resolution in spite of x2 larger CPU/event and event size we do not request additional

computing resources (optimized computing model, increased fraction of fast simulation, etc.)

Z μμ

Z μμ event from 2012 data with 25 reconstructed vertices

2012: ~30 events/xing at beginning of fill

with tails up to ~ 40.

2011: average 12 events/xing,

with tails up to ~20

Performance Summary of RunI:

h = 9 h = 21

h = 9 10 1112 13 14 7 21

h =

21

42

8

4

+4 bunches

4 bunches

Nominal: Double batch injection (4+2 bunches)

into PS→ triple and two double splitting of 4

+ 2 bunches 6 * 12 = 72 bunches per PS cycle.

Batch Compression Merging Splitting Scheme: Double batch injection (4+4 bunches)

into PS→ bunch merging; triple and two double

splittings 4 * 12 = 48 bunches per PS cycle.

Bunch spacing[ns]

Protons per bunch [ppb]

Norm. emittance H&V [mm]

Exit SPS

25 (design report) 1.15 x 1011 3.7525 1.2 x 1011 2.750 1.7 x 1011 1.8

Huge performance potential for high brightness beams generation in the injector complex!!!

50ns operation in RunI has shown that these high brightness beams can be brought into collision in the

LHC!



Assumptions for HL-LHC Collision Parameters:• 5% intensity loss assumed during the cycle from SPS extraction to LHC collisions

Average lifetime along the cycle before collision of ~22 hours But minimum lifetime > 0.2 hours (assuming tight collimator settings) limited by power

deposited on the collimators

• Emittance blow-up of 20% from SPS extraction to LHC collision when compatible with inevitable sources of blow-up IBS• Margin of ~10-15 % on the average emittance blow-up on top of IBS• IBS calculations including injection/ramp and squeeze assuming controlled-longitudinal

blow-up to keep bunch length at 10 cm up to flat-topSPS Extraction LHC collision

(min. value – IBS) LHC collision

Bunch population[1011]

en (H/V)[mm]

en (H/V)[mm]

Bunch population[1011]

en coll (H/V)[mm]

Blow-up[%]

BCMS 1.45 1.45/1.45 1.74/1.45 1.38 1.85/1.85 27

Standard 1.45 1.85/1.85 2.09/1.85 1.38 2.25/2.25 21

[G. Arduini comparing performance with PIC & LLRF SPS upgrade @ RLIUP workshop]83rd Joint HiLumi LHC-LARP Annual Meeting, Daresbury 11-15 November

2013Oliver Brüning CERN

General Considerations & Questions:• LHC machine:

• How long can the machine run without TS? (Cryogenics, maintenance…)• Review of Performance potential based on RunI experience

• Injectors:• Linac4 connection, timing and staging of LIU upgrades• Risks of running with Linac2 until 2018/2019

• Experiments:• Coordinating and planning for ALL Upgrades: LS2 & LS3, EYETS?• Detector performance:

Pileup and pileup density limitations [140 and 0.6/mm to 1.3/mm for HL-LHC] Luminosity leveling between all experiments (5 orders of magnitude)

• Longer-term strategy:• Accelerator technology development time• Detector technology development time, funding profiles for the upgrades…• Radiation issues and personnel protection during installation work 93rd Joint HiLumi LHC-LARP Annual Meeting, Daresbury 11-15 November

2013Oliver Brüning CERN

Extended Year End Technical Stop (EYETS):• CMS:

• 4 layer pixel ready to install at end of 2016 [all preparations, including new beam pipe and cooling system installed in LS1.]

• 4.5 months beam to beam (plus some contingency)

• Other experiments

• ATLAS don’t need it

• Not of any significant benefit to ALICE and LHCb but…

• Cryogenics

• magnets would be kept cold below 80K during this "physics break”

• could imagine some training quenches in order to push towards 7 TeV.

