1. PHENIX BNL ReviewFebruary 19 th, 2007 1 MECHANICAL DESIGN AND STUDIES FOR THE FVTX DETECTOR, ALONG WITH ITS INTEGRATION AS A PART OF THE VTX WALTER SONDHEIM, LANL MECHANICAL SYSTEMS ENGINEER FOR THE VTX & FVTX ERIC PONSLET - HYTEC

2. PHENIX BNL ReviewFebruary 19 th, 2007 Outline: –Mechanical Specifications and Requirements –Baseline Design –Initial Material Selection –HYTEC FEA Analysis –Wedge/Half-disk Assembly Scenario –Mechanical Integration with the VTX System 2

3. PHENIX BNL ReviewFebruary 19 th, 2007 3 Future home for the VTX and FVTX detectors: Muon arm acceptance: 12 – 35 degrees As they say in Real Estate, “location, location, location”.

4. PHENIX BNL ReviewFebruary 19 th, 2007 4 Basic components of the FVTX 15 degree wedge detector: Silicon Sensor (1) PHX readout chips (26) HDI Thermal back-plane, behind HDI 35.mm Readout connectors (2) Beam Axis

5. PHENIX BNL ReviewFebruary 19 th, 2007 5 Each large detector panel would consists of 30 - 15 degree wedges, mounted to a honeycomb core panel front-to-back, offset by 7.5 degrees in phi.

6. PHENIX BNL ReviewFebruary 19 th,2007 Mechanical Specifications and other Requirements: –The FVTX is expected to receive as much as 20 kRads exposure per year. –Nominal detector design resolution is ~20. microns or better in r and much larger in phi. –Require that the placement of the silicon sensors on a plane be placed and surveyed to an accuracy of 10. microns in x and y. –Static distortions of the planes should also be at or below 10. microns in x and y. –Static distortions in z, or a given sensor being out of plane, should be kept to 10.microns/tan(35) = 14. microns or less. 35 degrees is the maximum acceptance track angle. –Stability due to vibration must be kept less than 10. microns. –Station to station alignment in the FVTX has a goal of 75. microns, could be as high as 200. microns. Verification with straight-through tracks. –Survey installation < 200. microns. 6

7. PHENIX BNL ReviewFebruary 19 th, 2007 Baseline Design & Material Choices: –The FVTX detector will consists of 4 planes, each plane is hermetic phi. –Each detector panel consists of: One structural panel consisting of 1/4” thick (6.35mm), 2 lb/ft 3 aluminum honeycomb; 3/8” (9.5mm) cell size,.0007” (0.018mm) thick film, 5056 aluminum. Bonded using heat activated epoxy tape. Outer skins 10 mil (.25mm) thick, quasi isotropic GFRP (glass fiber reinforced polymer); –4 plies [0/45/90/-45], pre-preg unidirectional tape –M55J graphite fiber, 954-3 cyanate ester matrix, 60% FVF –Each panel 7.1 mm thick, RL 0.376% Thermal back-plane –0.25mm TPG core –0.13mm GFRP face sheets, 2 layers M55J/954-3, [0/90] HDI –176 micron thick –4 copper planes (ground, power, 2ea. Signal), 5 Kapton films, 8 glue layers Mini-strip Silicon Sensor –300 micron thick Bonds –Rigid bonds – unloaded, exception sensor to HDI thermally conductive epoxy 7

8. PHENIX Radiation Length of Baseline Design Panel total %RL –Worst case = 2.16%RL Using average of ROC+bond and SSD+bond –Area averaged = 1.84%RL Detector and HDI account for >40% of total (area averaged) Stackup of RL contributions for ½ FVTX panel (from mid-plane to detectors) One or the other, not both 8

9. PHENIX BNL ReviewFebruary 10 th, 2007 9 Baseline design for the VTX and FVTX detectors; FVTX-ROC FVTX - 4 detector planes each end Each big wheel will have 5 planes of read-out electronics, with one cooling plate for each plane

10. PHENIX BNL Review February 19 th, 2007 10 FVTX support cage: 4 stations: Support cage is a similar structure to the detector support panels – aluminum honeycomb with GFRP skins. Each half cage meshes to the mating half cage to help relieve “drum-head” effects. Each station has 15 degree sensor panels mounted on both sides – offset in phi by 7.5 degrees. FVTX mounting tabs

11. PHENIX BNL ReviewFebruary 19 th, 2007 11 sensor HDI thermal plane Cooling tube Detail view of FVTX support cage with panels: PHX chips Support cage – al. honeycomb with graphite fiber reinforced polymer (GFRP) face sheets

12. PHENIX BNL ReviewFebruary 19 th, 2007 12 HYTEC has integrated the proposed HDI to the “wedge”, that will work for all wedges. Note that the current model allows for a mech mounting for each wedge using pins and screws

