PEPII IR2 alignment

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PEP-II IR2 alignment

• S.Ecklund, C.LeCocq, R.Pushor, R.Ruland, A.Seryi,
  Z.Wolf

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Event flow

• Motivations
• IR orbit correctors show correlation with current
  IR magnets move?
• Spring 2003 gt tiltmeters installed on IR quads
  observe motion correlated with current
• SR heating vacuum chamber gt expansion gt push
  magnets
• August 2003 decided to install new systems in
  IR
• Hydrostatic level system
• Stretched wire system
• Laser tracker system
• This talk
• Data from 3 systems gt reconstruction of IR
  magnet motion
• Next
• Orbit motion modeling, optimization of orbit
  correction or feedforward. Possibly, cure the
  cause of motion

Consider only vertical motion. Horizontal data,
and data from laser tracker are being analyzed
and are not discussed in this talk.
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BINP HLS _at_ SLAC sect.10
BINP HLS _at_ FNAL MI8
Hydrostatic system developed by BINP for slow
ground motion characterization for NLC joint
study by BINP, FNAL, SLAC
A. Chupyra, A. Erokhin, M. Kondaurov, A.
Medvedko, V. Parkhomchuk, E. Shubin, S.
Singatulin, Budker INP J. Lach, D. Plant, V.
Shiltsev, J. Volk, Fermilab R. Ruland, A.
Seryi, SLAC
Stretched wire systems developed for LCLS. Both
HLS and wire system are foreseen to be used at
LCLS
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Left A Backward lt e
Stretched wire. Sensors.
Hydrostatic sensors
Tiltmeters
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Right B Forward lt e
Laser tracker
Tiltmeters
Hydrostatic sensors
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Left side.
Stretched wire system.
Q5
Q4
Hydro sensors
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Right side.
Targets
Laser tracker
Q5
Q4
Hydro sensors on the raft.
Tiltmeters
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IR magnet motion hydro dataThe left raft
motion is correlated with current(s), but not
much the right raft. Slope is changing more
significantly than the center of Q5 position.
IR Motion expressed as a vertical slope (pitch)
and position of the raft Slope positive slope
end of raft closer to IP lifts up. Raft position
is recalculated to the center of Q5 quad
(positive position means the raft is
higher). Horizontal axis gt day of 2003.
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Left side moves significantly more than the right
one, the motion is correlated with current
(mostly LER), is observed by hydro, wire and
tiltmeter systems, and correlates with IR orbit
feedback signals
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Left side motion is caused primarily by LER
whose SR shines onto the left side
Correlation with LER current easier to see in the
moments of different behavior of LER and HER
currents
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Reconstruction of IR motion

• Left side moves most
• Were lucky to install wire on the left side!
• Hydro system on the raft, wire and titmeters on
  magnets allow to reconstruct motion of magnets
• Is there only common pitch of the raft and no
  magnet motion relative to the raft?
• Considered and rejected as unsupported by data
• Is there transverse flexibility between Q2 and Q1
  that would affect wire data?
• Considered and rejected. Q2-Q1 is rigid
  transversely
• Shown below is a preliminary but consistent model
  of IR magnet motion

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Left raft IR magnet motion model
Model on top of hydro data (motion of raft as a
whole) add relative motion to be consistent with
wire and tiltmeters.
Example of magnet position for two extremes. The
raft pitch change by about 30 mrad, the magnet
position change by about 120 mm.
Most of deformation occur near Q2.
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Left raft motion model details of the fit to wire
data
Measured wire data
Modeled wire data
Model use common pitch of the left raft,
relative on raft motion, dependent on the common
pitch, to predict and make best fit to the
stretched wire data.
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Left raft motion modeldetails of the fit to
tiltmeter data
Measured tiltmeter data
Modeled tiltmeter data
Model use common pitch of the left raft,
relative on raft motion, dependent on the common
pitch, to predict and make best fit to the
tiltmeters data.
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Left IR magnet motion model
AVI
GIF
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Summary and next steps

• Installation of new alignment monitoring systems
  in IR-2 allowed to determine details of IR magnet
  motion
• Most of the fast (current-correlated) motion is
  on the left raft, due to LER SR, supposedly
  heating chamber near Q2
• Next step is orbit modeling and optimization of
  orbit correction and location of correctors.
  Possibly, with use of feedforward from alignment
  systems.
• Can this motion be cured?
• Re-steer orbit? (but there are many restrictions
  on orbit position)
• Mechanical design modification?