1 / 30

ST Alignment Validation M. Needham EPFL

ST Alignment Validation M. Needham EPFL. Introduction. Detailed comparision of alignment databases October TED Overlaps: magnet on/ magnet off alignment Residuals November TED/ Beam off: magnet on/off alignment Residuals Long tracks magnet on: magnet on/off alignment IT Error tuning.

gene
Télécharger la présentation

ST Alignment Validation M. Needham EPFL

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ST Alignment Validation M. Needham EPFL

  2. Introduction Detailed comparision of alignment databases • October TED Overlaps: magnet on/ magnet off alignment • Residuals November TED/ Beam off: magnet on/off alignment • Residuals Long tracks magnet on: magnet on/off alignment • IT Error tuning Definitions + Databases: Magnet off: head-20100119 Magnet on: slice VeloOTTxTyModulesTxITTxTyRzTTModulesTxRz20100119.db magnet on++: magnet on + IT ladder alignment TxRz (with health warning) VeloOTTxTyModulesTxITTxTyRzLaddersTxRzTTModulesTxRz20100122.db

  3. Introduction Datasets: Magnet off: November TED, all Collision data with magnet off (including data with VELO moving) Magnet on: 63801, 63806, 63807, 63807, 63809, 63811, 63815, 63849 Magnet on selection cuts The ST selection: p > 6 GeV, 2/dof < 7

  4. Overlaps • Take Wouters database, transform to October TED and look at overlaps • Pros: Large high quality dataset that is well understood • Cons: October to December is a long time, IT + OT opened in October • Transformation October- November • Based on studies November TED • ‘pre-alignment’ in x only • Quality: dominated by systematics • Uncertainty: 50 microns ?

  5. Overlaps Overlaps in y decrease with z (beampipe hole bigger) T1: 19 mm T2: 12 mm T3: 5 mm Survey + correction for OT closing, box Alignment changes by ~ mm 1 mm Top A-Side C-Side IT3 5 mm 1 mm Bottom Other stations similar shifts 3 mm No physical overlap IT3C and IT3 Bottom

  6. A-Side Overlaps T1 T2 T3 B1 B2

  7. A-Side Overlaps

  8. C-Side Overlaps T1 T2 T3 Bias’s : 100- 200 micron level Better than anything we saw before…. Large biases but comparing October TED with December beam running and including constrainsts from VELO + OT B1

  9. C-Side Overlaps

  10. Overlap Summary • Magnet off data has biases of 200 microns in TED overlaps • Magnet on data has larger biases • But the movements are all at the 200 micron level [apart from Top T1] compared to magnet off • Constants are not so inconsistant magnet off/on • Pick one false minimum magnet off, another magnet on ?

  11. x Residuals Test Look at residuals in T2 • Dataset: November TED + magnet off • Databases: magnet on , magnet off T1 T2 T3 dx Differences magnet on/off at 100 micron level

  12. Residual Biases: Tracks Magnet-off data Magnet off alignment IT3 Bias @ 15 micron level IT2 IT1 A C Magnet-off data Magnet on alignment Bias @ 18 micron level

  13. Residual Biases: Tracks Magnet-off data Magnet on++ alignment RMS 85 m But this database is good for magnet on Magnet++ Magnet off Unbiased residual also degrades

  14. Residual Biases: Tracks Magnet-on data Magnet on alignment RMS 62 m Magnet-on data Magnet off alignment RMS 64 m

  15. Residual Biases: Tracks Magnet-on data Magnet on++ alignment RMS 15 m • Looks good and unbiased residual width improves by ~ 30 % • But this database is very bad for magnet off Magnet Magnet++ Unbiased residual

  16. Future Strategy • Finding the correct minimum is not trivial • Is there a real difference magnet off/on ? Get back to what we did on the MC, what we learnt was good with TED • Tune clusters errors [next slide] • Combining datasets [Wouter] • Track selection • Evolving cut and strong isolation criteria as in TED/MC studies • Momentum cut

  17. IT Error Tuning As in the TED, tune unbiased residuals for 1, 2, 3 ,4 strip clusters • Reasonable track selection: 2/dof < 7, p > 20 GeV • Assume 1 strip has a binary contribution • Unfolding this gives the misalignment / multiple scattering • Unfold this from the 2,3,4 cluster unbiased residual itClusterPosition = STOfflinePosition('ToolSvc.ITClusterPosition') itClusterPosition.ErrorVec = [0.28, 0.22, 0.35. 0.35] itClusterPosition.APE = 0.1 Early data tune:

  18. Summary • Getting the IT boxes inter-aligned is tough • Best database: good to 100 micron • Databases with magnet off/on differ • Differences @ the level of 100 -200 micron • But general trend is reasonably same ? • Magnet++ is different • Fixes magnet on by LARGE movements of ladders at price of worse magnet off

  19. Backup

  20. Go to TT Project to TT C-Side A-Side Better than Anything I have seen

  21. Go to TT Compare residuals extrapolating IT tracks to TT in TED + beam data Again discrepancies at the level of hundreds of microns Can partially be explained by different illumination [at least in Bottom case]

  22. Go to TT Propagate IT generic tracks to TT TED data It’s a rotation -5 mrad in Local frame Beam smaller y ] Examine the bad Guy in TTaX

  23. Go to TT x TED data TTaX TTaU Columns: TTa 7, 8, 9 TTb 8, 9, 10 TTbV Bad luck TTbX

  24. Go to TT • Bottom is consistant with Velo-TT studies of C. Salzmann • Very good cross-check ! • Top: Seems to be global offset. Coming from IT alignment ? • Subtracting offset my results consistant with C. Salzmann

  25. Comments • Inner Tracker consists of four loosely coupled systems • Lightweight frames+ boxes: twisting + distortions (ie rotations) important • Inter-alignment is a challenge: seen already June TED • Clear we did not take enough magnet off data (especially with Velo not moving) • But on the otherhand, we have many good things • A reasonable survey • Varied track sample: beam-gas, collisions, halo tracks, …. • Can use November TED simulataneously • Easy to use large October TED as cross-check (good to see IT overlaps)

  26. Comments • Thinking ahead… • Many of these advantages we lose if the detector is opened • OT is already opened. Movements of IT at 50 micron level

  27. Comments Ensure complementary + cross-checks @ same level as 2009 • Survey: what survey is needed, what is possible ? • TED data: ~ 50 shots to allow pre-alignment/cross-checks • Similar mix of beam-gas as 2009 ? Improve on 2009 • Larger sample with magnet off (100k ?) to see IT overlaps clearly • Anything else ? in TAE mode beam2 gas, displaced bunch collisions… • Magnet off: give me the hits of particles from anywhere I will give you the tracks

  28. October TED presented in December

  29. October TED presented in December

  30. Residual Biases: Tracks T-tracks Magnet-on data Magnet on alignment RMS 41 m  ~ 18 m Magnet-on data Magnet on alignment RMS 42 m  ~ 21 m

More Related