Recent Results on TRT AlignmentRecent Results on TRT Alignment

Andrea BocciAndrea Bocci (Duke Univesity)

Wouter HulsbergenWouter Hulsbergen (CERN)

9/15/2006

Where we wereWhere 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

Rotation PatternRotation Pattern

It has been shown also that the TRT modules present an interesting rotation pattern

Rotation multiply by a factor 500

Module SplitModule 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

Module Split: ResultsModule 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

dx

dphi

Module 6 Module 7

Layer

Layer

Layer

Layer

Module Split: ResultsModule Split: Results

Here it is how the rotation looks like (w.r.t. the whole module)

Only Top SectorDotted line is the whole module

Are we observing a Are we observing a module twist ??module twist ??

Method Sensitivity 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

Run Comparison: dxRun Comparison: dx

We applied the constants from the 3007 run to the 3099 run

Run Comparison: dphiRun Comparison: dphi

We applied the constants from the 3007 run to the 3099 run

Nominal MC results: dxNominal 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

Nominal MC results: dphiNominal 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

MC vs. DataMC 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

Top Bottom

Are the not instrumented side of the bottom modules active in MC ?Are the not instrumented side of the bottom modules active in MC ?

Survey misalignment vs. Track misalignmentSurvey 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

X

Z

Survey misalignment vs. Track misalignmentSurvey 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

Y

Z

Survey misalignment vs. Track misalignmentSurvey misalignment vs. Track misalignment

Y

Z

Survey misalignment vs. Track misalignmentSurvey 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

TRT SoftwareTRT Software

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