W.O. Miller i T i VG 1 Two Pixel Configurations Under Study First: A Monolithic Integrated Structure First: A Monolithic Integrated Structure –Axial array of six per half structure –21.4mm wide detectors, array of 12 –6 cooling passages, double pass –800mm long structure Second: Staves with Supporting Shell Second: Staves with Supporting Shell –Circumferential array of 14 staves –16.2mm wide detector, 48 modules per stave –Overall length 778mm

W.O. Miller i T i VG 2 Integrated Monolithic Structure

W.O. Miller i T i VG 3 Preliminary Evaluation of Integrated Structure Salient points Salient points –Constraint: stay clear zone around beam pipe 70mm diameter 70mm diameter –Support split into two halves Requires equal modules around perimeter; for grouping two cooling tubes, inlet and exit same end Requires equal modules around perimeter; for grouping two cooling tubes, inlet and exit same end –Heat load assumption for 800mm length=120W Two pass for each cooling tube: 5mm ID to limit pressure drop to <200mbar Two pass for each cooling tube: 5mm ID to limit pressure drop to <200mbar Issues under study: cooling and structural support for minimum radiation length Issues under study: cooling and structural support for minimum radiation length 88mm 37.5mm 24.4mm

W.O. Miller i T i VG 4 Integrated Structure (Continued) Split Structure Split Structure –Sandwich structure, with cooling tubes embedded between 2-layer composite facing Composite laminate produced using K13D2U fibers and Cyanate Ester resin Composite laminate produced using K13D2U fibers and Cyanate Ester resin –5mils for two layers (0/90) 5 mm ID Aluminum tubing, 12 mil wall (~5.6 mm OD) 5 mm ID Aluminum tubing, 12 mil wall (~5.6 mm OD) FEA Structural Model FEA Structural Model –Tubes and foam core treated as solid elements Mass of coolant, average density 145kg/m 3 Mass of coolant, average density 145kg/m 3 –Outer surface laminate: used laminate element, with single material –Inner surface (saw-tooth) contain laminate elements with material designations for: Composite layers (0/90) Composite layers (0/90) Silicon module assembly, 0.5mm silicon Silicon module assembly, 0.5mm silicon Cable, 0.9mm uniform along length Cable, 0.9mm uniform along length

W.O. Miller i T i VG 5 Gravity Sag Model based on 1G loading vertical Model based on 1G loading vertical –Sag measured in local coordinates –T1: translation is vertical along shell split plane –Maximum sag ~2.8microns –Model length 800mm 2.8 μm

W.O. Miller i T i VG 6 Thermal: 50C Temperature Change Y Thermal strain due to cool-down Thermal strain due to cool-down –Local coordinates, T2 is transverse to vertical plane of symmetry peak shape change is 5.5microns peak shape change is 5.5microns –Model length 800mm Unfortunately the out- plane distortion is a combination of T1 an T2

W.O. Miller i T i VG 7 Thermal: 50C Temperature Change X-Direction Thermal strain due to cool-down Thermal strain due to cool-down –X: direction 8.2 to 6.6 microns X is split plane, using symmetry boundary conditions X is split plane, using symmetry boundary conditions –Model length 800mm

W.O. Miller i T i VG 8 Pixel Thermal Solution-Integrated Structure Description Description –Isotropic carbon foam: 45W/mK Specialized low density (0.21g/cc) foam: enhanced to high conductivity Specialized low density (0.21g/cc) foam: enhanced to high conductivity –Includes 5mil laminate thickness –Detector 250microns –Chips 200 microns –Bump bonds 25microns –Interface resistance from bonding chip to foam equal to 0.8W/mK; 4mil thickness (CGL7018) –Pixel chip heating: 0.51W/cm 2 –Simulated tube wall -22ºC Results Results –Peak chip edge: ºC –Detector ranges from-15.6 to ºC -17.8ºC -15.6ºC Center detector more representative

