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Status of LHC Performance

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Status of LHC Performance. P erformance, problems, projection. Mike Lamont for the LHC team. Ramp-up of number of bunches. MD, technical stop. Intermediate energy, TS, scrubbing. 15 weeks. Ramp-up - p erformance. Reached 1380 ( maximum possible with 50 ns bunch spacing) on 27 th June. - PowerPoint PPT Presentation
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Status of LHC Performance Mike Lamont for the LHC team Performance, problems, projection
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Page 1: Status of  LHC Performance

Status of LHC Performance

Mike Lamont for the LHC team

Performance, problems, projection

Page 2: Status of  LHC Performance

Ramp-up of number of bunches

22-8-2011

Intermediate energy, TS, scrubbing

MD, technical stop

15 weeksLHC status

Page 3: Status of  LHC Performance

LHC status 3

Ramp-up - performance

2-8-2011

Reached 1380 (maximum possible with 50 ns bunch spacing) on 27th June

Page 4: Status of  LHC Performance

Luminosity

LHC status2-8-2011 4

26 pb-1/day

Page 5: Status of  LHC Performance

LHCb

LHC status 52-8-2011

Page 6: Status of  LHC Performance

UFOs In particular at the injection kickers

Single Event Effects (SEE) QPS, Cryogenics, Collimators, Power converters…

RF Couplers – particularly on trips RF wave-guide arc detectors

Beam induced heating injection kickers, cryogenics, collimators..

Vacuum activity

Ramp-up: not all plain sailing

2-8-2011 6LHC status

From 3 to 1380 bunches with a previous maximum of 368 in 15 weeks elapsed (via MD, TS, scrubbing, intermediate energy) has to be regarded as pretty good, however…

Page 7: Status of  LHC Performance

Collimation always critical Good stability - regular loss maps performed

144 bunches from SPS Beam quality from injector important 144 bunches per injection from SPS - 1.2 MJ down the lines

High temperature superconducting current lead quenched (7th April) Invoked quench of 11 magnets

Injection Kicker Flashover (18th April) Not pretty, heavy beam loss

Injection kicker erratics (28th July) Two incidents – not pretty, heavy beam loss

Increasing intensity – machine protection

2-8-2011 7LHC status

Routinely dealing with 90 to 100 MJ per beam at 3.5 TeV

Page 8: Status of  LHC Performance

2011 parameters - end June

LHC status

Energy [TeV] 3.5

Beta* [m] 1.5, 10, 1.5, 3.0 m

Normalized emittance [microns] 2.5 – 3.1 start of fill

Bunch intensity 1.1 - 1.2e11

Number of bunches 13801318 collisions/IP1&5

Bunch spacing [ns] 50 – good choice

Stored energy [MJ] 90 to 100

Peak luminosity [cm-2s-1] 1.27e33

Beam-beam tune shift ~0.015 – 0.017

82-8-2011

Page 9: Status of  LHC Performance

LHC status 92-8-2011

Emittance

• As we move around the machine the shape of the ellipse will change as (s) changes with the varying quadrupole (de-)focusing

• However the area of the ellipse () does not change

• Emittance shrinks naturally as we go up in energy (pS increases, pT doesn’t)

• Define energy independent normalized emittance:

• Units are mm.mrad but normally use microns (and drop normalized)

• Handy – constant across complex (give or take some blow-up)

x’

x

x

Page 10: Status of  LHC Performance

Aim: maximize peak luminosity

LHC status 102-8-2011

N Number of particles per bunch

KbNumber of bunches

f Revolution frequency

Beam size at interaction point

F Reduction factor due to crossing angle

Emittance

Normalized emittance

Beta function at IP

Page 11: Status of  LHC Performance

Minimize (normalized) emittance (~2 microns) Adiabatically increase bunch intensity (to ~1.6e11 ppb)

Maximum from injectors with 50 ns Beta* = 1 m should be OK (collimation, beam-beam)

Prepare test and then possibly implement after next technical stop

Stick with 50 ns Test 25 ns in MD & trial stable beams with limited number of 25

ns trains

Conclusions from mini-Chamonix

2-8-2011 11LHC status

before after buys

Emittance 2.5 – 3.0 2.0 ~1.38

Bunch intensity 1.2 1.6 ~1.78

Beta* 1.5 1 ~1.5

Page 12: Status of  LHC Performance

Emittances – start of fill – from luminosity

LHC status 122-8-2011

Page 13: Status of  LHC Performance

Bunch intensities

LHC status2-8-2011 13

Emittances down, bunch intensity more-or-less constant

Page 14: Status of  LHC Performance

It wasn’t meant to be like this

LHC status 142-8-2011

20% of design luminosity: - half design energy - nominal bunch intensity- half nominal emittance- beta* = 1.5 m (design 0.55 m)

