Pixel Support Tube Interfaces

1. Pixel Support Tube Interfaces LBNL Internal PST Review E. Anderssen, LBNL

2. Overview • Structures and Position in ATLAS • Internal Interfaces • Rail Geometry/Sliders/Roller • Pixel to PST Mounts • PP1/PP0 • Mount/External Interfaces • PIXEL to SCT Mount Block • Forward End Support Flexures E. Anderssen LBNL

3. PST Key Structures 10 45 30 Hoop Hat Stiffeners (section view) SCT Flexures and mount pads Forward C Barrel Forward A Forward End Flexures PST Flanges PP1 End Plug E. Anderssen LBNL

4. Service and Beampipe Support Pixel Package—Internal Interfaces PP1 Service and Beampipe Support PP0 Pixel Detector Beam pipe Support Rail Sliders Pixel Mounts Pixel Frame Rollers Beam pipe Support Rail Sliders PP1 E. Anderssen LBNL

5. Package interfaces to PST • Package has Several Physical Interfaces to PST • Rail Sliders/Rollers on Frame and Service/Beampipe Support • Pixel Mount Blocks • PP1 End Plate • Installation Configuration • Frame Rollers engaged, Pixel Mounts not Yet Engaged • Rails Supports Entire Detector • PP1 Fixed Portion Clears Internal Dimensions of PST • Installed Configuration • Frame Rollers Disengaged, Pixel Mounts engaged • Rails Continue to support Services and Beampipe • PP1(s) are Supported By PST end Flanges E. Anderssen LBNL

6. Inner Detector Layout E. Anderssen LBNL

7. E. Anderssen LBNL

8. Patch Panel Zero Pixel Mount Block Access Frame Rollers Service Sliders PPO region preliminary layout—cable routing and assembly sequence not completed Nominal routing for tubes shown here—allows access to rails and pixel supports (discussed later) E. Anderssen LBNL

9. Patch Panel One PP1 layout determines final length of the Forward section of the PST—Layout of region is preliminary, and will require physical modeling to complete E. Anderssen LBNL

10. Mount Interfaces and Geometry • Pixel detector is supported on mounts integrated into Flange of the Barrel PST • Barrel PST is mounted to the Barrel SCT via Flexures and fixed Support • Mount Pad integrated with Flange of Barrel PST directly couples SCT and Pixels decoupling as much as possible the shell of the PST • Forward PST sections are mounted to the Barrel PST via a flange, and supported at their ends from the PST Support structure (formerly Beampipe support) • Rails discussed later, however for completeness: • Pixel Detector rides in with package on rails and transitions to mounts in the Barrel section of the PST • Remainder of Package (Service/Beampipe support Structure) remains on rails E. Anderssen LBNL

11. Pixel Support Tube Mounts to SCT Interface Block Via a Flexure Pixel Detector Mounts to PST Barrel Via the Pixel Mount Mount Schematic SCT Interface Block Flexure Pixel Mount Pixel Detector SCT Not shown here Missing Integrated Model with both PST and Pixel Detector Frame E. Anderssen LBNL

12. Interface to SCT Interlink(Barrel PST support) • Pixel Support Tube is supported by Three Flexures and One “Fixed Support” • All Flexures and the Fixed Support have identical bolted and pinned interfaces with PST Barrel and SCT Interface Block • Interface Blocks which penetrate the SCT Thermal Enclosure are mounted to the SCT Interlink • All Interface Blocks are identical • Brief modification of the end of the interlink to accommodate • Penetration through SCT Barrel Thermal enclosure standardized E. Anderssen LBNL

13. Proposal for SCT - Pixel Interface - 4 Blocks fastened to the SCT horizontal interlinks - Adjustement, if needed, by shimming or machining PST blocks Dimension Is OK Slide of E. Perrin Need to Make integrated Model/Interface Drawing with relevant parts of SCT E. Anderssen LBNL

14. SCT Inner thermal enclosure - I propose to fix the TE inner cylinder directly to Barrel 3 - To save space. - To try to simplify penetrations and sealing. Z 780 R253.5 Flexure 3mm Shim (0-6mm As REQ) PST BARREL MOUNT PAD R240 E. Anderssen LBNL

15. Manufacturing and Assembly implications • Flexures Mount Directly to SCT Interface Block (prior to PST Insertion) • Mounting Pixel Support Tube requires access to inside of Barrel PST • Pins and bolts into Flexure are accessed through cutout • “Adjustment” is by shimming (horizontal) and flexure replacement (vertical) • Adjustment only required in emergency in pit—nominally PST is centered in SCT • Above implies that set of pre-machined flexures will be required • Pinned interfaces require accurate mating and alignment of interfaces • Proposed solution is to Bond PST mount Pads in place • Depending on Schedule either Transfer Tooling or Bond in place E. Anderssen LBNL

