Transcript LHC Commissioning Phases: Phase 1-

LHC Commissioning Phases
Detailed Measurements at 450 GeV
presented by Frank Zimmermann
on behalf of the LHCCWG
Particular thanks to
Stefano Redaelli, Massimo Giovannozzi, the EICs,
Roger Bailey, Stephane Fartoukh, Brennan Goddard,
Rhodri Jones, Verena Kain, Mike Lamont,
Ralph Steinhagen, Jan Uythoven, Jorg Wenninger
LHC Technical Committee, 11/04/2007
LHC Commissioning Phase 4 – Detailed Measurements at 450 GeV
• Phase A.4: Detailed Measurements at 450 GeV
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Objectives
Entry conditions
Preconditions and tools
Commissioning procedures with a few examples
Exit conditions
• Summary
LHC Technical Committee, 11/04/2007
LHC Stage A: Commissioning phases
Phases for full commissioning Stage A (pilot physics run)
Phase
A.1
A.2
A.3
A.4
A.5
A.6
A.7
A.8
A.9
A.10
A.11
Description
Injection and first turn: injection commissioning; threading, commissioning beam instrumentation.
Circulating pilot: establish circulating beam, closed orbit, tunes, RF capture
450 GeV initial commissioning: initial commissioning of beam instrumentation, beam dump
450 GeV optics: beta beating, dispersion, coupling, non-linear field quality, aperture
Increasing intensity: prepare the LHC for unsafe beam
Two beam operation - colliding beams at 450 GeV
Snap-back and ramp: single beam
Bringing beams into collision: adjustment and luminosity measurement
7 TeV optics: beta beating, dispersion, coupling, non-linear field quality, aperture
Squeeze: commissioning the betatron squeeze in all IP's
Physics runs: physics with partially squeezed beams, no crossing in IP1 and IP5
Basic Objectives:
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establish linear optics
first assessment of orbit & optics stability
chromaticity control preparing for the ramp
collimator setup in view of higher stored beam energies
aperture validation
LHC Technical Committee, 11/04/2007
Detailed Measurements at 450 GeV – Overview of Steps Involved
Step
Activity
Priority
A.4.1
A.4.2
Measure & correct closed orbit
Measure & correct linear optics (b, D, ...)
1
1
A.4.3
Measure and correct transverse aperture
1
A.4.4
Measure momentum aperture
1
A.4.5
Commission collimators & protection devices
1
A.4.6
Detailed rf measurements
1
A.4.7
Measure & correct global non-linear optics
1 to 3
A.4.8
Commission non-linear correctors
1 to 3
A.4.9
Commission IR bumps
2
A.4.10
Perform injection matching
2
A.4.11
Beam loss studies
2
Priority categories (71th LTC):
• absolutely mandatory,
• should be done if possible,
• would be nice if it could be done
LHC Technical Committee, 11/04/2007
Detailed Measurements at 450 GeV – Beam Entry Conditions
Beam Entry conditions:
• both beams circulating with lifetime > 1h
• separate commissioning for beam 1 and beam 2
• some steps require both beams simultaneously
(1) orbit/optics correction in the common regions; (2) D1/D2
transfer function checks; (3) Parallel separation bumps.
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coasting beams (LHC) and Inject&Dump mode (few s)
only single bunches, intensities up to a few 1e10 protons
nominal beam emittance (value agreed for ramping)
reproducible emittance from injector chain
reduced intensity for studies involving full beam loss
i.e. momentum aperture, injection failure scenarios;
for these use a few 1e9 protons (scraping in the SPS?)
