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Overview of ATLAS Alignment at Oxford

Overview of ATLAS Alignment at Oxford. Aims and emphasis of meetings Overview of alignment activities Done and to do Suggestions for discussion topics Web pages. Aims of meeting:. Coordinate alignment software effort in Oxford.

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Overview of ATLAS Alignment at Oxford

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  1. Overview of ATLAS Alignment at Oxford Aims and emphasis of meetings Overview of alignment activities Done and to do Suggestions for discussion topics Web pages

  2. Aims of meeting: • Coordinate alignment software effort in Oxford. • Emphasis is on alignment software, rather than hardware issues. • Provide an overview of the different alignment activities: • within Oxford and • elsewhere (RAL, CERN, Munich…) • Encourage interaction between activities. • Help develop a coherent alignment strategy! • Set up internal project milestones. • Internal meeting to help us contribute to CERN meetings. Oxford ATLAS Alignment Meeting

  3. Alignment Activities+ active people in Oxford (+elsewhere) • Global Chi Squared minimisation. • Pawel, Müge. (Adlène H, Stephen H. at RAL) • Robust Alignment • [Danny], Florian. (+Munich group, Richard Hawkings) • Runtime alignment system (FSI) • {Paul}, Stephen, Takanori, Pawel, (Sandra), Richard... • X-ray survey • Nick, Jim, Richard. • B-field • Jonathan (Steve Snow, John Hart) Oxford ATLAS Alignment Meeting

  4. Global Chi2 Minimisation • Aims to fit all module coordinates at once by minimising a global chi2 of track residuals. • Need ~24 hours track data to reach around 1micron statistical precision (assuming only RPhi movements). • Computing intensive approach – Beowulf cluster. • Sensitive to high spatial frequency eigenmodes on time scales of ~24hrs. • Status: • Prototype code currently being modified for Athena framework. • “Alignment challenge” in Summer 2005. Oxford ATLAS Alignment Meeting

  5. Robust Alignment • Iterative procedure to make alignment in small steps using track residuals and overlaps. • Align modules in rings, staves, barrels… • Intuitive approach with more understandable output. • Not sensitive to some deformations (sagitta). • Status: • Barrel code developed by Danny Hindson. • Florian rewritting Danny’s algorithm in Athena, with the aim of extending to the end-cap regions. • Munich involved in similar approach. Oxford ATLAS Alignment Meeting

  6. Runtime Alignment System (FSI) • Grid of 842 distance measurements that monitor shape of SCT. • FSI Grid can be measured upto every few minutes, allowing short time scale distortions to be detected and corrected. • Sensitive to low spatial frequency eigenmodes of tracker distortion. • Complements track based alignment methods to improve overall precision. • Will help us understand systematics. • Status: • On-detector Hardware nearing completion (June/July 2005). • Need to write new control software to commission the lasers, before shipping the off-detector system to CERN in January 2006. • Several large software issues need to be resolved - see later slide. Oxford ATLAS Alignment Meeting

  7. X-ray survey • Planned to determine SCT module coordinates to high precision before installation. Oxford ATLAS Alignment Meeting

  8. Large Software Tasks Ahead • FSI: • control and data acquisition software. • raw data analysis and length extraction software. (requires extraction of DCS temperature information). • Grid reconstruction software final code. • Module interpolation software/ integration of FSI with track based alignment. • Global Chi Squared final code. • Robust alignment final code. • X-ray software? • Incorporation of software into CERN Athena framework. • We need to define how the alignment software areas interact with each other and with the CERN database. Oxford ATLAS Alignment Meeting

  9. Discussion Topics • When will the code be needed for each activity? • How to integrate FSI with robust/global chi2, track based alignment? • Plans for X-ray software? How do we calibrate FSI without an X-ray survey. • How to distinguish B-field effects from track based alignment. • Data storage – which alignment data will we store, where and for how long? • Need to work in a common coordinate system. • Perhaps nominate one person from each work area to summarise their expections for every part of the final system software and then discuss the differences….?! Oxford ATLAS Alignment Meeting

  10. Alignment web pages • Webpages currently scattered and/or need updating: • Very old (<2000) web pages on alignment: ESPI, FSI, X-ray. /~altlas/alignment/ • Paul pages on Runtime alignment system under /~atlas/ • Pawel’s CERN page on GlobalChi2 prototype • Two pages on Robust alignment and FSI Module Interpolation, written by Danny, under ~/hindson/ • Suggest reorganisation by setting up a new account “idalign” on pplxgen, accessible to all Oxford aligners, under which people can move/create new web pages. • Create new Oxford alignment homepage under /~idalign/, linked to the Oxford /~atlas/ page. • Then for each alignment activity create a new working area: /~idalign/fsi/ , /~idalign/robust/ etc… Oxford ATLAS Alignment Meeting

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