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Pixel stand alone alignment status V. Karimäki, T. Lampén

Project meeting Helsinki 31.03.2009. Pixel stand alone alignment status V. Karimäki, T. Lampén. Outline. Recall the problem Simultaneous vertex and track fit vertex contraint (unknown position) beam spot constraint (average position known). Basics - recall.

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Pixel stand alone alignment status V. Karimäki, T. Lampén

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  1. Project meeting Helsinki 31.03.2009 Pixel stand alone alignment statusV. Karimäki, T. Lampén

  2. Outline • Recall the problem • Simultaneous vertex and track fit • vertex contraint (unknown position) • beam spot constraint (average position known)

  3. Basics - recall • Problem inPixel stand alone alignment: short tracks, curvature purely measured • Evoke the idea presented earlier by us: • take curvature from full tracker reconstruction • use then only Pixel hits for alignment • Feasibility of the idea was studied: Curvature precision requirements for Pixel alignment • So fixing curvatures for Pixel alignment ok

  4. Relevant formulas

  5. Outline of the algorithm • Full tracker reconstruction • Choose tracks for Pixel alignment • Fix curvatures obtained by full tracker fit • Use pure helix: • B (almost) uniform in Pixel region • material budget smallest in Pixel region • Vertex constraint (tracks from one point) • Seed the new residuals to the HIP algo

  6. Status of the work • “Toy” Monte Carlo ready to prove the concept: • Helix: circle in xy (VK), straight line in sz (TL) • Helix + VX constraint: (2+N)*(2+N) matrix Inversion (N = number of tracks) • Pull distributions fine • Start then implementation to the HIP alignment framework

  7. Pull distributions

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