test ramp for emittance calibration
DESCRIPTION
Test Ramp for Emittance Calibration. M. Kuhn, V. Kain, F. Roncarolo, B. Dehning, A. G. Ollacarizqueta, G. Trad, J. Gras, J. Emery. Motivation: Emittance versus Intensity Loss. Results from MD I – 15/5/2012: Emittances decrease during the ramp - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/1.jpg)
LHC
Test Ramp for Emittance Calibration
M. Kuhn, V. Kain, F. Roncarolo, B. Dehning, A. G. Ollacarizqueta, G. Trad, J. Gras, J. Emery
1
![Page 2: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/2.jpg)
LHC
Motivation: Emittance versus Intensity Loss
o Results from MD I – 15/5/2012:− Emittances decrease during the ramp
o Emittance shrinkage coincides with intensity loss…o Beta functions at wires? Wire scanner calibration?
2
![Page 3: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/3.jpg)
LHCMD II (25/6/2012)
Test Ramp for Emittance Calibration
o Conditions:− intermediate collimator settings − 2 bunches per beam with different emittances− Cycle: RAMP - SQUEEZE - COLLISION
o Wire scanner calibration− Orbit bumps at injection and flattop
o K-Modulation− Flattop: point 4− Squeeze: point 4 and triplets
o Wire scans during ramp, squeeze and collision o Luminosity data
3
![Page 4: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/4.jpg)
LHC
o Orbit bumps at 450 GeV and 4 TeVo Going from +3mm to -3mm in 1mm steps
− Wire scannerB1V, B2H andB2V similar
o Calibration OK− bump versus wire scanner response fully consistent at flattop and injection− The slopes are 1 within the measurement error− No energy dependence
Wire Scanner Calibration
4
![Page 5: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/5.jpg)
LHCK-Modulation @ 4TeV
5
BEFORE THE SQUEEZE AFTER THE SQUEEZE
BEFORE THE SQUEEZE AFTER THE SQUEEZE
Bea
m 1
Bea
m 2
• RQ5.L4• RQ5.R4
• RQ6.R4• RQ7.R4
• RQ5.R4• RQ5.L4 • RQ6.L4
G. Trad
![Page 6: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/6.jpg)
LHC
K-Modulation @ 4TeV
Before Squeeze: After Squeeze:
Before Squeeze
G. Trad6
![Page 7: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/7.jpg)
LHC
o Noisy tune measurements specially at flattop with unsqueezed optics
o Preliminary results to be compared− With last MD data (K-Modulation @ 450 GeV)− With the Beta-Beating measurements
K-Modulation @ 4 TeV
G. Trad7
![Page 8: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/8.jpg)
LHCEmittance Growth
o Look at emittance growth during rampo Calculate emittance from luminosity at collision
− Compare with wire scan data
o Emittance determined with measured betas at injection and flattop from Rogelio’s team, interpolation in between
o Error bars indicate difference between in and out wire scan
8
![Page 9: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/9.jpg)
LHC
o Results from MD II − intermediate collimator settings to not lose intensity
o Still emittance shrinkage during ramp, but less pronounced than in last MDo Almost no intensity loss – not clear whether correlated to emittance
decrease!
Emittance versus Intensity Loss
9
![Page 10: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/10.jpg)
LHC
o Convoluted emittance:− Used measured beta at β* = 0.6m for wire scanners− Single bunch intensity and bunch length
Luminosity: β* error of 15 %, crossing angle error 15 μrad No wire scan data for B2V
o Emittances from wire scans significantly smaller than emittances from luminosity (especially ATLAS)
o Need to check with k-modulation betas
Luminosity Data
10
εL [μm] Wire Scan From CMS Luminosity
From ATLAS Luminosity
Bunch 1 4.94 +/- 0.60 5.77 +/- 0.87 6.88 +/- 1.03Bunch 2 2.55 +/- 0.50 3.05 +/- 0.46 3.80 +/- 0.57
![Page 11: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/11.jpg)
LHCSummary
o Preliminary results so far…
o Emittances measured by wire scanners decrease through the ramp.− …despite much reduced intensity loss
o MD to − measure emittances with wires during ramp, squeeze and collisions− measure betas at wires− Re-calibrate wires− Compare to data from luminosity− …to finally know whether the normalized emittances are really smaller at flattop
11
![Page 12: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/12.jpg)
LHC
Back up
12
![Page 13: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/13.jpg)
LHC
o Emittances grow until ~ 1/3 of Ramp, then decreaseo Except for Beam 2 H
Emittance at Ramp
13
![Page 14: Test Ramp for Emittance Calibration](https://reader035.vdocuments.us/reader035/viewer/2022062816/56814c04550346895db903f1/html5/thumbnails/14.jpg)
LHCAfter Squeeze
14