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