1. Robust Alignment of the Inner Detector Alignment Meeting – 1 st June 2005 Florian Heinemann ATLAS  Alignment Challenge  Robust Alignment  Code

2. Uncertainties on module positions Richard Hawkings, CERN-PH/ATT, January 2005 µm RMS

3. Alignment Challenge 5832 modules → 34992 DoF’s Don’t degrade intrinsic resolution > 20 % But know position only ~ 100 µm Get precision with software: At least ~ 10 µm For W mass ~ 1µm 6 DoF’s

4. Track based alignment Robust Alignment Gobal  2

5. Robust Alignment ס ס A B Mean of A – B ≈ 0 Idea: Use overlap residuals for determining relative module to module misalignment Overlap residual = outer hit residual – inner hit residual

6. Robust Alignment Mean of A – B ≈ Relative misalignment ס ס ס Idea: Use overlap residuals for determining relative module to module misalignment Overlap residual = outer hit residual – inner hit residual

7. Robust Alignment  Measure Rφ and z overlap residuals for each two overlaps  Use residuals also for barrel to barrel alignment  Danny Hindson: Developed software prototype for Pixel and SCT barrel Tested for inter-barrel module shifts in Rφ and z, but no rotations, no radius change Tested for barrel to barrel alignment Problems with sagitta distortions partly solved with E/p  Advantage: Simple, stable and covers most DoF  But: Like FSI and Global  2 might have problem to find simple modes  Need:  Migration to Athena  Further development like extension to endcap and sagitta removal RφRφ z New powerful classes available System of data handling changed Code must be invariant to further modifications Rewrite Code

8. Software Status  Develop in package /InDetAlignment/SiRobustAlign/SiRobustAlign-00-00-0*  Input: test.002928.romedig904.higgs120_tautau._000*.pool.root (Rome)  Reconstruction presently with xKalman  Use Trk::Track tracks from StoreGate  Classes used so far: class IToolSvc; class StoreGateSvc; class Identifier; class EventInfo; class AtlasDetectorID; class AlignSiModule; class AlignSiHit; namespace Trk { class Track; class TrackStateOnSurface; class INavigator; class IExtrapolator; class IPropagator; class RIO_OnTrack; class TrackParameters; } namespace InDetDD{ class SCT_DetectorManager; class PixelDetectorManager; } namespace AIDA { class IHistogram1D; } namespace SiRobustAlign { class HitOnModule; class RobustAlignAlg : public Algorithm { public: Own Algorithm } Track properties including hits Main algorithm and new objects Gives detector info

9. RobustAlignAlg  Loop over trackStateOnSurfaces() ->rioOnTrack()  Residuals, e.g Rφ = hit->localPosition().x() - trackParVector[Trk::locX] (local frame)  Mainly work on the rioOnTrack() level (ESD), but info like cluster size need prepRawData First code in CVS However, this is not what I want In contact with Edward Moyse Soon: Direct way to get global position implemented

10. Overlap residuals  1 st test version is running For single module overlaps: Need higher statistics → Use batch farm

11. Next steps  Test with misalignment  Solve management of histograms  Get local misalignment for every module  Get uncertainties  Perform iterating and refitting  Extend to endcaps Wait for Tool in InDetAlignDBTool (Richard)

12. Munich contribution  3D residual – distance of closest approach (DOCA)  Calculate local  2 – sum over all tracks  Calculate derivatives by moving modules  Minimise 1 st order approximation of  2  Go one step in the right direction  No knowledge about achievable precision yet DOCA Possible help for iteration and refitting

13. Summary - Outlook  Migration started  Work together with Munich  First code is running  Aim: Barrel version running and tested in September  Still lots to do!