• some opportunity for selective maintenance

• LIU preparation

• Could use time in Booster/PS – e.g. cable cleanup



[Mike Lamont @ RLIUP]

Baseline Schedule: Standard Operation Year

Phase Days

Christmas technical stop including HWC – beam to beam 91 (13 weeks)

Commissioning with beam (double coming out of a LS) 21

Machine development 22

Scrubbing 7 (to 14)

Technical stops 15 (3 x 1 week)

Technical stop recovery 6

Proton physics including intensity ramp-up 160

Ion run set-up 4

Ion physics run 24

Contingency 7 (or 0)

Total 365





Baseline schedule and Performance:



Splice Consolidation & Energy Increase

LIU (PSB, L4 and SPS), collimation and

Experiment upgrades

HL-LHC Installation

Reference Schedule after LS3:



[Malika Meddahi @ Preparation of RLIUP]

Main points from ECFA workshop:• Request for a minimum goal of 3000 fb-1

• The HL-LHC is a Higgs factory (measure self-coupling at the 10% level)• Major upgrades for LHCb and ALICE planed in LS2 • New concept of Pileup density limit and luminous region control for the

General Purpose experiments! HL-LHC performance limit!?!• Interest - no complaint - if LS2 gets delayed by one year• TAS and TAN upgrades required for HL-LHC interplay with experimental

beam pipes

• LS2 should last 18 month• LS3 should last 2-3 years • Ion operation is a vital part of the HL-LHC program• Wishes for special operation modes before HL-LHC:

e.g. Proton-Proton operation at lower center-of-mass energy



LS2 Requests from Experiments:• ALICE

• Major upgrade of ALICE detector, for installation in 2018/19• “we assume LS2 is 18 months”• “would not violently object if LS2 shifts to 2019” – would provide important

contingency

• LHCb• Requires 18 months• A later start of LS2 at end 2018 would be advantageous for LHCb • Further delay of the start of LS2 beyond 2018 would be disfavoured

• ATLAS• Assumes baseline (LS2 14 months and starting in 2018)

• CMS• LS2: Assumes 14 to 18 months• Prefers LS2 starting end 2018 preparatory work for LS3 (e.g. TAS) [Worry

about radiation levels forcing potential constraints/cool-down time etc. ] &• “to collect sufficient data… LS2 must not start before summer 2018”




Case Studies for RLIUP:

• Performance Improving Consolidation (PIC) only

can one reach 1000fb-1 with 10 years of operation?

• Upgrade Scenario 1 (PIC plus selected upgrade options)

can one reach 2000fb-1 with 10 years of operation?

• Upgrade Scenario 2 (PIC plus all upgrade options)

can one reach more than 3000fb-1 with 10 years of operation?



Main points from RLIUP:• Very high brightness performance in LHC limited by IBS.• Experiments are NOT interested in an extended EYEST [>

9 month] with LINAC4 connection between LS1 and LS2.• Concept of Pileup density limitation and luminous region

control is a key ingredient defining the running scenarios and optimum upgrade options for the General Purpose experiments in HL-LHC.

• Experiments would not complain if LS2 delays by 1 year• LS2 should last 18 month• LS3 should last 2-3 years



Main points from RLIUP:• US1 (2000fb-1) can be reached with full LIU upgrade +

PIC (new triplet and collimation upgrade) in the LHC!• Upgrade costs are small compared to LHC operation

cost upgrade for maximum performance as fast as possible!

• US2 goal is challenging with pile-up density limit!• Machine reliability is critical for success of HL-LHC!• Remote handling requirements for TS after LS3!• New RF options: 200 MHz, 800MHz (for IBS, Crab Kissing

scheme, e-cloud, and luminous region control)• New e-cloud backup scheme: 8b4e with 25ns



Challenge of Reaching US2 Goals:

[RLIUP Session 2 Summary by Gianluigi Arduini]

An exponential fill length distribution is used for the performance figures quoted in the next slides.

2011 2012

Fill lengths in 2011 and 2012 exponentials.o ~30% of the fills are dumped by OP.

J. Wenninger



• HL experiments accept 140 events/crossing, with 1.3 mm-1 density

(performance limit with impact

on efficiency)

• Long fills (>6 h) and high

pile-up (>140) are key

ingredients for US2

integrated luminosity target.

