M. Gilchriese Disk Geometry January 18, 2005

M. Gilchriese 2 ATLAS Coordinate System

M. Gilchriese 3 The Parts Modules on disk sectors – Ron’s talk Sectors mounted on rings Rings mounted into disk frame sections Disk frame sections joined to barrel section(barrel to disk alignment) Pixel mounts attached to plate at ends of disk frame section Pixel mounts engage Pixel Support Tube(PST) PST(barrel) mounted to SCT barrel structure SCT attached to TRT TRT mounted on rails inside cryostat

M. Gilchriese 4 Ideal Module Locations on Disk

M. Gilchriese 5 The Rings Adjustable mounts glued into frame Sectors precisely bolted to ring

M. Gilchriese 6 Ring Survey All rings were surveyed literally years ago using the SmartScope However this was done before the final mounts were in place(just pins used). This translates into a small uncertainty in the 0,0 location that we propose is done in the alignment software.

M. Gilchriese 7 Ring 3(C3)

M. Gilchriese 8 Frame is Drilled Z DRILL Z BARREL+ENDCONE X Z IP NOT TO SCALE! Z(Barrel+Endcone) is measured Other numbers are averages of measured values. We could correct sector by sector and ring-by-ring using measurements. The corrections would be max about 20 microns

M. Gilchriese 9 Ring and Mounts Glued Precision tooling is used to glue the ring-part of the mounts into the rings. Different tooling is then used to position the rings and glue part that goes into the frame. The tooling determines the ring position. We believe this was accurate to roughly 15 microns but no survey has been done(and would be hard to improve on this accuracy anyway)

M. Gilchriese 10 Disk Insertion This will utilize pretty much the same tooling that was used to glue the ring mounts into the frame. Thus the Z-locations will be identical to just bare rings. The X-Y locations might vary, since the mounts have to be backed out and then screwed in when the ring is in position. We will try this more to understand the reproducibility. This will also give us a measurement of the ring hole locations relative to the barrel endcones – a starting point on barrel-disk alignment

M. Gilchriese 11 Frames and Pixel Mounts The ring locations will be “transferred” to the pixel mounts through the EndFrame EndFrame is pinned and bolted to the barrel frame EndPlate is bolted to EndFrame and pixel mounts are aligned(pinned) to EndFrame. The four mounts are adjusted to lie within a plane.

M. Gilchriese 12 Support Tube

M. Gilchriese 13 Current Plan Review ring survey data(ring for disk 3, side C) by Jan. 24. Jon and I are doing this. Measure reproducibility of rings in end-frame and develop simple(non-CMM) means to reference to pins in EndFrame by March. Do not survey modules on disks – sectors on rings. Too risky. Practically this means taking the sector and ring measurements and creating a new XY “drawing” – actually a table - for each module. Z is more complicated but much less sensitive. Note that forces from pipes and cables will deflect sectors by amounts that cannot be measured during assembly – no access. We need to decide how to use module-on-sector Z measurements.