Transfer Line Studies

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Transfer Line Studies
James N. Bellinger University of
Wisconsin-Madison 12 December 2008
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Summary

• No Cocoa yet
• Hand fits show relative rotation among Endcap
  disks
• Can identify backwards DCOPS

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Description

• 6 Transfer lines at 60 degree intervals around
  the outside of the detector
• 12 DCOPS on each Transfer line
• 4 on each Endcap
• 4 on selected MABs
• 2 Lasers on each Transfer line
• Call them the Plus and Minus lasers
• 72 DCOPS in all, with 144 readings
• Oriented so the 1/3 CCD pair measure Rf, 2/4 pair
  measures radius

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Problems

• A few DCOPS were unreadable
• Sometimes LV to Barrel DCOPS was off
• Lasers were shadowed in places no signal
• Laser direction not always adjustable

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Layout
YB2
YB0
YB-0
YB-2
Laser
Laser
ME-4
ME4
ME3
ME2
ME1
ME-3
ME-1
ME12
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Cocoa Model of Transfer Lines

• Is not ready yet.

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Data Selection

• From CRAFT run
• Select interval with field at 3.8T in which laser
  directions dont drift much
• Select interval with field off ditto
• (CRAFT data taking was two runs would have been
  a single run if the power hadnt failed)
• Plot the distribution of mean values subject to
  quality cuts
• Background area lt300000 pixel x counts
• Signal areagt0 and lt500000
• Sigma gt39 pixels and lt 220
• Meangt0 pixels and lt 2048

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Endcap-only study

• For each magnetic field state
• For each Endcap, use the laser at that end
• For each Transfer line, use the 4 DCOPS
• Reorient the CCD information to match DCOPS
  mounting
• For each CCD, fit the means at the 4 DCOPS and
  find the residuals
• Average the residuals of opposite pairs of CCDs
• Interpret these residuals as displacements of the
  DCOPS and plot them

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Plus Endcap DCOPS displacements
Vectors plotted to show dX Ring diameter is not
relevant Largest vector has length given in the
title Vectors at center average of rest, to
estimate disk displacement
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Minus Endcap DCOPS displacements
ME-1 and ME-2 show relative rotation about .5
mrad ME-1 and ME-2 show relative dislocation
of about 3mm
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Change with field
Change in relative displacement with field is
mostly radial ME3 and ME2 move oppositely
(EXPECTED!)
The disk YE2 bends, and the DCOPS positions
are cantilevered
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Change of Raw Beam Positions
ME-3
ME-4
Difference between field on and off for Minus
endcap at each station, as a function of
position (f) around the disk. ME-4 next to
laser little change ME-3 about 3mm ME-2
about 3mm ME-1 about 8mm
ME-1
ME-2
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Connecting Across

• Select data from 16-August
• Not all profiles are usable
• For Transfer Line 1, only connect with Up/Down
  CCD data (Rf)
• Both lasers reach across for Line 1, so I can
  compare their results directly

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Example of Transfer Line Profiles
CCD0
CCD0 data reaches across, but CCD1 gets blocked
somewhere
CCD1
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DCOPS orientations
This one is odd data suggests other direction
DCOPS directions arent the same along a line
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Deviations from Linear Fit

• 10 Stations had data for Up/Down CCDs (not always
  both of the pair) for both laser beams
• Estimated laser tilt
• Averaged CCD values if both present
• Corrected for laser tilt if not
• Fit for each laser and plotted the deviations
  from the fits

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Oddity
RMS3.3mm
Difference is huge at this point. If I assume
the DCOPS is backwards, the points fit very
well.
RMS1.0mm
Difference in deviations found using Plus and
Minus laser fits
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Conclusions

• When the beam is unobstructed we can get useful
  information out of the system
• Once mounting variations are understood well
  have a better measure of the resolution of the
  system