ATLAS Pixel Detector Pixel Support Tube Interfaces LBNL
ATLAS Pixel Detector Pixel Support Tube Interfaces LBNL Internal PST Review E. Anderssen, LBNL September 2002 Internal Review E. Anderssen LBNL
Pixel Detector ATLAS Overview • • Structures and Position in ATLAS Internal Interfaces – Rail Geometry/Sliders/Roller – Pixel to PST Mounts – PP 1/PP 0 • Mount/External Interfaces – PIXEL to SCT Mount Block – Forward End Support Flexures September 2002 Internal Review E. Anderssen LBNL 2
Pixel Detector ATLAS PST Key Structures 10 45 30 Hoop Hat Stiffeners (section view) SCT Flexures and mount pads ard w or C F l rre a B rd wa A r Fo Forward End Flexures PP 1 End Plug PST Flanges September 2002 Internal Review E. Anderssen LBNL 3
Pixel Detector ATLAS Pixel Package—Internal Interfaces PP 1 rt o pp u S e p i nd a e p am e B c rvi e S PP 0 P tec e l. D tor ixe rt e ea d. B n ea ip mp po p Su Beam pipe Support Rail Sliders Pixel Mounts Pixel Frame Rollers ic rv Se PP 1 Beam pipe Support Rail Sliders September 2002 Internal Review E. Anderssen LBNL 4
Pixel Detector ATLAS Package interfaces to PST • Package has Several Physical Interfaces to PST – Rail Sliders/Rollers on Frame and Service/Beampipe Support – Pixel Mount Blocks – PP 1 End Plate • Installation Configuration – Frame Rollers engaged, Pixel Mounts not Yet Engaged – Rails Supports Entire Detector – PP 1 Fixed Portion Clears Internal Dimensions of PST • Installed Configuration – Frame Rollers Disengaged, Pixel Mounts engaged – Rails Continue to support Services and Beampipe – PP 1(s) are Supported By PST end Flanges September 2002 Internal Review E. Anderssen LBNL 5
ATLAS Pixel Detector Inner Detector Layout September 2002 Internal Review E. Anderssen LBNL 6
ATLAS Pixel Detector September 2002 Internal Review E. Anderssen LBNL 7
Pixel Detector ATLAS 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) September 2002 Internal Review E. Anderssen LBNL 8
ATLAS Pixel Detector Patch Panel One PP 1 layout determines final length of the Forward section of the PST— Layout of region is preliminary, and will require physical modeling to complete September 2002 Internal Review E. Anderssen LBNL 9
Pixel Detector ATLAS Mount Interfaces and Geometry • • Pixel detector is supported on mounts integrated into Flange of the 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 September 2002 Internal Review E. Anderssen LBNL 10
Pixel Detector ATLAS Mount Schematic SCT Interface Block Flexure Pixel Mount Pixel Detector SCT Not shown here • • Pixel Support Tube Mounts to SCT Interface Block Via a Flexure Pixel Detector Mounts to PST Barrel Via the Pixel Mount Missing Integrated Model with both PST and Pixel Detector Frame September 2002 Internal Review E. Anderssen LBNL 11
Pixel Detector ATLAS 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 September 2002 Internal Review E. Anderssen LBNL 12
ATLAS Pixel Detector 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 September 2002 Internal Review Need to Make integrated Model/Interface Drawing with relevant parts of SCT E. Anderssen LBNL 13
Pixel Detector ATLAS 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 R 253. 5 Flexure September 2002 Internal Review PST BARREL MOUNT PAD 3 mm Shim (0 -6 mm As REQ) R 240 E. Anderssen LBNL 14
Pixel Detector ATLAS 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 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 September 2002 Internal Review E. Anderssen LBNL 15
Pixel Detector ATLAS Manufacturing Accuracy by Bonding Mistress tool or SCT AS Built Bond Between Mount Block and PST Mount Pad can be made last • • Whether SCT or Mistress tool is used depends on Schedule Bond Gap can currently account for +/- 200 m, but can easily accommodate up to 1 mm if required (need to change some nominal dimensions) September 2002 Internal Review E. Anderssen LBNL 16
ATLAS Pixel Detector Interface Geometry PST Mount Flexure SCT Barrel 3 And Interlink 253. 5 780 803 September 2002 Internal Review E. Anderssen LBNL 17
