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Robust Alignment of the Inner Detector Alignment Meeting – 1 st June 2005 Florian Heinemann ATLAS Alignment Challenge Robust Alignment Code
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Uncertainties on module positions Richard Hawkings, CERN-PH/ATT, January 2005 µm RMS
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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
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Track based alignment Robust Alignment Gobal 2
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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
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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
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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
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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
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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
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Overlap residuals 1 st test version is running For single module overlaps: Need higher statistics → Use batch farm
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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)
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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
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Summary - Outlook Migration started Work together with Munich First code is running Aim: Barrel version running and tested in September Still lots to do!
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