16. Manufacturing Accuracy by Bonding • Whether SCT or Mistress tool is used depends on Schedule • Bond Gap can currently account for +/- 200m, but can easily accommodate up to 1mm if required (need to change some nominal dimensions) Mistress tool or SCT AS Built Bond Between Mount Block and PST Mount Pad can be made last E. Anderssen LBNL

17. Interface Geometry SCT Barrel 3 And Interlink PST Mount Flexure 253.5 780 803 E. Anderssen LBNL

18. Mount Block Analysis • Flexures chosen for tight packaging Accurate manufacture and predictability of analysis • Large Factors of Safety against yield at maximum foreseen loads • Have assumed that loads from Integrated SCT/PST model represent worst case loads (2mm end deflections of PST) E. Anderssen LBNL

19. Fixed Point to End of SCT yields an internal stress Due to CTE mismatch on the order of 1-2ppm/C Fixed point to end of Cryostat yields an External load on the ID Barrel via the SCT There is potentially a large CTE mismatch between Cryostat and the Pixel Support Tube Case where Cryostat raised 10C above no-power condition, and where Support tube CTE is unusually high (>1ppm/C) Flexures need to assure minimal loads at these extensions yet remain stiff in the orthogonal directions How Much Float is needed 2.65m @ +1ppm/C 4.25m @ +1ppm/C 1.6m 120m fixed -20C -20C +30C 2.65m @ +23ppm/C  700m 4.25m @ +23ppm/C 1.2mm E. Anderssen LBNL

20. Barrel Flexure Analysis 115m 2.3m/N 50N 147N 0.5m/N 0.17m/N 150N 25m 75m E. Anderssen LBNL

21. Fy My Fz Mz Fx Mx Needed Load Set on Flexure flex *Load at 400m deflection—stop prevents further travel preventing plastic deformation of flexure. Load then transfers to bolted joint which has a limit load Equal to Fy. No limit in Fy foreseen due to high factor of Safety Limits in X,Z make FoS similar to Fy (bolted interface) E. Anderssen LBNL

22. Flexure Yields in Z- Travel at ~400m deflection Stops included to limit travel to 400m or less Fy Ultimate for Flexure depends on Tensile stress area of Webs on Flexures Area of webs ~20mm2 area of Bolt M6 ~20mm2 Fx will have limits built into interface pads as shown in figure above on right Built Prototype Flexure without Stops to verify plastic limits Will test Stiffness of Flexure with TVH system Design of flexure against Failure Shim Flexure PST Mount PAD Fy My Fz Mz Fx Mx M6 Fastener FX Fy=5.2kLbf Limit to <150m E. Anderssen LBNL

23. Forward Flexure 80 Plastic Limit stop will be incorporated in design, and integrated with Flex lock mechanism necessary for lock-out during Installation of Pixel Detector E. Anderssen LBNL

24. Pixel Support Condition on PST • This is an attempt at a pseudo-kinematic mount condition • Three points are fixed, with one adjustable in height—nominally this is one of the ‘flat’ mounts • Mounts will be adjusted in co-planarity to match mount surfaces—reducing twist of frame E. Anderssen LBNL

25. Pixel Frame Mounts • Prototype of Pixel mounts developed • Axle and Bearing design refined • Angular contact bearings • Ceramic race • Ceramic Balls • Titanium Shaft • Contact analysis shows one ball can take full detector load (no brinnelling) • Statistical tolerance analysis shows 5 or more balls in contact • Shaft is Full Hard 6Al4V Ti alloy with Nitrided Surface E. Anderssen LBNL

26. Interface to Pixel Frame Endplate • Three mounts fixed, One adjustable vertically • Two dowel pins, Three mounting screws • Holes machined in Ears of Endplate • Endplate registered to End frame by tight shoulder screws in same ear E. Anderssen LBNL

27. Pixel Mount Block and preload spring E. Anderssen LBNL

28. Preload Flexure • Flexure Designed for 105N Preload • Nominally equals detector mass plus some margin • Deflection at preload nominally 1mm • Large compliance allows for moderate machining and misalignment tolerances • Factor of Safety against yield at Max flex design travel 1.7 E. Anderssen LBNL

29. Mount Deflection Budget • Gravity Deflection Budget of 40m is assumed80Hz assumed for vibrational stability • Flexure/Mount Pad-Flange/Pixel mount all contribute • Assumed 20m for Pixel mount, 20m for rest 40m Budget SCT Interface surface Flexure PST BARREL MOUNT PAD R240 pixel E. Anderssen LBNL

30. Deflection of Mounts • Tip deflection of Long Shaft is 20m. • Angle change of shaft from pillow block adds 8m. • Nominal budget for Pixel mount was 20m. • Long shaft is coupled with short PST interface block • Short shaft has less shaft deflection but more PST Pad windup • Total Budget of 40m between SCT and Pixels is shared between these mounts and the PST mount pad • Total budget is close to met—see Neal’s talk E. Anderssen LBNL