PHENIX FVTX Status of Mechanical and Thermal Design Work Eric Ponslet, Shahriar Setoodeh, Roger Smith HYTEC Inc. FVTX Collaboration Meeting Albuquerque, NM March 12, 2007

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 2 Latest Baseline Design Still Evolving… Modular Design –Detector module (“wedge”)  Half disk  Half Cage (“clamshell”)  FVTX Wedge is Built on a Graphite Fiber/Cyanate Ester Thermal Backplane –Serves as structural support and heat transfer path to edge cooling –0.76mm thick K13CU/CyE Very high stiffness and thermal conductivity fiber Symmetric, balanced layup (won’t warp from temperature changes) Wedges are Fastened to Support Panel –Two alignment pins (ceramic?) and 3 screws (nylon) per wedge –Thick RT-cured silicone bridge provides thermal interface to cooled support panel –Allows replacement of single defective wedge BUT: requires cutting the Silicone thermal bridge Half-Disk Support Panel and Support Cage –Sandwich construction: Graphite fiber (M55J) faces and aluminum honeycomb Liquid Cooling –Tube embedded in panel in place of core, near OD of half disk –Single phase coolant at high flow rate (turbulent)

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 3 Wedge Design Backplane (0.76mm graphite fiber composite) Screw (nylon) Pin hole (for alignment) Pin hole (for alignment) HDI Connectors for extension cables Detector ROC’s (26) Screw (nylon) All bonded with rigid epoxies HDI Detector ROC’s Backplane Rigid, thermally conductive epoxy Rigid epoxy

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 4 Half-Disk Assembly Silicone bond (for heat transfer) HDI Detector ROC Screw Pin Support Tab Support Panel Support Tab

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 5 Cooling and Tab Detail Screw hole (mounting to cage) Pin hole (mounting to cage) Hose barb for coolant Screw (holds wedge on disk) Silicon detectors, HDIs, and back-planes made transparent for clarity Pin (aligns wedge on disk) ROC Built-in cooling tube Silicone heat transfer bridge (RT-cured, 2-part silicone) Silicon detector

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 6 Half-Disk Assembly: Details Thermally conductive Silicone Plastic inserts for screws and pins Single piece plastic insert for screws and pins Standoff plate Foam core Honeycomb core

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 7 Support Panel Construction Locating pin Insert for pin (TBD plastic) Insert for screw (TBD plastic) GFRP Face sheet (0.25mm) Honeycomb core (4.76mm, 32 kg/m 3 ) Foam core (TBD mat’l) Core insert for pins and screws (TBD plastic) Cooling tube Hose barb GFRP Face sheet (0.25mm) Standoff plate (TBD Plastic) Mounting tab

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 8 Half Cage Assembly Cooling hose (silicone) Station 1Station 2Station 3Station 4 Z Y

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 9 FVTX Assembly VTX Pixel barrel (#4) VTX Pixel barrel (#3) VTX Pixel barrel (#2) VTX Pixel barrel (#1) Too close! (move FVTX station 1 back?) FVTX Station 1FVTX Station 2 FVTX Station 3 FVTX Station 4 57mm54.5mm

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 10 Modularity & Testability Three Levels of Subassemblies –Can all be tested independently –Test stands will be designed –Single Wedge stand will need to incorporate cooling feature Detector Module (aka Wedge) Half Disk Module Half Cage Module

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 11 Summary of Key Requirements Environment –Operate in dry Nitrogen at atmospheric pressure and RT –Radiation dose: <200 kRad over 10 years (very low) –10 year design life Functional –Detector modules must be individually removable during initial integration –FVTX must be assembled around beam line (“clamshell design”) Heat Dissipation –100μW/channel, 128 channels/ROC –26 ROC’s/detector (stations 2, 3, 4) –10(?) ROC’s/detector (station 1) Temperature Limits (ROC and detector) –Not specified Radiation Length Limit of Station –Not specified Dimensional Accuracy/Stability –See next slide

