Transcript LHC beam operation past, present, future Mike Lamont for the LHC team 2011 – recap 75 ns 50 ns Squeeze further Increase number of bunches Scrubbing Increase bunch intensity Initial 11/3/2012 commissioning Reduce beam size from injectors LHC status.

LHC beam operation
past, present, future
Mike Lamont
for the LHC team
2011 – recap
75 ns
50 ns
Squeeze
further
Increase
number of
bunches
Scrubbing
Increase bunch
intensity
Initial
11/3/2012
commissioning
Reduce beam
size from
injectors
LHC status
Starting out
• Efficient commissioning leading into 75 ns
operation
• Intermediate energy run
• Scrubbing rocky but successful
– Dynamic effects: synchrotron radiation, e-cloud 
Scrubbing  reduction of the LHC pressure
Decision: go with 50 ns
11/3/2012
LHC status
Number of bunches++
• End April: “fabulous performance”
• A little bit of caution – extended period
at 1092 bunches
• Pushing 1.3e11 ppb but high beam
intensity issues starting to show
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Blow-up of some bunches at injection
E-cloud solenoids, triplet vacuum, beam screen cooling
108 b injection sort of OK, worry about scraping in the SPS
Injection kicker heating, vacuum kicking off in IR 8
RF arc detectors – false dumps
Abort gap population
SEUs starting to show
Collimator heating
11/3/2012
LHC status
1033
LHC machine breaks 3 new world records at 10h41 Sunday 29 May:
2 x 1092 bunches colliding, luminosity above 1.2 x 10^33, and a
beam energy of 73 MJ.
11/3/2012
LHC status
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Looking towards 1380
bunches
Strong emittance blow-up at injection
• Chromaticity stability, persistent current decay compensation
• Eventually suppressed by octupoles at 450 GeV
Bunch length control in ramp
Satellite collisions tested
RF versus intensity versus trips – worrying about couplers – dump
on cavity trip deployed
Vacuum at 2&8 - instabilities
Instrumentation issues
UFO storms
High losses at collimators
1 SEU dump per day
Trim quad circuits tripping during squeeze
11/3/2012
LHC status
15th June: 1 fb-1
Summer - now what do we do?
• July: starting to look encouraging…
• August: getting so worried about SEUs we had a
brainstorming
Decision to push:
• beam from the injectors
• and a mini-Chamonix
• squeeze
11/3/2012
LHC status
Beam from injectors
Excellent performance – years in the preparation
Best in 2011 with 50 ns:
• ~1.45 x 1011 ppb
• ~2.3 microns into collision
11/3/2012
LHC status
Design with 25 ns:
• 1.15 x 1011 ppb
• Normalized emittance 3.75 microns
IR1 and IR5 aperture at 3.5
TeV
2011’s “platinum mine”
~3 cm
We got 4-6 sigmas more than the
expected 14 sigma
Triplet aperture compatible with a
well-aligned machine, a well centred
orbit and a ~ design mechanical
aperture (small tolerance)
~600 m
11/3/2012
LHC status
Stefano Redaelli
Squeeze
• Beta* = 1 m – big success – 3.3e33 cm-2s-1
• Pushing bunch intensities to 1.35e11
• Collimator interlocks, PADs/MADs, injection
quality, vacuum, collimator heating, Alice
background, b2 instability, RF de-bunching,
tune feedback in squeeze
11/3/2012
LHC status
Impressive final run in
Mirko Pojer
11/3/2012
LHC status
Very positive ending
Ion man
11/3/2012
LHC status
2011
• Another remarkable year
• It was nearly always a battle…
• Remarkably no real show stoppers
• Successfully took on:
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11/3/2012
Total intensity
Bunch spacing
Bunch intensity
Emittance
Beta* & aperture
LHC status
Of note
• Operational robustness
– Precycle, injection, 450 GeV, ramp & squeeze &
collisions
• Machine protection
– Unpinned by superb performance of machine
protection and associated systems
– Rigorous machine protection follow-up, qualification
and monitoring (Post Mortem analysis, MPP, rMPP)
• Routine collimation of 110 MJ LHC beams
without a single quench from stored beams.
11/3/2012
LHC status
Operation efficiency
• Overall efficiency
– Pretty good considering that this is the LHC
– Overall time in stable beams 34%
• Premature dumps
– 50% of all STABLE BEAMS fills lasted less than 3
hours
34%
11/3/2012
LHC status
Radiation to electronics (R2E)
xMas-Mitigation crucial: patch, shielding, relocat.
Patches to continue during 2012
Particular emphasis (analysis) of ‘new’ failures
11/3/2012
LHC status
Concerted program of investigations, simulations, tests with beam …
11/3/2012
LHC status
Tobias Baer
Vacuum
• Unexpected pressure rise (10-6 mbar) observed in LSS2-LSS8 (D1) and close
to CMS: bad RF contact (x-rays inspection) interventions done in 2 & 8 &
CMS to resolve RF finger issues - shouldn't be a problem in 2012.