W.O. Miller i T i VG 9 Stave Approach

W.O. Miller i T i VG 10 Staves With Support Shell Issues Issues –Confined space, need additional room for support shell –Provide stave with 5 point support Minimize sag and out-of-plane distortion from sub-cooling Minimize sag and out-of-plane distortion from sub-cooling –Minimize amount of construction material Combination of high conductivity foam as before in the integrated design Combination of high conductivity foam as before in the integrated design –And two layer laminate, uni-tape or single layer of woven cloth What happens to interfacial stresses What happens to interfacial stresses –Calculated, but best resolved through testing Approach thus far Approach thus far –Design layout to compress geometry: inner diameter set at 70mm, outer diameter ? (most likely ~88mm) –Analyze basic stave stiffness and thermal performance

W.O. Miller i T i VG 11 Initial Layout-Stave 1 Concept Concept –Retained features of integrated design, same cooling tube size –Less foam, but added cylinder –Outer diameter ~93mm –Inner diameter 70mm

W.O. Miller i T i VG 12 Stave 1: Basic FEA Configuration Effects simulated Effects simulated –Mass of coolant, average density 145kg/m 3 –Laminate, 2 layers 2.5mil, 0/90, K13D2U Radiation Length estimate=0.532% Radiation Length estimate=0.532% –Foam=0.11% –Tube=0.3% –Composite=0.11% – Coolant=0.012% 5mil laminate 5.6mm OD tube 12mil wall 0.5mm of silicon to simulate chips and detector Also 0.9 mm of Kapton cable for additional mass

W.O. Miller i T i VG 13 Second Configuration-Stave 2 Goals Goals –Reduce tube size and amount of foam material –Analytically evaluate impact on thermal and mechanical design OD=88 mm ID=~69.75mm

W.O. Miller i T i VG 14 Stave 2: With Offset Mounts Space on back-side next to mounts appears adequate to place cable, for wrap-around mounting Space on back-side next to mounts appears adequate to place cable, for wrap-around mounting Cable position (for thermal analysis) Potential cable location

W.O. Miller i T i VG 15 Stave 2: With Offset Mounts Cable Illustration Cable Illustration –Back side, thin bonding wraps around –Cable on back-side becomes thicker as the stave end is approached Cable constant thickness in this region

W.O. Miller i T i VG 16 Stave 1: Gravity Sag Upper Stave position near vertical centerline Upper Stave position near vertical centerline –Modeled ½ length, from mid plane of symmetry of a 778 mm long stave –Model provides effect of a 5 point support stave length Resulting gravity sag 0.085microns Resulting gravity sag 0.085microns Does not include support shell sag

W.O. Miller i T i VG 17 Stave 1: Thermal Distortion Cool-down effect: 50°C Delta Cool-down effect: 50°C Delta –Most of distortion is contraction along stave length –Distortion T2 is out-of-plane –T2 peak distortion is 5.6microns

W.O. Miller i T i VG 18 Stave 1: Thermal Strain Stress in Foam/Tube Interface Stress in Foam/Tube Interface –Evaluated without compliance of bonding adhesive (CGL7018 type) –Contraction of Al tube produces local stress of 300psi at interface Effect best evaluated through testing Effect best evaluated through testing –Plan is to use special Reticulated Vitreous Carbon Foam with enhanced thermal and mechanical properties Solid Von Mises Stress

W.O. Miller i T i VG 19 Stave 2: Gravity Sag Upper Stave position near vertical centerline Upper Stave position near vertical centerline –Modeled ½ length, from mid plane of symmetry of a 778 mm long stave –Model provides effect of a 5 point support stave length Resulting gravity sag 0.41microns Resulting gravity sag 0.41microns Does not include support shell sag

W.O. Miller i T i VG 20 Stave 2: Gravity Sag-Off Set Mount Effect on rotation of stave Effect on rotation of stave –Maximum rotation 1.9 μradians due to sag

W.O. Miller i T i VG 21 Stave 2: Thermal Distortion Stave with out-of-plane bending due to cool-down 50°C Stave with out-of-plane bending due to cool-down 50°C –Modeled ½ length, from mid plane of symmetry of a 778 mm long stave –Model provides effect of a 5 point support stave length Resulting bending 51.5 microns Resulting bending 51.5 microns

W.O. Miller i T i VG 22 Stave 2: Thermal Strain Stress induced by contraction Stress induced by contraction –Less than in Stave 1 geometry –145psi, more localized at ends –Be mindful that compliance of adhesive not present

