Brief Summary of LPA MD on 19 June 2012 Jose Abelleira, Xavier Buffat, Chandra Bhat, Karel Cornelis,...
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Transcript of Brief Summary of LPA MD on 19 June 2012 Jose Abelleira, Xavier Buffat, Chandra Bhat, Karel Cornelis,...
Brief Summary of LPA MD on 19 June 2012
Jose Abelleira, Xavier Buffat, Chandra Bhat, Karel Cornelis, Riccardo De Maria, Stephane
Fartoukh, Rossano Giachino, Eva Barbara Holzer, Mike Lamont, Themis Mastoridis, Alick
Mcpherson, Kazuhito Ohmi, Giulia Papotti, Tatiana Pieloni, Ferdico Roncarolo, Ghislain Roy, Belen Salvachua, Daniel Valuch, Frank
Zimmermann, …
• started 3.5 hours late (LHC RF crowbar repair, PS 10–MHz cavity), then 1 h machine set up; first MD beam injected ~13:45• Special hypercycle for Piwinski MD• 2 bunches of 1.5 e11 per bunch (+pilot), go to collision tunes, &
collapsed crossing angles at IP1 and 5, and separation at IP 1,5, and 8; then looked for collisions. Filling scheme with one bunch colliding in IP1,5,and 8, and other bunch colliding in IP 8 only.• Impossible to find collisions at ATLAS and CMS, but LHCb could be
optimized... decision to dump & re-inject with higher intensity• 2 bunches of ~2.4e11 injected without separation bump, IP1/IP5
crossing angle at zero, and collision tunes – Clear luminosity signals in ATLAS and LHCb –No clear Luminosity readings from CMS (some signal towards
the end of the MD) ; problem with BSRT data acquisition LHCb spectrometer ramped down in steps to zero.
• LHCb spectrometer was left at 0 strength after the MD
MD history
LPA MD conditions• 2.4e11 / bunch; 2 bunches per beam• 1st bunch collides in IP 8 only• 2nd bunch collides in IPs 1, 5 and 8• injection energy, 1.5 ns bunch length, e~2 mm • ADT off, orbit feedback off, • TCTs at coarse settings, IR angle bumps zeroed in IPs
1 and 5 • IP8 crossing angle 4 mrad, 2 mrad, 0 (varied with
spectrometer strength)• collision tunes• estimated Piwinski angles ~ 1.1, 0.6, 0
largest Piwinski angle ever!
LPA MD overview
CMS lumi
signal appears at last
ATLASlumi signalreduced(steeringeffect)
LHCb luminosity signal zero in the database
only short quiet period (30 s?)at 50% spectrometer strength
LPA MD overview with IP correctors
X. Buffat, T. Pieloni
LPA MDbunch intensities
X. Buffat, T. Pieloni
LPA MD bunch intensities
X. Buffat
100%
50%~15% 100%
50%~15%
bunch with 3 collisions loses much more intensity; steepest loss at 50% of LHCb spectrometer strength; best lifetime at 0 strength
Jose Abelleira, Chandra Bhat, Xavier Buffat, Karel Cornelis, Riccardo De Maria, Rossano Giachino, Mike Lamont, Themis Mastoridis, Alick Mcpherson, Giulia Papotti, Tatiana Pieloni, Ghislain Roy, Belen Salvachua, Daniel Valuch, Frank Zimmermann, + …
qualitatively consistent with expectation
MD simulation by K. Ohmi
1 day
2 h
EmitX beam 1 EmitX beam 2 EmitY beam 1 EmitY beam 2
17:00 1.95+/-0.01 mm(1 collision)2.07+/-0.01 mm(3 collisions)
2.17+/-0.00 mm(1 collision)2.56+/-0.02 mm(3 collisions)
17:17 2.7+/-0.1 mm(1 collision)2.10+/-0.03 mm(3 collisions)
2.0+/-0.1 mm(1 collision)1.6+/-0.1 mm(3 collisions)
2.17+/-0.01 mm(1 collision)1.72+/-0.03 mm(3 collisions)
2.11+/-0.01 mm(1 collision)1.64+/-0.01 mm(3 collisions)
17:35 2.53+/-0.01 mm(1 collision)2.0+/-0.1 mm(3 collisions)
2.01+/-0.01 mm(1 collision)1.56+/-0.02 mm(3 collisions)
2.11+/-0.04 mm(1 collision)1.67+/-0.02 mm(3 collisions)
2.07+/-0.05 mm(1 collision)1.53+/-0.08 mm(3 collisions)
LPA MD bunch emittance
bunch with 3 collisions shrinks
BBQ
X. Buffat, T. Pieloni
BBQ Almost fully saturated
X. Buffat, T. Pieloni
BSRTsGot stuck on single bunch the one colliding in IP1-5-8…
No apparent reasons for this…
X. Buffat, T. Pieloni
BSRT software had got stuck!?
R. De Maria
bunch length
Profile MeasurementsApproximate locations
C. Bhat
Bunch 1 Traces:Bunch Intensity= 2.4E11ppb(2nd Injection)
s= 0.43 nsec (Gaussian)FWHM=1.00 nsecRelative Area=0.32
s= 0.45 nsec (Gaussian)FWHM=1.07 nsecRelative Area=0.28
Start of the MD End of the MD
C. Bhat
Bunch 2 Traces:Bunch Intensity= 2.4E11ppb(2nd Injection)
s= 0.42 nsec (Gaussian)FWHM=0.98 nsecRelative Area=0.22
s= 0.44 nsec (Gaussian)FWHM=1.05 nsecRelative Area=0.14
Start of the MD End of the MD
C. Bhat
plan• review luminosity data from LHCb and CMS
(not in logging database)
• further analysis intensity and luminosity lifetime
for different spectrometer strengths
• MD note soon – editor Jose Abelleira