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 12 Dimensional Accuracy Requirements Initial Alignment or Surveying Tolerance –Detector relative to station Initial assembly/surveying of half-disks X,Y< ±10μm Z< ±200μm (75μm goal) –Station location Initial assembly/surveying of half cages and complete system X,Y,Z< ±200μm Static Deformations –Non-rigid-body deformations such as temperature-induced bowing of detectors X,Y< ±10μm Z< ±14μm Stability –Unsteady Deformations and displacements (vibrations,…) X,Y< ±10μm Z< ±14μm

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 13 Radiation Length Status (1/2) Total RL of Station 2, 3, or 4 –Area averaged to active area (45mm IR, 170mm OR) = 2.2% –Worst case local value = 4.3% (going through cooling tube) See notes on next slide

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 14 Radiation Length Status (2/2) Notes: Assumes 35cm RL (X0/ρ) for coolant (no data) Assumes 1.2cm RL (X0/ρ) for Nickel (no data) Honeycomb core is treated as uniform mass distribution Titanium fittings not included (outside of active area) Screws not included (type TBD; likely nylon so small impact) Alignment pins not included (material TBD; may be removable)

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 15 Cooling Assumptions Keep FVTX (and VTX) near Room Temperature –Eliminates difficulties with cold gas enclosure flow dry nitrogen at RT –Mitigates thermal stress and dimensional stability issues Power Removed –8W per half disk (stations #2, 3, 4) Cooling Tube Embedded in 3/16” Support Panel –Square cross section (3/16” by 3/16”) with super-thin (<50μm) nickel wall Coolant –3M Novec HFE-7000 –Completely harmless to (even live) micro-electronics –Environmentally friendly –Dense (1.4 × water) Flow Regime –Single phase –Strongly turbulent Re ~ 10,000 Flow velocity ~ 0.7 m/sec Flow rate ~ 20 g/sec = 14 mL/sec = 0.86 L/min (per ½ cage) –Flow-induced vibrations?

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 16 Coolant to ROC Thermal Path Use Simple Correlations to Evaluate –Pressure drops –Temperature drop from fluid to cooling tube Approximate temperatures with 10°C coolant flowing at Re~10,000 (0.76mm K13CU backplane, 50μm Nickel tube, 0.2 W/mK epoxy, 0.75 W/mK silicone) Inside of F.S: 12.2°C Outside of F.S: 12.6°C Warmest ROC: 20.3°C Tube wall: 11.3°C backplane (K13CU) HDI Panel core (Al HC) Bulk coolant: 10°C Back of wedge backplane: 15°C Nickel tube (TBC) Inner Radius Outer Radius Foam (TBC) Thermally Conductive Epoxy Thermally Conductive Silicone

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 17 Liquid Cooling Circuit FVTX Inlet: 10°C, ~5 psig ROC station 4: ~20.6°C Outlet plane 4: 10.3°C FVTX Outlet: 11.1°C, ~3 psig ROC station 3: ~20.9°C ROC station 2: ~21.2°C Outlet plane 4: 10.6°C Outlet plane 4: 10.9°C Warmest ROC, station 1: ~21.4°C Run 4 Half-disks in Series

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 18 Wedge Analysis: Assumptions Bonds: –Silicon detector to HDI: rigid, RT-cured epoxy –ROC to HDI: rigid, RT-cured, thermally conductive (1.5W/mK) epoxy –HDI to backplane: rigid, RT-cured epoxy HDI –Multi-layer Kapton HN/Cu (2 ground planes, 2 signal planes) –Total thickness 0.176mm Backplane –QI [0°/60°/-60°] 2S K13CU/CyE graphite fiber composite –Total thickness: 0.762mm Power Dissipation –26 chips per wedge (stations 2, 3, 4) –0.0128W/chip Effective Backplane Thermal Conductivities –Estimated, based on historical test data (conservative) –K x = K y = 130 W/m.K (~5 times lower than encapsulated TPG) –K z =1 W/m.K Boundary Conditions –Bolted connections at 3 points –Silicone thermal bridge near OD –15°C at back side of backplane, near cooling tube

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 19 Wedge Analysis: Temperature Distribution 3-D Temperature Contour Max Tº = 20.3ºC Warmest ROC Min Tº = 15ºC (Boundary condition at back side of backplane) Radial Temperature Variation Radius (from beam CL, meters) Temperature (°C) Warmest ROC is 5.3ºC Warmer than Back Edge of Backplane –10.3ºC warmer than coolant

