1. Comparing Laser Fit to Barrel Fit University of Wisconsin-Madison
James N. Bellinger
University of Wisconsin-Madison
12-August-2011
V1.1
James N Bellinger UW Madison

2. Validation Exercise Fix Transfer Lines using positions at MAB3
Predict DCOPS centers all along the lines
Compare my prediction with Barrel inner MAB DCOPS centers
Examine predictions of ME station positions for sanity
Two possible sources for MAB3
Barrel fit (more likely to be self-consistent w/ MAB1?)
Link fit (use z-bar fit)
How are these related?
24 February 2019
James N Bellinger UW Madison

3. Description of Part 1
Study “radial” direction for DCOPS: insensitive to rotations, and “tangential” directions which are
Centers change radius with field, but should be symmetric Plus/Minus
ABANDON THIS ASSUMPTION! Rely on MAB3
Given PG MAB calibration, find DCOPS center wrt MAB center
Use the Barrel fit for MAB center and orientation to calculate the DCOPS center position for all MABs
Anchor my laser line fits using the Barrel MAB3 DCOPS Centers from 4
Calculate “radial” positions for all other DCOPS
Compare MAB1 Barrel fit position w/ my prediction
My fit does not include MAB1 Barrel information: independent
24 February 2019
James N Bellinger UW Madison

4. Schematic of my fit Calculate relative offsets and
add to the line through MAB3
points
Compare w/ Barrel fit
Fixed relative offset=0
Barrel fit radius used
Calculation uses
average profile
position at center
of DCOPS—no tilt
MAB+3
MAB-3
Given profile centers for both lasers, fit for laser lines and DCOPS offsets
24 February 2019
James N Bellinger UW Madison

5. Predicted radius - Barrel radius
0.56mm systematic shift
RMS=0.27mm!
Very tight distribution
Why the offset?
24 February 2019
James N Bellinger UW Madison

6. My Predicted – Barrel Tangential Fit for MAB1
Again an offset;
1.2mm= 2x the radial
RMS is better than
earlier analyses, but
not as good as radial
Rotation about CMS-Z?
24 February 2019
James N Bellinger UW Madison

7. My Predicted – Barrel Tangential Fit details
Difference of
differences is
almost the same
at each line,
(modulo sign
change)!
Strongly suggests
calculation
artifact somewhere
24 February 2019
James N Bellinger UW Madison

8. Part 2 Compare the predicted DCOPS positions on the different stations
Look for bulk shifts corresponding to disk movement
Look for bending in YE+2 and YE-2
Should be similar
Look for Rphi agreement ME3 and ME2
Should be that same
Need to include PG offsets wrt the ideal for transfer plates to do this correctly—not done yet
24 February 2019
James N Bellinger UW Madison

9. Predicted radius - Barrel radius
MAB+1
MAB+1 and
MAB-1 have
consistent
mean and RMS
(MAB+1/Line5
MAB did not
read out)
MAB-1
24 February 2019
James N Bellinger UW Madison

10. ME+4 – ME-4 Coords VS Phi ME+4 – ME-4 Vertical (radius) and Horizontal
(tangent)
Clear pattern:
YE+3 is shifted
wrt YE-3 by
O(5.5mm)
(Transfer Plate
mounting
corrections NOT
included)
24 February 2019
James N Bellinger UW Madison

11. YE+3 vs YE+2 ME+4 vs ME+2 Very clearly YE+3 is shifted wrt YE+2 by
O(5.1mm)
24 February 2019
James N Bellinger UW Madison

12. Consistency at/between YE+2 YE-2
Fair agreement
YE2 bending: Expect
ME3-ME2 radius O(-4): OK
variation in horiz O(.2): not
dR=-5.7±1.3
dRPhi=-1.2±.9
dR=-3.9±.6
dRPhi=-1.5±.4
PG variation in mounting O(1.5)
24 February 2019
James N Bellinger UW Madison

