1. S.Ecklund, C.LeCocq, R.Pushor, R.Ruland, A.Seryi, Z.Wolf
PEP-II IR2 alignment
S.Ecklund, C.LeCocq, R.Pushor, R.Ruland, A.Seryi, Z.Wolf

2. Event flow Motivations
IR orbit correctors show correlation with current – IR magnets move?
Spring 2003 => tiltmeters installed on IR quads observe motion correlated with current
SR heating vacuum chamber => expansion => 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 => 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.

3. BINP SLAC sect.10
BINP 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

4. Left A
Backward
<= e+
Stretched wire. Sensors.
Hydrostatic sensors
Tiltmeters

5. Right B
Forward
<= e+
Laser tracker
Tiltmeters
Hydrostatic sensors

6. Left side.
Stretched wire system. Q5 Q4
Hydro sensors

7. Right side.
Targets
Laser tracker Q5 Q4
Hydro sensors on the raft.
Tiltmeters

8. IR magnet motion – “hydro” data The 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 => day of 2003.

9. 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

10. Left
Right
Raw data
Left side motion is caused primarily by LER– whose SR shines onto the left side
Left
Right
Correlation with LER current easier to see in the moments of different behavior of LER and HER currents

11. 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

12. 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.

13. 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.

14. Left raft motion model details 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.

15. Left IR magnet motion model
AVI
GIF

16. 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? …