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 20 Wedge Analysis: Stresses and Distortions Assuming Assembly at RT –Max distortion of silicon detector = 10.4μm –Max normal stress in silicon = 0.5 MPa (<< 10MPa, conservative allowable) –Max shear stress in bonds = 0.8 MPa (< ~13MPa allowable) Radius (from beam CL, meters) Distortion (meters) Max deflection = 10.4μm Zero deflection (boundary conditions) Z deflection VS Radius

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 21 Wedge Design: Conclusions GFRP Backplane is –Conductive enough: 5.3°C from outer edge to ROC –Rigid enough: 340 Hz natural frequency HDI is Conductive Enough without Thermal Vias –Recommend using Kapton MT (higher conductivity) Distortions are Low –<11 μm with 10°C coolant (<14μm requirement) Stresses in Bond and Detector are Comfortably Low –No need for compliant adhesives

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 22 Disk-Level Modeling: Thermal distortion Max deflection of detector ~8μm Fundamental vibration mode: 164 Hz FEM of half disk, fully populated with detector modules Used for stiffness & Deflection calculations Distortion due to cooling

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 23 Assembly of Detector Module Assembly Concept Based on –Base tool Vacuum chuck –Keep backplane flat Holds backplane –Mechanically aligned (2 pins) –Bonding tools Aligned to base with two pins Vacuum chucks –Keep things flat One to hold HDI –HDI optically aligned (or use pins) Another to hold silicon detector –Detector optically aligned –Two-step assembly 1.Bond HDI to backplane 2.Bond detector to HDI/backplane assembly Open Questions –Shim between tools to control bond thickness? –Continuous/discontinuous bonds? 1: bond HDI to Backplane 2: bond detector to HDI/Backplane

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 24 Key Remaining Technical Issues Requirements: –RL and ROC temperature requirements –Relate to science requirements and finalize Design: –Gas enclosure Concept & design –Signal processing boards Dimensions Support structure Cooling –Cooling system Refrigeration, pumping, and control system Not currently within HYTEC’s scope Design Verification –Prototypes and performance testing Flow-induced vibrations Cooling performance Dimensional stability

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 25 Future Work: Before DOE Review Finalize and Document Requirements (LANL) –RL –Temperature limits Finish Preliminary Design (HYTEC, funded) –In progress, 3 more weeks Document Preliminary Design (HYTEC, funded) –In progress, report expected by April 6

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 26 Future Work: Before Construction Phase Not Funded, but Manpower is currently available Detailed Design –Adhesive selection, inserts, station 1 System Design –gas enclosure, “big wheel” Cooling Hardware (not in HYTEC’s scope) –Internal: tubing, clamps, etc. –External/system: refrigeration, circulation, and control system Prototyping –Detector module prototypes GFRP backplanes + dummy HDI + dummy SSD (passive silicon wafer) + resistive heaters (ROC heat) Used to –Test assembly tooling –Thermal cycling (stresses in bonds and SSD) –Heat transfer testing –Validate temperature induced deflections (TV Holography?) –Station prototype One half disk (large) Supported by dummy structure (no cage) Populated with dummy detector modules Used to –Test assembly and alignment concepts –Measure flow induced vibration (accelerometers)

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 27 Funding Issues HYTEC has No Remaining FVTX Funds –Will finish preliminary design work and write report by April 6 Funding Needed Before DOE Review –Continue refining design and updating CAD and analysis –Support DOE review (if needed) Funding Needed Before Construction Phase –Complete and finalize design –Prototyping and testing Without new funding by early April, current engineering team will have to be re-assigned to other projects

HPS – FVTX Mechanical/Thermal Design Status – March 12, 2007 – Slide 28 Concluding Remarks Structural/Thermal Design is Settling –Rigid –Stable –Modular Numerous Details still TBD –Adhesives, joint details, tooling,… Various System Issues still TBD –Gas enclosure, support and cooling of big wheel,… One Technical Question –Flow induced vibrations? Need disk prototype to evaluate Need Bridge Funding through end of FY –Continuity of engineering support Inevitable design changes to come –Remaining design tasks –Prototyping and performance testing