Page 15: Status of  LHC Performance

Up until a week ago we’d been working with emittance blow-up in the SPS to give around 2.0 microns injected into the LHC (having worked down from 2.5 - 3.0) This gave good luminosity but some issues with beam losses

when adjusting collisions before stable beams

When switching off the blow-up completely – emittance from SPS of 1.6 microns – miraculously everything cleaned up Assumption: non-Gaussian tails generated by the blow-up were

causing the problem…

Emittance reduction

2-8-2011 15LHC status

Page 16: Status of  LHC Performance

Beam-beam tune shift

LHC status 162-8-2011

Tatiana Pieloni

Design report Now

Page 17: Status of  LHC Performance

Working point optimization

Fill 1992 – Qh = 0.312 Qv = 0.322

Coupled with the removal of transverse blow-up, removal of lifetime dip on going into collisions

Slight shift of the horizontal and vertical tune before collisions

Positive effect on beam lifetime either by moving some of the tune footprint away a resonance, or perhaps, a 50 Hz harmonic

Gianluigi Arduini2-8-2011 LHC status 17

Page 18: Status of  LHC Performance

OPERATIONAL EFFICIENCY

LHC status 182-8-2011

Page 19: Status of  LHC Performance

Last week: fills above 450 GeV 1/2

LHC status2-8-2011

Fill Mode Stable [h]

Int. L (pb-1)

Dump cause

Mon 25 1975 STABLE 2.5 13 Cryo valve PROFIBUS (UJ76) (SEU?)

Mon 25 1976 ADJUST - - Losses 83s RS on TCSG.A6L7.B1

Mon 25 1977 SQUEEZE - - RF Module trip

Mon 25 1979 STABLE 6 23 QPS RCO/RCD/RCS cross-talk S56

Tue 26 1980 RAMP - - False trip of 600A QPS RQTL7.R7B1.

Wed 27 1982 STABLE 2.5 13 Electrical network perturbation

Wed 27 1984 SQUEEZE - - Vacuum spike R2

Wed 27 1985 STABLE 11h22m 50.4 Electrical network perturbation

19

Page 20: Status of  LHC Performance

Last week: fills above 450 GeV 2/2

LHC status 202-8-2011

Fill Mode Stable [h]

Int. L (pb-1)

Dump cause

Thu 28 1986 STABLE 2.5 14 RF klystron vacuum

Thu 28 1990 STABLE 7.5 41 QPS trigger RCBXV3.R1 (SEU?)

Fri 29 1991 STABLE 5 27 Cryo valve PROFIBUS (UJ16) (SEU?)

Sat 30 1992 STABLE 56m 6.1 Collimator crate UJ16 (SEU?)

Sat 30 1993 STABLE 56m 6.4 UFO 31L8 on B1

Sun 31 1994 STABLE 45m 5.2 RF interlock on HOM line 2 B2

Sun 31 1995 ADJUST - - Mini UFO in triplet R1 from B1

Sun 31 1996 STABLE 1h9m 6.9 Lost cryo compressors in Pt8PLC problem

The last one took the cryogenics out for ~36 hours

Page 21: Status of  LHC Performance

Dumps > 450 GeV since Monday 18th July

LHC status 212-8-2011

From Monday 18th July and the move back up to 1380 bunches

Around 15/33 down to high intensity or high luminosity

Page 22: Status of  LHC Performance

Short fills hurt

LHC status 222-8-2011

and in particular LHCb

Page 23: Status of  LHC Performance

Still managed ~210 pb-1 last week

LHC status2-8-2011 23

Peak Stable Luminosity Delivered

2.03x1033 Fill 1993 11/07/30, 22:53

Maximum Luminosity Delivered in one day

63.7 pb-1 Friday 29 July, 2011

Maximum Luminosity Delivered in 7 days

276.15 pb-1 Saturday 23 July, 2011 - Friday 29 July, 2011

Page 24: Status of  LHC Performance

PROBLEMS PROBLEMS PROBLEMS

Three recent headaches

LHC status 242-8-2011

Page 25: Status of  LHC Performance

Luminosity driven SEE

LHC status 252-8-2011

Markus Brugger

Page 26: Status of  LHC Performance

LHC status 262-8-2011

Markus Brugger for R2E at mini-Chamonix

Page 27: Status of  LHC Performance

Planned mitigation – UJ16

LHC status 272-8-2011

Shield and re-locate

Christmas technical stopIn the meantime – victims of our own success

Page 28: Status of  LHC Performance

Vacuum - right of IP2 – last week

LHC status2-8-2011 28

Possible explanation (V. Baglin) is the outgassing of an ion pump when the discharge is starting from time to time. Increase the interlock

