Detector Alignment Activities

1. Detector Alignment Activities Evaluation of HIP CMS Software and Physics Project 22nd May 2006 T. Lampén

2. Overview SiBT • Alignment with tracks with HIP algorithm • Helsinki Silicon Beam Telescope • Cosmic Rack setup • CMS Pixel • Misalignment simulation of CMS • participated to sw development: tools and ready-made misalignment scenarios • Quality control of Tracker Outer Barrel (TOB)rod manufacturing • hands-on insight to misalignments Cosmic Rack CMS Pixel

3. Timeline of Alignment Activities 22.5.2006 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 SiBT Alignment Cosmic Rack Alignment Px alignment, CMS reconstruction sw Px alignment, stand-alone supporting activities CMS misalignments Rod measurements

4. Alignment with tracks – background • begun 1998: Silicon Beam Telescope (SiBT) • 2-parameter alignment of individual modules • Alignment algorithm developed further (and published) • all 3+3 parameters for individual modules • named as HIP algorithm (Hits and Impact Points) • Applied to • SiBT, several times • CMS Pixel 2002, standalone sw • CMS Pixel alignment, official sw (on-going) • Alignment of Cosmic Racks (on-going) • CMS TOB CRack (CERN) • FinnCRack (Helsinki) Cosmic Rack

5. Alignment with Tracks - status • A high-priority issue for start-up & long-term operation! • 3 Alignment algorithms studied within CMS (see also Physics TDR 1): • HIP algorithm, Helsinki (CMS-Note 2006/018) • Millepede, Hamburg (CMS Note 2006/011) • Kalman filter, Vienna (CMS Note 2006/022) • HIP algorithm most robust and computationally light,a promising candidate for Pixel alignment,(no optical alignment system for Pixel) • HIP algorithm currently most developed algorithm • 3 CMS Notes in 2005/2006, Physics TDR 1 contribution, active reporting in conferences

6. Alignment with Tracks – future plans • Currently studying Pixel alignment with HIP algorithm with • minimum bias events • cosmics, beam halo events • J/Psi events • muons from Z,W • Production of min. bias events with computer cluster in Helsinki • Goal in near future: refine alignment strategy for pixel • Goal in longer term: active part in track-based alignment of CMS Tracker before and during operation • Co-operation with HIP Tracker project: FinnCRack • Manpower: VK + TL, summer students

7. Alignment with tracks – example of HIP algorithm with min. bias events Misalignments in local coordinates of all individual pixel moduls Loca ideal strip detector used 100k m.b. events individual pixel modules aligned with HIP algorithm 20 iterations converges to level of few tens of um encouraging results u v w misalignment In global coordinates y z x misalignment iteration iteration iteration

8. Example of Cosmic Rack alignment(Physics TDR) testbeam data, alignment of 2 parameters A particular module translation rotation Track Chi^2 convergence

9. Simulation of Misalignments • To study alignment algorithm, initial misalignments need to be simulated • Same tools can be used to introduce estimated misalignments • We have in 2004-2005 • implemented tools for Pixel misalignment in ORCA software • participated actively in development of the Misalignment Scenarios of the CMS (CMS Note 2006/008) • First data scenario (after 100 pb-1) • Long term scenario (after 1 fb-1) • A natural introduction to alignment studies!

10. TOB Rod Quality Control Measurement Jig Measurement Probe • All 750 Tracker Outer Barrel support rods manufactured and measured in Helsinki • Measurements serve as quality control,but also provide initial alignment parameters • This work also supports well alignment studies and gives realistic insight to actual misalignments! Translation of a module Rotation of a module RMS 40 um RMS 0.2 mrad Limits for good / acceptable values, limits for rejection out of plot range

11. Summary and Plans • Main activity: software alignment by tracks with HIP algorithm, high-priority issue for CMS • HIP algorithm most developed of the 3 algorithms within CMS,reported in Physics TDR 1 • Goals: • 2006: optimize alignment strategy for pixel with HIP algorithm • 2007: participate actively to initial alignment of CMS Tracker • 2008: long-term alignment of CMS Tracker • Work for one grad. student, tasks for summer students • Proceeding with good momentum: 3 CMS Notes in January 2006, conference talks (CHEP06), etc.