Pixel Detector ATLAS 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 (2 mm end deflections of PST) September 2002 Internal Review E. Anderssen LBNL 18
Pixel Detector ATLAS How Much Float is needed 4. 25 m @ +1 ppm/C fixed 2. 65 m @ +1 ppm/C 1. 6 m 120 m • Fixed Point to End of SCT yields an internal stress – • Fixed point to end of Cryostat yields an External load on the ID Barrel via the SCT – – -20 C • -20 C Due to CTE mismatch on the order of 1 -2 ppm/C There is potentially a large CTE mismatch between Cryostat and the Pixel Support Tube Case where Cryostat raised 10 C above no-power condition, and where Support tube CTE is unusually high (>1 ppm/C) Flexures need to assure minimal loads at these extensions yet remain stiff in the orthogonal directions +30 C 2. 65 m @ +23 ppm/C 700 m 4. 25 m @ +23 ppm/C 1. 2 mm September 2002 Internal Review E. Anderssen LBNL 19
Pixel Detector ATLAS Barrel Flexure Analysis 115 m 2. 3 m/N 50 N 147 N 0. 5 m/N 0. 17 m/N 150 N 75 m 25 m September 2002 Internal Review E. Anderssen LBNL 20
Pixel Detector ATLAS Needed Load Set on Flexure Direction Fy My Fx Mx x Limit Load Fx 121 N 450 N (~250 m) Fy 211 N 2. 3 k. N Fz 68 N 400 m (150 N)* Mx 322 N. m 750 Nm My 189 N. M 24. 6 Nm Mz 53 N. m 19. 6 Nm Fz Mz fle Load Required *Load at 400 m deflection—stop prevents further travel preventing plastic deformation of flexure. Load then transfers to bolted joint which has a limit load Equal to Fy. September 2002 Internal Review No limit in Fy foreseen due to high factor of Safety Limits in X, Z make Fo. S similar to Fy (bolted interface) E. Anderssen LBNL 21
Pixel Detector ATLAS Design of flexure against Failure Shim Fy Mz Fx Mx r ne e t as PST Mount PAD Fz Flexure My F 6 M • Flexure Yields in Z- Travel at ~400 m deflection – • Fy Ultimate for Flexure depends on Tensile stress area of Webs on Flexures – – • FX Limit to <150 m Fy=5. 2 k. Lbf • • Stops included to limit travel to 400 m or less Area of webs ~20 mm 2 area of Bolt M 6 ~20 mm 2 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 September 2002 Internal Review E. Anderssen LBNL 22
ATLAS Pixel Detector 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 September 2002 Internal Review E. Anderssen LBNL 23
Pixel Detector ATLAS 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 September 2002 Internal Review E. Anderssen LBNL 24
Pixel Detector ATLAS 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 6 Al 4 V Ti alloy with Nitrided Surface September 2002 Internal Review E. Anderssen LBNL 25
ATLAS Pixel Detector Interface to Pixel Frame Endplate • • Three mounts fixed, One adjustable vertically Two dowel pins, Three mounting screws Holes machined in Ears of Endplate registered to End frame by tight shoulder screws in same ear September 2002 Internal Review E. Anderssen LBNL 26
ATLAS Pixel Detector Pixel Mount Block and preload spring September 2002 Internal Review E. Anderssen LBNL 27
ATLAS Pixel Detector Preload Flexure • Flexure Designed for 105 N Preload – Nominally equals detector mass plus some margin • Deflection at preload nominally 1 mm – Large compliance allows for moderate machining and misalignment tolerances • Factor of Safety against yield at Max flex design travel 1. 7 September 2002 Internal Review E. Anderssen LBNL 28
Pixel Detector ATLAS Mount Deflection Budget • • • Gravity Deflection Budget of 40 m is assumed 80 Hz assumed for vibrational stability Flexure/Mount Pad-Flange/Pixel mount all contribute Assumed 20 m for Pixel mount, 20 m for rest 40 m Budget SCT Interface surface Flexure PST BARREL MOUNT PAD R 240 pixel September 2002 Internal Review E. Anderssen LBNL 29
ATLAS Pixel Detector Deflection of Mounts • • • Tip deflection of Long Shaft is 20 m. Angle change of shaft from pillow block adds 8 m. Nominal budget for Pixel mount was 20 m. – Long shaft is coupled with short PST interface block – Short shaft has less shaft deflection but more PST Pad windup • • Total Budget of 40 m between SCT and Pixels is shared between these mounts and the PST mount pad Total budget is close to met— see Neal’s talk September 2002 Internal Review E. Anderssen LBNL 30
- Slides: 30