level on the nearby vacuum gauge temporarily to allow cleaning

Page 29: Status of  LHC Performance

Vacuum spikes 4L8: 23-24 July

LHC status2-8-2011

Dump Dump29

Page 30: Status of  LHC Performance

Triplets warmed up during technical stop to flush and pump absorbed gas

During the “distillation process”, most of the gas desorbed during the scrubbing run was either pumped out or flushed to the cold bore : Hydrogen, methane and carbon monoxide were pumped out Carbon dioxide was flushed to the cold bore Water remained at its original location

During this process, gas was redistributed in all the vacuum sector

So, we could expect some minor reconditioning ….

Vacuum after technical stop

2-8-2011 30LHC status

Vincent Baglin

And indeed the spikes do appear to have calmed down

Page 31: Status of  LHC Performance

Injection kicker erratics

LHC status 312-8-2011

D1

Side view

TDIKicker1. Un-kicked injected beam to

upper TDI jaw

2. Kicked circulating beam to lower jaw

Page 32: Status of  LHC Performance

Injection kicker – PFN & switches

LHC status 322-8-2011

PFN

DS MS

Mike Barnes

Page 33: Status of  LHC Performance

MKI2 Erratic of MS3 at 18:03:09hrs ON 28/7/2011

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000A

ppro

x PF

N V

olta

ge

Sample Number

MKI2. 28 July 2011, 6:03:09 PM

7/28/2011 6:03:09 PM PFN1

7/28/2011 6:03:09 PM PFN2

7/28/2011 6:03:09 PM PFN3

7/28/2011 6:03:09 PM PFN4

Erratic (untriggered) turn-on of MKI2 MS3

At 18:03:09hrs an erratic (untriggered) turn-on of MKI2 MS3 occurred during resonant charging – sending current to one of the four kicker magnets;

Interlocks did NOT detect erratic of MS3 (at 33kV): hence no immediate action was taken to turn-on other thyratrons. PFNs discharged via the DS after 4ms (no further magnet current);

The failure occurred early in the charging process, and the extraction from the SPS was inhibited;

The circulating beam which was swept over the aperture and protection elements (~17% of normal kick) for ~9µs.

PFNs 1 & 2 at normal voltage (~50kV)

PFNs 4 at low voltage (~33kV) because of PFN3 switch erratic

Mike Barnes

2-8-2011 LHC status 33

Page 34: Status of  LHC Performance

MKI2 event no. 2 – dumped beam BTVDD and dump line BCTs indicate that ~ 200 bunches

of the circulating were not dumped to TDI.

2-8-2011 LHC status 34

Page 35: Status of  LHC Performance

NEXT THREE MONTHS

LHC status 352-8-2011

Page 36: Status of  LHC Performance

Schedule

LHC status2-8-2011 36

Page 37: Status of  LHC Performance

What are days for?

LHC status2-8-2011

Ah, solving that questionBrings the priest and the doctorIn their long coatsRunning over the fields.

Days

Calendar 89

Special runs 3 (say...)

Technical stop 5

TS recovery 1

Ramp-up 3

Machine development 5

Floating MD 2

Physics 70

Protons: 2nd August to 29th October inclusive

+25 ns studies to come during MDs (to sort out injection and beam stability issues) and possibly an operational development period to validate scrubbing and future operation

37

70 days at present performance, reasonable efficiency ~2 fb-1

Page 38: Status of  LHC Performance

Start August Excellent peak luminosity performance & production rates Very good through inject, ramp, squeeze, collide

Effective turn around time is long: problem resolution, accesses etc…cruising we are not

Short fills – exposed to the intersecting failure space of a number of complex systems with huge number of components. This failure space is inflated by high intensity and high luminosity

Holding is sometimes more effective than raising Although the effects of “conditioning” and mitigation (UFOS,

vacuum, RF, QPS, SEUs) is clear… Will not be pushing bunch intensity aggressively until things

settle down

Conclusions

2-8-2011 38LHC status

Page 39: Status of  LHC Performance

Curate’s egg

LHC status 392-8-2011

“parts of it are excellent”


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