13. Repeat Using Link for MAB3
Still use barrel for MAB1
Some MAB rotations are default values
The fit is exactly the same—the only thing that changes are the points I use to anchor the DCOPS line. This uses the Link fit to MAB3 instead of the Barrel fit.
24 February 2019
James N Bellinger UW Madison

14. Link-based MAB3: MAB1 Radial Differences
Line 4 looks bad.
If I omit it, the
mean =0.47
RMS =0.71
Compare w/slide 5
mean =0.56
RMS =0.27
Consistent
Remember: I use
defaults for some
Link MAB params
2/24/2019
James N Bellinger UW Madison

15. Using Link Data to fix Prediction Line: Horizontal coordinates
Looks
worse:
See Slide 6
Here:
mean=-1.80
RMS=1.27
Before:
mean=-1.22
RMS=0.71
Consistent
24 February 2019
James N Bellinger UW Madison

16. Looking for Artifacts in Link-fixed Tangential Predictions
Line 6 is
out of line
with the rest.
Most show
about 1mm
between
residuals, as
before—but
with a new
sign pattern.
See slide 7
24 February 2019
James N Bellinger UW Madison

17. Link-fixed Tangential Predictions – Barrel, no Line 6
Without 6,
distribution
tighter, offset
smaller.
Compare
w/ Slide 15, 6
Here (Link cut):
-1.26±0.58
Link uncut (15)
-1.8±1.27
Slide 6 (barrel):
-1.22±0.71
24 February 2019
James N Bellinger UW Madison

18. Tentative Conclusions
Using MAB3 as fixed points validates the Transfer Line fit at the MAB1 positions at the .7mm RMS level in Rphi and .27mm in radius
Link-based MAB3 can be as good as Barrel- based MAB3, perhaps better—but bad measurements can throw us off
We see systematic offsets from the Transfer Line prediction to the Barrel measurements, whether we fix the MAB3 using Barrel or Link
24 February 2019
James N Bellinger UW Madison

19. Not understood yet
Why is there a radial offset from the Barrel DCOPS prediction to the Transfer Line prediction? (The precision looks good)
Why is there a Rphi offset from the Barrel DCOPS prediction to the Transfer Line prediction? (Precision looks fair)
What combination of Link and Barrel MAB3 measurements is best?
24 February 2019
James N Bellinger UW Madison

20. To Be Done
Calculate Transfer Plate PG deviations from ideal in these coordinates and apply to the disk shift/rotation study
Explore
What might cause a systematic offset in MAB1
What might cause the differences of deviations to cluster (slide 7, 16)
Providing Transfer Line fit as additional constraint to Barrel fit
Select the correct MAB3 fits to use as input
Joint fit to MAB3 and MAB1?
Estimate what the error will be in predicting Transfer Plate X/Y positions
2/24/2019
James N Bellinger UW Madison

21. BACKUP
24 February 2019
James N Bellinger UW Madison

22. Calculation
I use a Pari/gp script, interpreted by the gp program. Not COCOA
I know what it is doing
Chi-squared calculation rather than fit
Arbitrary precision in matrix inversions
Generates relative offsets
Fast.
I used this for producing the position vs time plots to determine if a MAB fall had caused blockage or whether the floor was sagging. Processing a thousand events took hours—Cocoa would have spent days at it.
24 February 2019
James N Bellinger UW Madison

23. Data Event from 10-June Barrel event 3981
Almost all Transfer Line stations reproducible!
Barrel event 3981
MAB+1/9 does not read out; no position fit
Calculations done using tools shown in
24 February 2019
James N Bellinger UW Madison

24. Notes
Difference between DCOPS center radius and the local “Vertical” coordinate is at most 12 microns, so I don’t worry about it
The local DCOPS coordinate center is taken at the ideal position
Positive “Horizontal” coordinate is in the direction of positive phi
24 February 2019
James N Bellinger UW Madison