1. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 1 SURVEY FOR VELO INSTALLATION 1.SURVEY AT GROUND FLOOR - FIDUCIALISATION 2.SURVEY FOR INSTALLATION IN THE CAVERN LHCb – VELO INTEGRATION – January 17th, 2006

2. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 2 SURVEY FOR VELO – GENERAL INFORMATION “… estimation of the help we will need from you. (a) Position complete VELO unit (stand+vacuum vessel+center frame) with respect to nominal LHC collision axis/plane. (b) Check position of dummy detector frames inserted in place or real detector halves) with respect to easily visible marks on the centre frame … The VELO alignment requirements are …: 0.5 mm for all x, y and z, about 0.1 mrad for the polar angle of the dummy frames. Note: since the detector halves can be moved on-line and remotely by +/- 5 mm in x and y, the critical alignment constraints is really on the polar angle. ” Extract from e-mails from Massimiliano Ferro-Luzzi – Mar 03 / Feb 05 Which coord system? 0.5 mm at 1 sigma ? With respect to ? 1 sigma ?

3. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 3 SURVEY AT GROUND FLOOR “ … Dummy detector frames are inserted in the receiving structure where the detector halves must be installed. These dummy frames are provided with 5 holes: …. Depending on the dimensions of the 3D measuring machine at NIKHEF, a number of measurements will be done in Amsterdam on the center frame and on the dummy frames. What cannot be done in Amsterdam will be done at CERN (possibly by photogrammetry, at IP8 or off-site, depending on the survey group). Alignment with the dummy frames is done with the structures in the "closed" detector position. … Note: if a check of the detector positions is required, the secondary vacuum must be exposed to ambient air. However, fiducials on the center frame should give a faithful information on the position of the detector halves. ” Extract from e-mail from Massimiliano Ferro-Luzzi – March 03 Summary of discussions on survey/alignment of VELO: Present: Christian Lasseur, Jean-Christophe Gayde, Martin Doets, Massimiliano Ferro-Luzzi Date/Place: March 5, 2003, CERN Confirmed on Feb 05 Which ones? What was done ? What to be done ? Which points to meas.?  Fiducialisation at ground floor FIDUCIALISATION

4. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 4 SURVEY AT GROUND FLOOR In case of theodolite measurement Local network installation and measurement needed (Tripods …) preferably before VELO instal° => Protection of tripods against hits Additional preparation time needed 1 day Measurement of Centre Frame + Dummy Frame : 1 day in field Additional preparation time needed if theodolite measurement +1 day FIDUCIALISATION SURVEY METHOD Photogrammetry => Good candidate => Precision XYZ in object space (1 sigma) ~0.1 mm WHAT TO MEASURE ? Only Centre and Dummy Frames fiducial marks ? See questions p3 TIME NEEDED Centre Frame Fiducial Marks

5. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 5 SURVEY AT GROUND FLOOR SPACE NEEDED: 2.5 m VELO Centre Frame Dummy Frame Space needed Standard CERN Hall temperature and cleanliness are OK for Survey FIDUCIALISATION MEASUREMENT CONDITIONS

6. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 6 SURVEY AT GROUND FLOOR Questions: What is exactly to be measured (recall)? Some well defined, some less (see p.3) With which precision? On which support the VELO will be installed ? Is it necessary to adjust the support before the final measurement ? => (level? … w.r.to what?) => If so who will perform this work ? Date of this measurement ? Where: SX8 (as written in the agenda) or H156 (perhaps more space available) FIDUCIALISATION

7. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 7 SURVEY IN THE CAVERN DEMAND: Extract from e-mail from Martin Doets / Massimiliano Ferro-Luzzi – Feb 05 Survey VELO at IP8 1e; step in placing the velo is to mount the two flat rails (XZ tables) on the floor. What we need is a line on the floor along the beam center line and the position of the IP point on the floor. I also like to have a line perpendicular to the centerline. This line is the projection of the vertical plane going through the IP point, or a plane perpendicular to the beam line going through the IP point. With this cross lines on the floor we can mount the rails, and place the velo in position within a few millimeters. 2e; the alignment of the velo with the markers on the center frame. There are 5 points of alignment on each side of the center frame, and the surfaces are machined, one of the 5 in the plane of the IP. 3e; the check of the positions of the detectors with the dummy detector frames. SU will give these lines Which length? Fiducial marks Existing … Vertical projection Point and line given by SU Vertical proj IP 3.6 mrad Cavern side Floor Horiz

8. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 8 1) Tracing : in field time needed 0.5 day SURVEY IN THE CAVERN 2) Alignment of the centre frame : SU measures and provides the measured coordinates VELO Team provide the nominal coordinates and decides and do the adjustment Time needed depends on the adjustment easiness and on how and at which level of precision you plan to ajust --> Minimum 1day 3) Check with Dummy frame : in field time needed 0.5 day Dates for this survey operations ? (See p.6)

9. VELO Integr - Jan06Jean-Christophe GAYDE TS/SU EDMS n° 695362 9 Survey Infrastructure Survey Network reference already existing Position discussed with Infra people (Daniel Lacarrère) and VELO (Massimiliano) XYZ of these points known w.r.to to the Machine Geometry (Precision of XYZ at 1 sigma level 0.3mm) SURVEY IN THE CAVERN SU brackets SU ref. plates