• Main challenges besides e-cloud: effective leveling method and good reliability.

[R. De Maria]

US2

Challenge of Reaching US2 Goals:



LS2 Requests from Injectors:Approx.months

Linac4 Linac4 connection to the PSB takes place during LS2

PSB Total of 16 months for PSB works including 1.5 months of cool-down and 4 months of beam commissioning Cabling activity in the PSB defines the critical path!

17.5

PS PS upgrade is determined mainly by magnet program (replacement of the PFWs) – about 1 year – plus 1 month cool-down

17.5 + 1

SPS 12 months for the 200 MHz upgrade 12 months for aC coating of main bending magnets (tbc)Injection upgrade

18.5 + 2

Full Injector Upgrade

20.5topilot

Some co-commissioning injectors/LHC might be necessary



Experiments Perspective for Ions: • Pb-Pb Performance wishes:

• 3nbarn-1 by LS3 in ATLAS. All experiments like to collect at least 1nbarn-1 during RunII.• 10nbarn-1 for ALICE after upgrade during LS2.• LHCb: p-Pb NOT at the end of ion program of RunII compatibility with ALICE plan?• ALICE requires leveling during Pb-Pb and p-Pb (while ATLAS and CMS do not)

Physics and Machine coordination!!!• The Pb-Pb runs in 2015 and 2016 can NOT be grouped (trigger configurations) No to

an extended ion run as part of LS1.5 and the LINAC4 connection!• LHCb would like 10 times more integrated luminosity with p-Pb as compared to Run1.• ALICE polarity reversals on regular basis.

• Performance wishes after LS2:• Different beam species: Pb-Pb, p-Pb, Ar-Ar, p-Ar• 10 fold increase in beam performance expected from ALICE collimation upgrade and

vacuum conditions? Requires SPS and LINAC3 upgrades and increase in LEIR intensity!



Ion beam Performance and machine upgrade plans:• Performance summary of RunI:

• 2 bunches, 200ns spacing in PS 24 bunches in SPS 360 bunches in LHC

• Upgrade Plans:• Increasing the bunch intensity is not a viable option (IBS and luminosity burn off)• 100ns batch compression in the SPS (already envisaged for RunII in the PS but

without the SPS injection upgrade 432 bunches for RunII).• Increasing the number of injections would increase the injection time and thus the

emittance growth keep the number of PS injections into the SPS at 12 requires SPS injection system upgrade (recuperated equipment from PSB energy upgrade, not requiring new kicker magnets) 624 bunches in the LHC @ collision

• Requires higher bunch intensities in LEIR (already above design and currently limited) further studies required

• Slip stacking in the SPS to be re-evaluated smaller bunch spacing (e.g. 50ns?)• LINAC3 pulsing @ 10Hz (source already pulsing @ 10Hz)• Wish for a dedicated source test stand for future source developments



Main points from RLIUP:• Recommendation for full LIU upgrade including PSB 2 GeV

Energy upgrade required for margins and confidence to produce US1 and US2 parameters!

• With all upgrade ingredients endorsed, one needs a resource loaded schedule to identify what upgrades can actually be implemented during which shutdown

• Recommendation for full HL-LHC upgrade with development of novel schemes that can alleviate limitations (pile-up density and e-cloud) and-or improve performance: New SC RF (200MHz, 800MHz, Crab Cavities); LRBB wire; Stochastic Cooling

• Recommendation to evaluate means for maximizing the machine availability during HL-LHC



25

HL-LHC goal could be reached by end 2035

L. Rossi @Kick-off Meeting 11 Nov 2013

M. Lamont, 7th HL-LHC Coordination Group, Jul.2013

Slipped baseline+12 Schedule: Mike Lamont @ RLIUP



HL start in 2025; HL goal could be reached by end 2037

Backup Transparencies:• -e-cloud and 8b4e backup

• -scrubbing fills



Operation Cycle:

LHC Operation Cycle @ 7Tev:

