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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

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test ramp for emittance calibration

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
Motivation: Emittance versus Intensity Loss
  • Results from MD I – 15/5/2012:
    • Emittances decrease during the ramp
  • Emittance shrinkage coincides with intensity loss…
  • Beta functions at wires? Wire scanner calibration?
md ii 25 6 2012
MD II (25/6/2012)

Test Ramp for Emittance Calibration

  • Conditions:
    • intermediate collimator settings
    • 2 bunches per beam with different emittances
    • Cycle: RAMP - SQUEEZE - COLLISION
  • Wire scanner calibration
    • Orbit bumps at injection and flattop
  • K-Modulation
    • Flattop: point 4
    • Squeeze: point 4 and triplets
  • Wire scans during ramp, squeeze and collision
  • Luminosity data
wire scanner calibration
Wire Scanner Calibration
  • Orbit bumps at 450 GeV and 4 TeV
  • Going from +3mm to -3mm in 1mm steps
    • Wire scanner

B1V, B2H and

B2V similar

  • Calibration OK
    • bump versus wire scanner response fully consistent at flattop and injection
    • The slopes are 1 within the measurement error
    • No energy dependence
k modulation @ 4tev
K-Modulation @ 4TeV
  • RQ6.R4
  • RQ7.R4
  • RQ5.L4
  • RQ5.R4

Beam 1

AFTER THE SQUEEZE

  • RQ5.R4
  • RQ5.L4
  • RQ6.L4

BEFORE THE SQUEEZE

AFTER THE SQUEEZE

BEFORE THE SQUEEZE

Beam 2

G. Trad

slide6

Before Squeeze

G. Trad

K-Modulation

@ 4TeV

Before Squeeze: After Squeeze:

k modulation @ 4 tev
K-Modulation @ 4 TeV

G. Trad

  • Noisy tune measurements specially at flattop with unsqueezed optics
  • Preliminary results to be compared
    • With last MD data (K-Modulation @ 450 GeV)
    • With the Beta-Beating measurements
emittance growth
Emittance Growth
  • Look at emittance growth during ramp
  • Calculate emittance from luminosity at collision
    • Compare with wire scan data
  • Emittance determined with measured betas at injection and flattop from Rogelio’s team, interpolation in between
  • Error bars indicate difference between in and out wire scan
emittance versus intensity loss
Emittance versus Intensity Loss
  • Results from MD II
    • intermediate collimator settings to not lose intensity
  • Still emittance shrinkage during ramp, but less pronounced than in last MD
  • Almost no intensity loss – not clear whether correlated to emittance decrease!
luminosity data
Luminosity Data
  • 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
  • Emittances from wire scans significantly smaller than emittances from luminosity (especially ATLAS)
  • Need to check with k-modulation betas
summary
Summary
  • Preliminary results so far…
  • Emittances measured by wire scanners decrease through the ramp.
    • …despite much reduced intensity loss
  • 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
emittance at ramp
Emittance at Ramp
  • Emittances grow until ~ 1/3 of Ramp, then decrease
  • Except for Beam 2 H
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