STAR PIXEL Detector - Mechanical

1. STAR PIXEL Detector - Mechanical April 2008

2. STAR PIXEL Mechanical • Mechanical requirements and constraints • Participants • PIXEL mechanical system • Work on mechanical stability with rapid installation • Work on air cooling • Work on detector integration into STAR

3. Tracking from outside in to locate the vertex • Outer layers provide hit to track association and a measure of momentum • PIXELS, inner two layers provide high resolution vertex location • Required Resolution • TPC  SSD ~ 1 mm • SSD  IST ~ 400 m • IST  PXL 2 ~ 400 m • PXL 2  PXL 1 ~125 m • PXL 2 + PXL 1  Vertex ~ 40 m TPC SSD IST PXL 2 PXL 1 smaller is always better, no limiting requirement

4. PXL pointing resolution and associated requirements • Multiple coulomb scattering limited – no reason to have better hit resolution than 9 m • hit resolution sets limit of pixel to pixel mechanical stability – better than 9 m • PXL unit stability set by pointing resolution of IST – better than 125 m (see previous slide)  1=2=9 m =(13  19GeV/pc) m

5. Mechanical effort • Eric Anderssen (Project Engineer), LBNL engineer working on ATLAS pixels is phasing into our pixel program – full time end April 2008 (carbon composite expert) • Contracted ARES Incorporated for analysis on cooling, precision mount design and refinement of ladder stability. • Phone meetings weekly • First results – • May need Sub-Ambient Cooling to meet goals set at time of contract • Precision Mount • Sources of Sector Mechanical instability, temperature variation, gravity and air flow under control • Latest number for moisture adsorption encouraging but needs further work • First stage report received • Results of Hygro-Thermo-Structural Stability (and vibration) • Kinematic mount design and load transfer • Some parallel analysis effort at LBNL

6. Pixel support structure – current development End view 8 cm radius 2.5 cm radius Inner layer Outer layer ALICE style carbon support beams (green)

7. HFT Pixel Structure Installed (Concept) Articulation Pantograph ‘D-Tubes’ covered by Pixel Services ‘ISC’ Beam Pipe Supports Support Rails and Table Also supports External Service ‘Card Cages’ Articulation Guides 7

8. Follower guided insertion operation Clearance for Beam Pipe Supports and Kinematic Mounts Final Motion engages Kinematic Mounts Articulation Region Clears Beam Pipe over Large Diameter Closed Open 8

9. Pixel placement concept Detector assembly slides in on rails Parallelogram hinges support the two detector halves while sliding Cam and follower controls the opening of the hinges during insertion and extraction Detector support transfers to kinematic dock when positioned at the operating location pixel support hinges kinematic dock sliding carriage Reason for no bottom Beam Pipe support… cam followers and linear cam slide rails 9

10. Components Developed with Ares Kinematic Mounts Inlet Duct ‘D’ Tube ‘Strong Back’ with Cam-Follower (part of articulation hinge) Load Transfer Mechanisms 10

11. Load Transfer from insertion table to Mounts 11

12. Engineering Installation Requires that all of delivery system, and kinematic mounts are available by then (half if only 2 sectors installed) New Beam Pipe, ISC, Articulated rails/D-tube, and Modified East Cone 12

13. Sector/ladder design—what was analyzed Heat loads defined by region on MAPS chips and End of Ladder electronics carbon composite support beam thinned MAPS chips 2 cm by 2 cm, 50 µm thick multilayer aluminum kapton flex circuit cable for signal and power thin carbon composite substrate 13

14. Internal Fins base lined for further Analysis Eric Anderssen • Flow rates of 4-8m/s used—produces flow in the 50CFM range, which seems reasonable • Fins required to improve heat transfer area, given Heat Transfer coefficients for air of this velocity • Fins also improve some of the structural deformation modes, but add material • Don’t know how to build fins yet • Have not modeled air flow, so cooling rates likely optimistic • Fin size and position likely needs further optimization • Need to build prototypes to guide this 14

15. For flow on inside only, most recent result 15

16. Displacement from imposed Thermal Distribution No Silicon 16

17. Parallel LBNL analysis effort indicates that a very low shear adhesive is necessary to control thermally induced deformations.

