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Recent Results on TRT Alignment

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

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Recent Results on TRT Alignment

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  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 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 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. 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 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 misalignment Z 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 (~ -1.92 rad) Putting in the number we get: (dx)` = -0.29 and (dphi)` = 0.000186 From TRTAlignAlgs: (dx)` = -0.29025 and (dphi)` = 0.000276

  17. TRT Software

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