1. VERY PRELIMINARY SURVEY OF MAGNET AXES OF USS – FC – DSS 26 March 2015 V. Blackmore & J. Cobb Everything that follows must be regarded as very preliminary Mapping – finding the axes – has not been trivial –Several algorithms / fits –Independent codes & cross checks Very useful –FCs best understood Flip mode allows some sanity checks Some puzzles still remain –FC2 recently re-surveyed in MICE Hall »New measurements (1/2 hour ago) not digested yet Still work to do –SSs have had less attention Mess of survey files for DSS –Work in progress

2. Alignment of Bobbins FCs –Manufacturers aligned axes of bobbins to within 50 –100 microns of centres of PCD of bolt holes in flanges at each end of module Provides some cross check USS & DSS –Not known what was specified or done

3. Procedure Module and Mapper surveyed in same coordinate systems Analyse mapper data –Gives magnetic axis in Mapper Coordinates x – z and y – z projections –Apply survey corrections  axis in Module system (simple additions) Errors are ~ 0.1 – 0.2 mm in x, y for FCs –Unknown yet for USS, DSS but probably similar in mapper coords –Caveat Understanding the DSS survey Mapper was knocked at some point; resurveyed –Nightmarish

4. VERY PRELIMINARY Hot off the press The two views show where the magnetic axes of modules would be if simply bolted together: Upper: Plan Lower: Elevation 1.The FC is ~ 1mm out of spec. but hope re-survey will fix that 2.There are very large offsets in USS and, especially DSS 3.Bolt holes allow for maximum of 2mm movement in one direction (you choose).

5. FC Status MPB 5/20 April 2014 THE END