W.O. Miller i T i VG 23 Stave 2: Thermal Solution Model Parameters Model Parameters –Carbon Foam, 45W/mK –Composite Facing, K13D2U-55% vol fraction 0/90, K t =0.55W/mk, 220W/mK planar (no axial thermal gradient so this parameter is not an issue) 0/90, K t =0.55W/mk, 220W/mK planar (no axial thermal gradient so this parameter is not an issue) –Chip 0.2mm –Bump bond thickness,.05mm –Detector, 0.25mm Adhesives Adhesives –Tube to foam, 4mils, 0.8W/mK –Foam to composite facing, 2mils, 0.8W/mK –Chip to composite facing, 4mil, 1.29W/mK –Cable to detector module, 2mils, 1.55 W/mK

W.O. Miller i T i VG 24 Stave 2: Thermal Solution-No Cable Coolant Tube “BC” Coolant Tube “BC” –-22ºC Chip Heat Flux, 0.6W/cm 2 Chip Heat Flux, 0.6W/cm 2 Detector Temperatures Detector Temperatures –Left edge, ºC –Middle, ºC –Right, ºC

W.O. Miller i T i VG 25 Stave 2: Thermal Solution-With Cable Cable heat load Cable heat load –Adds a heat flux of 0.1W/cm 2 to the 0.6W/cm 2 chip heat load –Gradient before was 4.99ºC, detector middle to tube inner surface –Would expect gradient of 5.82ºC now –Gradient now from detector middle to tube surface is 6.0ºC Cable surface Cable surface –Peak -14.1ºC, or a ΔT=7.9ºC –Peak affected by K assumed for the copper/Kapton cable Used 0.35W/mK, whereas Kapton alone is 0.12 Used 0.35W/mK, whereas Kapton alone is 0.12

W.O. Miller i T i VG 26 Stave 2: Thermal Solution-With Cable Thermal plot with cable removed Thermal plot with cable removed –Illustrates comparative uniformity in detector temperature

W.O. Miller i T i VG 27 Detector Temperature Summary Thermal Solutions for two designs, but unfortunately different detector layouts Thermal Solutions for two designs, but unfortunately different detector layouts –Integrated, different by chip over-hang –Stave-like, provides complete coverage Two different foam/sandwich structures, one with less material analyzed first Two different foam/sandwich structures, one with less material analyzed first With time will bring configurations into consistency With time will bring configurations into consistency However, the predicted detector surface temperature for each is: However, the predicted detector surface temperature for each is: –Low-mass stave without cable heat load, -17ºC –Low-mass stave with cable heat load, -16ºC –Integrated Foam/Tube Support without cable load, -17.5ºC Caution, as analysis proceeded slightly more conservative properties were used for the composite facing and the foam: Caution, as analysis proceeded slightly more conservative properties were used for the composite facing and the foam: –Facing 0.55W/mK versus 1.44W/mK –Foam 45W/mK versus 50W/mK

W.O. Miller i T i VG 28 Suggestions for Future Work Benefits of Continued Analysis Benefits of Continued Analysis –Improve definition of concept Preliminary results encouraging, but issues will emerge with increased knowledge base Preliminary results encouraging, but issues will emerge with increased knowledge base Add support shell deflection, support boundary conditions, end plates etc. Add support shell deflection, support boundary conditions, end plates etc. –Cooling analysis Conservatively used 0.6W/cm 2 for chip thermal load, revise as electronics design progresses, also expand on cable thermal load (location) Conservatively used 0.6W/cm 2 for chip thermal load, revise as electronics design progresses, also expand on cable thermal load (location) Tube sizing analysis needs more careful consideration Tube sizing analysis needs more careful consideration –Preliminary pressure drop with smaller tube appears OK with C 3 F 8  An area that needs more study, pressure drop prediction indicates low margin on return pressure –Consider tube shape change to reduce outer diameter (<88mm?) Prototyping Prototyping –Thermal and structural prototypes

W.O. Miller i T i VG 29 Suggestions for Future Work (Cont.) Basic Stave Concept uses Lightweight Sandwich Basic Stave Concept uses Lightweight Sandwich –Continued Material development Important to Success Carbon foam development Carbon foam development –Have produced 45W/mK foam  By very nature of HEP goals, heavier than desired Incentive: Advance through development with carbon nano-tubes additives Incentive: Advance through development with carbon nano-tubes additives –Stronger, lighter, more conductive?