Matteo Solfaroli@ Evian 2012

70min 50min 31min

26minSqueeze

Total Minimum Turnaround Time:176min or 3 hours

Turnaround Time

HL-LHC Performance Estimates

Parameter nominal 25ns 50ns

N 1.15E+11 2.2E+11 3.5E+11nb 2808 2808 1404beam current [A] 0.58 1.12 0.89

x-ing angle [mrad] 300 590 590

beam separation [s] 10 12.5 11.4b* [m] 0.55 0.15 0.15en [mm] 3.75 2.5 3.0eL [eVs] 2.51 2.5 2.5

energy spread 1.20E-04 1.20E-04 1.20E-04

bunch length [m] 7.50E-02 7.50E-02 7.50E-02IBS horizontal [h] 80 -> 106 20.0 20.7IBS longitudinal [h] 61 -> 60 15.8 13.2Piwinski parameter 0.68 3.1 2.9geom. reduction 0.83 0.31 0.33beam-beam / IP 3.10E-03 3.9E-03 5.0E-03Peak Luminosity 1 1034 7.4 1034 8.5 1034

Virtual Luminosity 1.2 1034 21 1034 26 1034

(Leveled to 5 1034 cm-2 s-1

and 2.5 1034 cm-2 s-

1)

‘Stretched’ Baseline Parameters following 2nd HL-LHC-LIU:

6.2 1014 and 4.9 1014

p/beam

sufficient room for leveling (with Crab Cavities)

Virtual luminosity (25ns) ofL = 7.4 / 0.35 1034 cm-2 s-1

= 21 1034 cm-2 s-1 (‘k’ = 5)

Virtual luminosity (50ns) ofL = 8.5 / 0.33 1034 cm-2 s-1

= 26 1034 cm-2 s-1 (‘k’ = 10)



Max. luminosity in one fill 237 pb-1

Max. luminosity delivered in 7 days 1350 pb-1

Longest time in stable beams (2012) 22.8 hoursLongest time in stable beams for 7 days 91.8 hours (55%)

77% of design luminosity: - @ 4/7 design energy - >> nominal bunch intensity- ~70% nominal emittance- b* = 0.6 m (design 0.55 m) @ 4 TeV- 50ns half nominal number of bunches and

twice the nominal pile-up!Impressive performance after only 3 years of operation and at E = 4 TeV!

Peak Performance Summary:



32

E-cloud G. Rumolo, G. Iadarola

Arc dipole, 2808b, 1 beam Arc quadrupole, 2808b, 1 beam

SEY=1.4

SEY=1.3

US1, US2

PIC

E-cloud solution currently betting on:• Scrubbing for dipoles for suppression of electron cloud• Expected to be difficult to eliminate the electron cloud in the quadrupole• Effects on on beam only at injection (optimize injection duration)

29-31. October; Review of the LHC and Injector Upgrade Plans; Archamps


Available cooling *

[W]

MaxMeas3429[W]

Scaling factor (Nbun= 2700)

Scaling factor(E=7 TeV +

nominal filling)

US1, US2[W]

(SEY like 2012)

US1, US2[W]

(dipoles fully scrubbed)

Arc half-cell 255 45 x3.4 0.81x3.5(0.0) + 0.19x0.15

438(x 1.72)

4.4(x 0.02)

SAM 1 16 12 x3.4 x0.15 6.12(x 0.38)

6.12(x 0.38)

SAM 2 24 17 x3.4 x0.15 8.67(x 0.36)

8.67(x 0.36)

D3IP4 24 4 x3.4 x3.5(0.0) 47.6(x 1.98) –

Semi-SAM 40 18 x3.4 0.3x3.5(0.0) + 0.7x0.15

70.69(x 1.77)

6.43(x 0.16)

* From L. Tavian, Evian Workshop 2012If dipoles not fully scrubbed (but maybe just enough to cope with heat load), the higher intensity bunches of US1 and US2 could still suffer more from the interaction with the electron cloud

3329-31. October; Review of the LHC and Injector Upgrade Plans; Archamps

G. Rumolo





Baseline Schedule until LS3:

LS1

RUN 2

RUN 3

LS2

LS3




Reference Schedule before LS3:

Documents

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