CMS
LSS2
11/3/2012
LHC status
TDI – beam screen heating
11/3/2012
LHC status
2011 to 2012
• Well organized, productive Xmas technical stop
– Lot of R2E related work
– Plus consolidation and improvements of many systems
• Vacuum consolidation to address successfully diagnosed
causes of instabilities in 2011
• Injection collimators issues diagnosed and understood spare in preparation - fingers crossed in the meantime
• Cool-down of machine exactly on schedule - cryogenics
demonstrating full mastery…
• Very smooth hardware commissioning including careful
quench-less commissioning of main circuits to 4 TeV
• Machine checkout proceeding well - good for beam next
Tuesday afternoon
11/3/2012
LHC status
2012 strategy
4 TeV
β*=0.6m→0.7m→0.9m
50 ns
∫Ldt = 5 fb-1 in June?
∫Ldt = 15-19
LHCb ∫Ldt=1.5
fb-1
TCP gap=2.2mm
fb-1
Dumps=30-50
Pile-Up=26-35
Lpeak=5-6.8 1033 cm-2s-1
SPS ε= 2 μm
IP1 β*=500m
SPS Np= 1.6 1011
p-Pb: 3.5 TeV or 4 TeV
β*=(0.6,0.6,0.6,3)m
11/3/2012
LHC status
∫Ldt = 15- 23 nb-1
Rogelio Tomas
Collimator settings 2012
2012: tight settings
Collimation hierarchy has to be
respected in order to achieve
satisfactory protection and
cleaning
11/3/2012
LHC status
TCP 7
TCSG 7
TCLA 7
TCSG 6
TCDQ 6
TCT
Aperture
σ
4.3
6.3
8.3
7.1
7.6
9.0
10.5
How tight?
Norway
Iberian
peninsula
Intermediate settings (2011):
~3.1 mm gap at
primary collimator
11/3/2012
Tight settings:
~2.2 mm gap at
primary collimator
LHC status
2012 run configuration
• Energy – 4 TeV
– Low number of quenches (as in 2011) assumed
• Bunch spacing - 50 ns
• Collimator settings – tight
– As discussed – NB not yet proven operationally
• Atlas and CMS beta* - 60 cm
– with 70 cm and 90 cm as fallbacks
• Alice and LHCb beta* - 3 m
– Natural satellites versus main bunches in Alice
11/3/2012
LHC status
Bunch spacing
Performance from injectors
Bunch
spacing
From
Booster
Protons per
bunch (ppb)
Emittance H&V
[mm.mrad]
150
Single batch
1.1 x 1011
1.6
75
Single batch
1.2 x 1011
2.0
50
Single batch
1.45 x 1011
3.5
50
Double batch
1.6 x 1011
2.0
25
Double batch
1.2 x 1011
2.7
N kb f
N kb f g
L=
F=
F
*
4ps xs y
4pen b
2
11/3/2012
2
LHC status
2012 LHC schedule Q1/Q2
1
2
3
4
11/3/2012
LHC status
2012 LHC schedule Q3/Q4
6
5
11/3/2012
High beta* runs for ALFA and TOTEM
LHC status
Van der
Meer scans
2012 - breakdown
Days
2
21
Machine check-out
Commissioning with beam
Machine development
Technical stops
Scrubbing (25 ns)
22
20
3
Technical stop recovery
Initial intensity ramp-up
Proton running
6
~21
~126
Special runs
Ion setup
~8
4
Ion run
24
11/3/2012
LHC status
~150 days
50 ns performance estimate
4 TeV, 50 ns, 1380 bunches, 1.6e11, 2.5 microns
150 days of proton physics (assuming similar
efficiencies to 2011)
Beta* Collimators Peak Lumi
[cm]
[cm-2s-1]
90
Intermediate
5.1e33
70
Tight
6.2e33
60
Tight
6.8e33
11/3/2012
Int. Lumi
[fb-1]
12.1 – 14.5
14.7 – 17.6
16.2 – 19.3
LHC status
Pile-up
Increase
in peak
26
31
+22%
35
+10%
25 ns performance estimate
4 TeV, 25 ns, 1380 bunches, 1.6e11, 2.5 microns
140 days of proton physics (extra scrubbing required)
Beta*
[cm]
Collimators
Peak Lumi
[cm-2s-1]
Int. Lumi
[fb-1]
Pile-up
80
Tight
3.8e33
8.3
10
Conclusion: 25 ns not competitive with 50 ns
11/3/2012
LHC status
11/3/2012
LHC status
Conclusions
• Good performance in 2011 from working on all available
parameters
• Very definitely exploring the effects of high intensity
beams
– SEUs, beam induced heating, vacuum instabilities…
– Operational efficiency suffering as a result
• Main gain in 2012 is use of tight collimator settings and
reduced beta*
– 5 to 6 x 1033 cm-2s-1 and 15 fb-1 should be possible
• Hope for improved operational efficiency
– R2E mitigation measures
– but partially countered by increased peak performance
• Another long, interesting year in prospect…
11/3/2012
LHC status