LHC Technical Committee, 11/04/2007
Detailed Measurements at 450 GeV – Optics Entry Conditions
Optics Entry conditions:
• nominal tunes if possible
(otherwise, need to first correct coupling on special
commissioning working point)
• stable/reproducible optics and orbit
• reproducible injected beams shot by shot
• chromaticity under control
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – RF & Magnets Entry Conditions
RF & Magnets Entry conditions:
• RF fully commissioned for pilot++ intensities (see A.3)
• radial steering fully commissioned
• transverse damper commissioned; possibility to switch it
ON/OFF
• COD polarity checked and calibrated
• full HWC of “higher order” corrector circuits & CCC control
- lattice correctors: coupling (a2), chromaticity (b3), Landau octupoles (b4)
- spool pieces: sextupole (b3), octupole (b4), decapole (b5)
- MQX correctors: orbit, coupling, dodecapoles (b6)
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detector magnets OFF
spectrometers at IP2 and IP8 OFF
HWC of steering magnets for IP separation/crossing bumps
both signs of IP bumps available
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – Instrumentation Entry Conditions
Instrumentation Entry conditions:
• BPM system: - polarity & calibration checked; expected resolution for
single bunches of 1 to a few 1e10 p: closed orbit = 10 micron; trajectory = 50100 micron; - sum signal available [imposes constraints for the operation with
two beams!] ; - acquisition synchronized with other devices (kickers, wires, ...) ;
- turn-by-turn acquisition available; - >1000-turn acquisition; - simultaneous
1000-turn acquisition for both beams
• BCT: - DC BCT's cannot be used at pilot or pilot+ intensities; - measurements
must rely on the fast-BCT measurements (10% accuracy with 1e10;1%
accuracy with 1e11!); - turn-by-turn acquisition synchronized to
kicker/bpm/wires/blm
• Beam size measurements: - Wire scanners [priority 1]; - Ionization
profile monitors (IPM's) [priority 3]; - Synchrotron radiation monitor [priority 2];
Absolute calibration <~20% for the beam size; What is the minimum time
between consecutive measurements? (Implications, e.g. on the minimum risetime of orbit bumps to measure beam profiles before and after beam scraping)
• Beam loss monitors: - Signal acquisition for all the available monitors; Movable monitors ready for use; - Dedicated fast acquisitions with t_acq<20ms
• Screens: Emittance measurements in the TL for pulse-to-pulse monitoring
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – Controls Entry Conditions
Controls Entry conditions:
• YASP steering program (already available): - Correct and steer
the closed orbit; Correct and adjust single (first) turn (e.g., re-tuning of injection
areas after orbit bumps); 3- and 4-corrector bumps with variable amplitude;
optics model to calculate Dp/p
• Automatic application for SLIDING BUMPS; could be part of
YASP or use YASP
• Collimator control software
• Control, acquisition, display and logging of all required BI
monitors (BPM, BCT, BLM, wires, etc...) and devices (tune
kickers, aperture kickers, ...); Simultaneous data taking is crucial!
• "Aperture database" - Online update for "as-measured"
aperture model (location of aperture bottlenecks, bump settings that
optimize aperture).
• (On-line) optics model to get (propagate) optics - MAD-X online
model or multi-turn application with MAD-X interface
• Control of AC dipole from Q meter; AC dipole interlock
commissioned
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – Addt’l HW Entry Conditions
Additional Hardware Entry conditions:
• tune/aperture kickers
(commissioned already in A.3)
• first use of collimator subset
• beam scraping at the SPS
(generate "pencil" beams or small emittances)
• additional devices for aperture measurements commissioning of emittance blow up (?);
transverse quadrupole noise? RF noise?
• AC dipole
LHC Technical Committee, 11/04/2007
Detailed Measurements at 450 GeV – Stage A.4.1 – Closed Orbit
Step
A.4.1
A.4.1.1
A.4.1.2
A.4.1.3
Activity
Measure and correct closed orbit
Measurement and correction of each arc
Measurement & correction of each IR (needs
another iteration with 2 beams)
Iterate with improved optics knowledge if/as needed
Priority
1
ABP/OP
1
ABP/OP
1
ABP/OP
2
reference closed orbit for the following phases;
orbit corrected within tolerance (peak+r.m.s.);
measurement accuracy to be defined;
much of this done in earlier phases already;
first detailed estimates of orbit stability and reproducibility
LHC Technical Committee, 11/04/2007
example: A.4.1 – sensitivity of orbit feedback to b beat
R. Tomas,
LHCCWG#8
R. Steinhagen,
LHCCWG#6
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – Stage A.4.2 – Linear Optics
Step
A.4.2
A.4.2.1
A.4.2.2
A.4.2.3
A.4.2.4
Activity
Measure and correct linear optics
Polarity checks of MQT, MQS, MQSX
Coupling
Beta beat
Dispersion
Refined optics model, response matrix, BPM
A.4.2.5
calibration (no beam time)
Generation of new settings for correctors if
A.4.2.6
necessary(?)
Additional local beta measurements with KA.4.2.7
modulation (IR's, wires, collimators, ...)
