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

2. Summary
No Cocoa yet
Hand fits show relative rotation among Endcap disks
Can identify backwards DCOPS
James N. Bellinger 12-December-2008

3. 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 Rφ, 2/4 pair measures radius
James N. Bellinger 12-December-2008

4. 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
James N. Bellinger 12-December-2008

5. Layout YB-2 YB-0 YB+0 YB+2 Laser Laser ME-4 ME-3 ME-1 ME+1 ME+2 ME+3
James N. Bellinger 12-December-2008

6. Cocoa Model of Transfer Lines
Is not ready yet.
James N. Bellinger 12-December-2008

7. Data Selection From CRAFT run
Select interval with field at 3.8T in which laser directions don’t drift much
Select interval with field off ditto
(CRAFT data taking was two runs: would have been a single run if the power hadn’t failed)
Plot the distribution of mean values subject to quality cuts
Background area < pixel x counts
Signal area>0 and <500000
Sigma >39 pixels and < 220
Mean>0 pixels and < 2048
James N. Bellinger 12-December-2008

8. 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
James N. Bellinger 12-December-2008

9. 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
James N. Bellinger 12-December-2008

10. 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
James N. Bellinger 12-December-2008

11. Change with field Change in relative displacement with field is mostly
radial
ME+3 and ME+2
move oppositely
(EXPECTED!)
The disk YE+2 bends, and the DCOPS
positions are cantilevered
James N. Bellinger 12-December-2008

12. Change of Raw Beam Positions
ME-4
ME-3
Difference between
field on and off for
Minus endcap at each
station, as a function of
position (φ) around the
disk.
ME-4 next to laser: little
change
ME-3: about 3mm
ME-2: about 3mm
ME-1: about 8mm
ME-2
ME-1
James N. Bellinger 12-December-2008

13. Connecting Across Select data from 16-August
Not all profiles are usable
For Transfer Line 1, only connect with Up/Down CCD data (Rφ)
Both lasers reach across for Line 1, so I can compare their results directly
James N. Bellinger 12-December-2008

14. Example of Transfer Line Profiles
CCD0
CCD0 data reaches across, but
CCD1 gets blocked somewhere
CCD1
James N. Bellinger 12-December-2008

15. DCOPS orientations This one is odd: DCOPS directions data suggests
other direction
DCOPS directions
aren’t the same
along a line
James N. Bellinger 12-December-2008

16. 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
James N. Bellinger 12-December-2008

17. Oddity RMS=3.3mm Difference is huge at this point. If I assume the
DCOPS is
backwards, the
points fit very
well.
RMS=1.0mm
Difference in
deviations found
using Plus and
Minus laser fits
James N. Bellinger 12-December-2008

18. Conclusions
When the beam is unobstructed we can get useful information out of the system
Once mounting variations are understood we’ll have a better measure of the resolution of the system
James N. Bellinger 12-December-2008