Jitter Monitor

1
Jitter Monitor Overview and Status Report

• Glenn Christian, Alexander Kalinin
• 30 May 2005

2
Contents

• Jitter Monitor Hardware Overview
• Measurement procedure
• March 2005 data taking
• Status of Analysis
• Resolution studies
• Plan for current run

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Jitter Monitor Schematic
4
Jitter Monitor Hardware
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Measurement Procedure

• Synchronisation
• Sum and Difference signals must be aligned to 10
  ps
• Dedicated data run for each processor at each
  pick-up with large beam displacement to suppress
  common-mode
• Each processor will have a general delay value
  due to difference in cable lengths and intrinsic
  delay on board

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Measurement Procedure 2

• Time align signals using synchronisation delay
• Calculate position as
• Calibrate position using correctors and known
  displacements

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Overview of March 2005 data taking

• Four jitter monitor processors used at BPMs
  8,10,13 in ExtLine, and BPMs 26,27 in DR.
• Data taken during three shifts
• Single-bunch mode synchronisation data for
  8,13,26,27 and calibration for 26,27
• Multi-bunch synchronisation for bpm10,
  calibration for 8,10,13 and resolution
• Single-bunch mode 8,13 SB calibration. 26,27 to
  8,13 correlation studies varying y, y, E.
• Data taken with all quads off after QD6X.

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Resolution

• Assuming the BPM thermal noise to be small the
  resolution will be dominated by discretisation
  noise of scopes.
• 3 BPM method
• Use position measured in two BPMs to predict
  position in third BPM.
• Assuming noise of all three BPMs to be the same,
  resolution is determined by std of residuals
  divided by geometric factor.

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Position in Extraction Line
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Resolution
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Angle-angle correlation
With all quads off between three BPMs the
trajectory should form straight line!
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Resolution studies (cont)

• General increase in resolution as function of
  bunch number along train lack of angle-angle
  correlation suggest that residuals contain
  contribution from jitter.
• Can not be sure how the jitter propagates between
  BPMs. Therefore 3 BPM method can not be used for
  discretisation resolution.

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Plan for parasitic work this run

• Plan to measure resolution by hooking up two
  processors in series on one set of pick-ups.
  Method eliminates bunch jitter from the
  calculation leaving only dicretisation noise.
• By making measurements at different scope scales
  can also measure the resolution dependence on
  number of discretes

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Summary

• Jitter monitor analysis still in progress.
• Once present problems encountered with resolution
  are solved, there is still lots of interesting
  data to analyse from March.
• Plan to take data parasitically to measure the
  2-BPM resolution in this visit.