ABP/OP
ABP/OP
ABP/OP
ABP/OP
ABP/BI/
OP
Priority
1
1
1
1
1
2
ABP/OP
2
ABP/OP
2
reference optics for following phases;
beta beat measured (and corrected) within tolerance;
dispersion measured (and corrected) within tolerance;
b and D are corrected together;
first detailed estimates of optics stability and reproducibility;
coupling, beta-beat & dispersion correction may need second iteration
with 2 beams
LHC Technical Committee, 11/04/2007
example: A.4.2.1 - coupling correction
R. Tomas,
LHCCWG#8
LHC Technical Committee, 11/04/2007
example: A.4.2.2 - beta beat correction
R. Tomas,
LHCCWG#8
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – Stage A.4.3 – Transv. Aperture
Step
Activity
A.4.3
Measure and correct transverse aperture
A.4.3.1 Commission sliding bump software
Measure global aperture measurements with kick + loss
A.4.3.2
method and/or by exciting orthogonal correctors
A.4.3.3 Apply local bumps to center orbit in aperture [if needed]
Iteration of A.4.3.2 and A.4.3.3 until we achieve
A.4.3.4
tolerances [if needed]
A.4.3.5 Commission the aperture database, if available
A.4.3.6 Dedicated local aperture measurements (IR's, dump,..)
Commission other measurement tools (emit. blow-up,
A.4.3.7
AC dipole), cross checks
Priority
1
ABP/OP
1
ABP/OP
1
ABP/OP
2-1
ABP/OP
2-1
ABP/OP
ABP/OP
ABP/BI/
OP
2
2
3
first global aperture measurements;
detailed local aperture measurements in critical locations;
optimization of local bottlenecks that become critical at 7 TeV;
priority 2 becomes 1 if we squeeze after ramp
LHC Technical Committee, 11/04/2007
example: A.4.3.6 – local aperture measurements
S. Redaelli,
LHCCWG#11
Established methods based on BCTs are also available;
inject & dump mode possible
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – A.4.4 – Momentum Aperture
Step
Activity
A.4.4
Measure momentum aperture
A.4.4.1 Radial steering scans (full beam scraping)
LHC Technical Committee, 11/04/2007
Priority
1
ABP/OP
1
D’d Measurements at 450 GeV – A.4.5 – Collimators & PDs
Step
A.4.5
Activity
Commission collimators & protection devices
Beam based alignment of required collimators (TCPs,
A.4.5.1
TCDQ, TDIs, TCTs, some TCSs)
Measurements of local beta-functions and beam sizes
A.4.4.2
by collimator scans
Enter beam-based information into database, define
A.4.4.3
reference settings, ...
prepare for limited higher stored energies
(ramp or higher intensities at 450 GeV);
may also be done in phase A.5
LHC Technical Committee, 11/04/2007
Priority
1
Coll.
Team
Coll.
Team
Coll.
Team
1
1
1
example: A.4.5.1 – beam-based collimator alignment in SPS
S. Redaelli,
Chamonix
2005
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – A.4.6 – RF Measurements
Step
A.4.6
A.4.6.1
A.4.6.2
Activity
Perform detailed RF measurements
Final commissioning of the radial loop (if not already
done)
Longitudinal profile (parasitic)
LHC Technical Committee, 11/04/2007
Priority
1
RF
1
RF
1
D’d Measurements at 450 GeV – A.4.7 – Global Nonlinear Optics
Step
A.4.7
A.4.7.1
A.4.7.2
Activity
Measure and correct global nonlinear optics
Tune versus Dp/p -> Q', Q'', ...
Tune vs amplitude
LHC Technical Committee, 11/04/2007
Priority
1
ABP/OP
1
ABP/OP
2
D’d Measurements at 450 GeV – A.4.8 – Nonlinear Correctors
Step
Activity
A.4.8
Commission nonlinear correctors
A.4.8.1 Commission control of corrector circuits if not done
Normal sextupole - polarity checks, local measurement
A.4.8.2
and correction
Skew sextupole - polarity checks, local measurement
A.4.8.3
and correction
Normal octupole - polarity checks, local measurement
A.4.8.4
and correction
Normal decapole - polarity checks, local measurement
A.4.8.5
and correction
A.4.8.6 Polarity checks of non-linear MQX correctors
LHC Technical Committee, 11/04/2007
Priority
1
ABP/OP
1
ABP/OP
1
ABP/OP
3
ABP/OP
3
ABP/OP
3
ABP/OP
3
example: A.4.8.2 – check of normal sextupole circuits
local b3 correction: chromatic phase advance
F. Zimmermann,
Chamonix 2003;
LHCCWG#10
simulated Df for 1s kick for dp/p=10-3 and dp/p=0;
3 cases: (1) no spool piece mispowered,
(2) sextupole circuit KCS45 missing (BPMs 194 to 257),
(3) decapole circuit KCD45 missing
we can detect missing b3 circuits, but not missing b5!
