1. Recent Results on TRT Alignment
Andrea Bocci (Duke Univesity)
Wouter Hulsbergen (CERN)
9/15/2006

2. Where we were The TRTAlignAlgs package performs:
Global TRT-SCT alignment
TRT module alignment
Here we concentrate on the local alignment of the TRT modules.
Two degree of freedom considered:
Module translation along x
Module rotation around its axis
The method actually converges after few iterations

3. Rotation multiply by a factor 500
Rotation Pattern
It has been shown also that the TRT modules present an interesting rotation pattern
Rotation multiply by a factor 500

4. Module Split
As a following step in understanding of the TRT module misalignment we spitted the residuals of each module in two, one for z>0 and the other for z<0 hits
In reality for cosmic data this was possible only for the top sector modules (bottom modules had only one side instrumented)
Using the alignment constants extracted from the whole-module residuals, we applied an extra iteration to the spitted modules
If the two modules sides are (mis)aligned in the same way this extra iteration should provide the same alignment constants of the whole module

5. Module Split: Results Module 6 Module 7 dx Layer Layer dphi Layer
Here the difference in dx and dphi are shown w.r.t the previous iteration
Yellow: Whole Barrel, Red: Left Side, Blue: Right Side
Module 6
Module 7 dx
Layer
Layer
dphi
Layer
Layer

6. Are we observing a module twist ??
Module Split: Results
Here it is how the rotation looks like (w.r.t. the whole module)
Only Top Sector
Dotted line is the whole module
Are we observing a module twist ??

7. Method Sensitivity
Before any conclusion we need to assess the sensitivity of our method
The error values we got are only statistical and they are known to be underestimated
As an alternative method to estimate our sensitivity we used two approaches:
We applied the alignment constant extracted from one run to another run (independent sample)
We applied our alignment procedure to a perfect aligned Monte Carlo sample
In the first case we assume that the misalignment of the detector didn’t change between the two runs and hence the constants from one run should be good for the other run
For the MC we assumed that it can reproduce fairly enough the data

8. Run Comparison: dx
We applied the constants from the 3007 run to the 3099 run

9. Run Comparison: dphi
We applied the constants from the 3007 run to the 3099 run

10. Nominal MC results: dx Module 6 - top Module 7 - top Module 6 - bottom
In this case we used two different files, one with low statistic and the other with x3 statistic. In this way we also can have a feeling of the event number impact on our results
Module 6 - top
Module 7 - top
Module 6 - bottom
Module 7 - bottom

11. Nominal MC results: dphi
In this case we used two different files, one with low statistic and the other with x3 statistic. In this way we also can have a feeling of the event number impact on our results
Module 6 - top
Module 7 - top
Module 6 - bottom
Module 7 - bottom

12. MC vs. Data
Is the misalignment of a perfect aligned detector real ??
We compared the data (run 3007) and MC (nominal) residuals
We found that for the bottom modules they agree fairly well, but for the top modules the MC have wider residual distribution
Bottom
Top
Are the not instrumented side of the bottom modules active in MC ?

13. Survey misalignment vs. Track misalignment
We were able to access the survey measurement made n SR1 about the SCT position w.r.t. TRT. We don’t have the details about these measurements were made, we needed to guess Z X

14. Survey misalignment vs. Track misalignment
We were able to access the survey measurement made n SR1 about the SCT position w.r.t. TRT. We don’t have the details about these measurements were made, we needed to guess Z Y

15. Survey misalignment vs. Track misalignmentZ Y

16. Survey misalignment vs. Track misalignment
Q: How these survey data reconcile with the global TRT-SCT alignment costants implemented in TRTAlignAlgs (based on cosmic data tracks) ??
A: Not totally trivial to compare the two measurements, the data driven numbers depend on tracks direction as well. After some trigonometry the formula two compare the two is:
(dx)` = dx – dy/tg w
Where (dx)’ is the track based displacement and dx,dy is the survey based ones. The tracks angle is w (~ rad)
Putting in the number we get:
(dx)` = and (dphi)` =
From TRTAlignAlgs:
(dx)` = and (dphi)` =

17. TRT Software

18. TRT Software

19. TRT Software

20. TRT Software

21. TRT Software