18. Hinge analysis—Mount Engagement Forces +0.015mm ~0mm +Y -0.14mm Analysis of initial hinged parallelogram concept; additional concepts are also being investigated to understand if an even simpler solution is available. Analysis shows that this is viable 15kgf (~150N) applied at end of magenta links (rigid elements) Stresses are low (from an alternate analysis not shown) Deflections are shown on Y axis only (note reversal) Max Deflection is 0.14mm (negative Y) Aim is to show that Hinge, under insertion load will hold kinematic mounts within appropriate acceptance window of Kinematic Mounts Analysis shows this is currently acceptable 18

19. Cut Apart Current Cones August 2009 Keep at Brookhaven Send to Berkeley Eric Anderssen Old East Cone and most of Beams to be reused to support New West Cone Old West cone refurbished into New East Cone in Berkeley Cut Carbon Elliptical Beams avoiding Al Insert 19

20. Modified East Cone and Install with New West Cylinder ~1.5m Some Tooling Required… Buck Plate aimed for Easy Swap of replacement Eric Anderssen • View as Temporary Fix—Should be ACAP (as cheap as possible) • Supports end of New West Cone/FGT • Replicates Old Beam Pipe Interfaces • Includes SSD if required • Only for summer ’09 to ‘10 • Wholly Machined/Bonded Solution • Tooling to locate Buck Plate while bonding is required…

21. Goal—Swap-in Replacement and Install pixels – summer 2010 New East Cone with Cylindrical Shell made from Old West Cone Swap in by matching Bolted Interface to New West Cone… Include SSD interface On Shell Modification Will Take Up Length… Should Be Same Length Eric Anderssen

22. Inner Support Cylinder (ISC) ISC fits inside and is supported by the cone ISC supports IST on outside ISC supports pixel and beam pipe inside ISC

23. Layout of Insertable Cone Structures in IFC SSD Room Temp IST -15C(?) Gap for ISC services Required thru ISC support off of NCS Pixels Cartooned in Anderssen • Note that SSD and FGT will likely be installed before internal system (IST/PXL) is available • If SSD not installed could pre-integrate on outside of New East Cone prior to opening… • Aim is for quick integration of these during any one opening • As much pre-integration as possible prior to opening is a priority • ISC with Beam Pipe and IST are inserted first into Cone Structure (with FGT and SSD installed) • ISC needs to be removed to install IST if it lags pixels 23

24. ISC Integrated with IST and Beam Pipe Include Service Penetration/Seal Double support provides moment constraint for insertion Insertion Rails Asymmetric Beampipe Allows for Articulation of Pixels to small Radius prior to insertion into smaller cylinder Separate Cylinders (bolted Interface) • Smaller cylinder has both IST and Beam pipe supports Integrated • Integrate IST first on Small Cylinder where appropriate (MIT or BNL) • Insert Beampipe and fix on mounts • Requires long bench to support Beam Pipe until full load transfer to ISC • Right hand side eventually cantilevered by this structure for insertion into Cone Structure • Add large cylinder, transfer Beampipe to top support • no permanent bottom support—interferes with Pixel insertion rails/tooling) • Dress IST Services on outside of large Cylinder 24

25. Assembly Sequence Aims at Parallel Integration ISC IST IST IST IST IST/ISC follows FGT by ~1yr Pixel Compatible BP ‘should’ be ready… SSD Integration PXL IS Insertion (includes BP and IST) SSD ’09-10? NCS FGT ISC FGT Integration (COMPLETED PRIOR) Beam Pipe Integration SSD Integration Done independently (as required) SSD IST Integration Intention to place PXL engineering ‘patch’ system as early as possible—preceding IST Installation PXL PXL Insertion (after Cone in STAR) Insertion into STAR 25

26. Summary • PIXEL mechanical initial analysis on cooling, support stability finished • Next step is prototyping with the return of Eric Anderssen to full time STAR effort • Initial work progressing on integration and overall detector and beam pipe support and instillation.