LHC Technical Committee, 11/04/2007
D’d Measurements at 450 GeV – A.4.9 – IR Bumps
Step
A.4.9
A.4.9.1
A.4.9.2
A.4.9.3
Activity
Commission IR bumps
Commission separation bumps in all IP's
Commission spectrometer compensation in IR8
Commission spectrometer compensation in IR2
priority depends on spectrometer status & physics plan
LHC Technical Committee, 11/04/2007
Priority
1-2
ABP/OP
1-2
ABP/OP
2
ABP/OP
3
D’d Measurements at 450 GeV – A.4.10 – Injection Matching
Step
A.4.10
Activity
Perform injection matching
trajectory, betatron and dispersion; matching with
A.4.10.1 injection (and/or multi-turn) screens; only necessary in
case of inacceptable emittance growth
Priority
2-1
ABP/BT/
OP
acquisition system and software for OTR injection matching monitor
available only for LHC Phase II (75-ns operation);
fine tuning is done in later phase, e.g. A.5
LHC Technical Committee, 11/04/2007
2-1
D’d Measurements at 450 GeV – A.4.11 – Beam Loss Studies
Step
A.4.11
Activity
Beam Loss Studies
A.4.11.1
Beam loss map studies
A.4.11.2
Estimate collimation cleaning inefficiency
LHC Technical Committee, 11/04/2007
Priority
2
Coll.
Team/
BI
Coll.
Team/
BI
2
2-3
Detailed Measurements at 450 GeV – Exit Conditions
Main exit conditions:
Reference orbit and linear optics under control
(both beams) as precondition for ramp.
Nominal injection optics established.
Collimators and protection devices set up for
higher stored energies (ramp or intensity increase);
- much of this could be done also in A.5
Chromaticity measurements & corrections
available for ramp.
Machine aperture at injection known.
First assessment of stability & reproducibility.
LHC Technical Committee, 11/04/2007
Summary
• Phase A.4 :
– prepare for ramp and for higher intensity
• Main focus is on:
–
–
–
–
–
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orbit control
linear optics control
chromaticity control
aperture control
set up of collimators & protection devices (could be in phase A.5)
stability & reproducibility
• At the end of this phase:
- we can ramp pilot bunches to 7 TeV (phase A.7)
- and/or increase the bunch intensity & # bunches (phase A.5)
LHC Technical Committee, 11/04/2007
Comments
• Detailed measurements at 450 GeV will probably be
interleaved with pilot-bunch ramps to higher energy
• Sorting out D1/D2 transfer function errors may later on require
measurements with triplet alignment optics at 450 GeV
LHC Technical Committee, 11/04/2007
References
• Web documentation
LHC Commissioning procedures,
LHC Commissioning pages
Documentation and Procedures: Phase A4
[S. Redaelli, EICs+V. Kain]
• Pertinent LHCCWG presentations:
Circulating Beam and RF Capture LHCCWG#3
[G. Arduini, A. Butterworth]
Magnetic Field Fill-to-Fill Reproducibility and Differences Between the Two Apertures
LHCCWG#14
[L. Bottura]
Beam Instrumentation - BPM, BLM, BCT, Transverse Diagnostics
LHCCWG#3
[R. Jones]
Commissioning Procedures LHCCWG#5 & #6
[V. Kain]
Snapback and Ramp with Single Beam LHCCWG#7
[M. Lamont]
450 GeV Optics: IR Aperture and IR Bumps LHCCWG#13
[Y. Papaphilippou]
450 GeV Optics – Mechanical Aperture and Momentum Aperture LHCCWG#11
[S. Redaelli],
Overview of Feedbacks and Implications for Commissioning LHCCWG#6
[R. Steinhagen]
450 GeV Optics – Beta Beating, Coupling, Dispersion LHCCWG#8
[R. Tomas]
Response Matrix Measurements and Analysis LHCCWG#9
[J. Wenninger]
Tracking error measurement and correction LHCCWG#17
[J. Wenninger]
Nonlinear Field Quality Checks LHCCWG#10
[F. Zimmermann]
Initial Measurement Program LHCCWG#3
[F. Zimmermann]
Summary of Parameter Tolerances LHCCWG#19
[F. Zimmermann]
What to Do If We Cannot Get in Tolerance LHCCWG#19
[F. Zimmermann]
Proposed Beam Measurement Program in 2007 LHCCWG#19
[F. Zimmermann]
• Others:
Field Quality Specification for the LHC Main Dipole Magnets, LHC PR 501
Measurement of the Betatron Tunes and of the Chromaticity and Amplitude
Detunings in the LHC Rings, LHC-B-ES-000X.00.rev0.2
Proceedings Chamonix XV
Proceedings Chamonix Chamonix XII
Procedures and accuracy estimates for beta-beat correction in the LHC EPAC’06
LHC Technical Committee, 11/04/2007
[S. Fartoukh, O. Brüning]
[S. Fartoukh, J.P. Koutchoukl]
[R. Tomas et al]