ST Alignment Validation M. Needham EPFL

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