LiCAS Simulation

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LiCAS Simulation
Catherine LeCocq SLAC 04/05/07

• Based on
• Simulation of the LiCAS survey system for the ILC
• by
• G. Grzelak, A. Reichold, J. Dale, M. Dawson,
  J. Green, Y. Han, M. Jones, G. Moss, B.
  Ottewell, R. Wastie, D. Kamptner, J.
  Prenting, M. Schlosser
• University of Warsaw, University of Oxford,
  DESY, Hamburg
• Presented at the
• 9th INTERNATIONAL WORKSHOP ON ACCELERATOR
  ALIGNMENT, IWAA-2006
• Stanford Linear Accelerator Center, September
  25-29, 2006.

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LiCAS Overview

• LiCAS Instrumentation
• One laser line per train 4 CCD cameras per car
• Internal FSI 6 laser lines per train, 6
  retro-reflectors per car
• One clinometer per car
• External FSI 6 laser lines per car shooting to
  wall marker

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Methodology

• Start with the 3 graphs shown in Figure 4 of the
  paper TH007 presented at IWAA06
• Build a geometrical model
• Compare to the SIMULGEO results for the wall
  markers, presented in Figure 3
• Compare to the Random Walk Model presented in
  paragraph 3.1

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Single Train Cars Sigma

• Train Coordinate System
• Z axis Internal FSI with Car 0 as origin
• Internal FSI gives Z of following cars
• The clinometer on the car gives RZ
• The 4 CCDs in the car give X and Y of the car as
  well as RX and RY

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Single Train Markers Sigma

• Train Coordinate System to Car Coordinate System

• (u,v,w) are the coordinates of the marker in the
  car coordinate system. They can been obtained
  from the 6 external FSI measurements of the car.

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Single Train Markers Sigma

• Because car 0 is the origin of the train
  coordinate system, the coordinates of marker 0
  are simply the derived observations (u,v,w).
  Using the appropriate graph gives

• First approach, no correlation between (u,v,w).
• The sigma on the v measurement is very close to
  the value obtained by calculating the average of
  6 FSI measurements at 1µm (0.41 vs 0.45)

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25 Markers MATLAB Simulation
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135 Markers MATLAB Simulation
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Where To Go From Here

• Confirm the internal geometry of the train and
  the derived a-priori standard deviations.
• Obtain a detailed description of the external FSI
  system to complete the error model for the
  derived observations (u,v,w).
• Introduce systematic errors in the external FSI
  system for each car of the train.

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• IWAA Paper Extracts

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Schematic layout of the LSM CCDs