13. PHENIX HYTEC - THERMAL FEA: Model represents old (worst case) baseline –35.mm IR –28 - ROC’s per SSD –About 8% more heat, and 8% longer radial heat transfer path Readout chip heat generation: –Waste heat per channel: 100  W –Channels per chip: 128 –One chip volume : 0.009×0.0015×0.0003=4.05×10 -9 m 3 –Heat generation per chip: 0.0128/4.05×10 -9 =3.16049×10 6 W/m 3 Backplane layup: –TPG core, 0.246mm thick –Symmetric [0°/90°] Gr/CyE face sheets (each layer 0.0635mm thick) –Total thickness: 0.5mm Effective backplane thermal conductivities (estimated): –K x =755.83 W/m.K –K y =755.83 W/m.K –K z =1.88 W/m.K Edge cooling at 0°C (arbitrary temperature at this point) –Backplane nodes on the outer edge are kept at 0°C –Additional temp. drop from backplane OD to fluid bulk temperature not yet included HT coefficient + TTT drops in tube wall, face sheets, bonds, etc. 13

14. PHENIX 3-D FE Model Mesh: –158,225 nodes and 270,220 elements –3-D solid elements for: backplane, glues, Kapton bus, readout chips, and strip detector Loads: –Volumetric heat generation in the readout chips –Edge cooling at 0°C 14

15. PHENIX 3-D Temperature Contour With conductive epoxy (1.5W/mK) between ROC & HDI Temperature in ºC –Assuming outer edge of TPG held at 0ºC Warmest ROC at 2.55ºC –2.5ºC <<< 50ºC –Backplane much more conductive than required 15

16. PHENIX Concluding Remarks on Thermal FEA Baseline design is simple and modular – still evolving –Duplicate functions: backplane + panel face sheets –Lots of bonds –Expensive & problematic materials (TPG) may not be needed –Good enough? Easily meets temperature requirements with edge cooling alone? (TBC) –ROC temperature < 2.6ºC –Not accounting for convection into N 2, i.e. conservative –Using TPG (~750 W/mK) may be a waste Try CC (~240 W/mK, or 3× lower) or even GFRP (~75 W/mK, 10× lower)? –No need for thermal vias through HDI Future work –Finalize specification document? –Extend model to mid-plane (represent panel) More detailed representation of cooling channel –Explore other back-plane material options –Evaluate stresses and select adhesives –Evaluate effect of convective HT (negligible?) –Cooling & flow calculations –Iterate! 16 Comments by Eric Ponslet from HYTEC

17. PHENIX HYTEC - MECHANICAL FEA: System level FEA Summary PHENIX VTX & FVTX 17

18. PHENIX FVTX Disks Honeycomb core sandwich panel are used for the disks -Symmetric quasi-isotropic [-45/90/45/0] M55J/954-3 face-sheets (t i =0.0635mm) -Aluminum honeycomb core (32.0Kg/m 3, t=6.35mm) -Total thickness: 6.858mm -Attached electronics are modeled as non-structural mass (~4.255 Kg/m 2 ) -Approximate mass of half disk: 0.234Kg (everything included) 18

19. PHENIX FVTX Cage Honeycomb Al Core with Gr/E face sheets is used for the FVTX cage Cutout design is a baseline design Disks are attached to the cage at three tabs in the current design Each half of the cage is connected to the space frame at two tabs 19

20. PHENIX FVTX Stand Alone Modal Analysis  Assumed to be fixed at the support tabs –First mode: 83.9 Hz (over predicted because of the fixed support assumption) –Even higher than the “ideal” frequency of 75Hz! –Potentially a less stiff structure could be used –Adding additional supports at the back of the cage would improve the frequency –Connecting half disks for each layer using pins and/or clips 20

21. PHENIX VTX & FVTX Assembly  First Mode: 38Hz (derived by the barrel mounts)  Can be improved by: –Connecting layer 4 barrel mounts to the space frame at 3 points rather than 2. –Increasing the thickness of the HC Al Core for the barrel mounts –Increasing the width of the barrel mounts at the base. 21

22. PHENIX System Level FEM Model System level model as of 10/13/2006 (cf. HTN-111006-0002) First Mode: 24.5Hz (Drum Head mode) 22

23. PHENIX Barrel Mount Bracings Bracings (baseline HC core sandwich panels) are added to improve the stiffness First mode increases by 55% to 38Hz Barrel Mount Bracings 23

24. PHENIX VTX Deformation Summary Staves deformation summary with barrel mount bracings installed -Max deflection is reduced by 4% Staves deformation summary with barrel mount bracings and FVTX installed 24

25. PHENIX PHENIX Assembly on Support Stand System level model with Support Stands/Rails –118,814 Nodes –147,536 Elements –712,884 degrees of freedom –First mode: 24Hz –First mode is driven by the support rails 25

26. PHENIX VTX (No Bracings) First Mode: 24Hz 26

27. PHENIX VTX with Bracings First Mode: 38Hz 27

28. PHENIX VTX+Bracing+FVTX First Mode: 38Hz 28

29. PHENIX PHENIX Assembly on Support Stands First Mode: 24Hz 29

30. PHENIX BNL ReviewFebruary 19 th, 2007 Assembly steps: –15 degree wedge – Mount HDI to the Graphite thermal plane; –Using vacuum fixtures –The HDI Kapton must be mounted as flat as possible, surfaces must be kept clean prior to bonding – suggest plasma cleaning. Install surface mount components on to the HDI; –Be certain that all solder “grunge” has been removed prior to the attachment of the silicon sensor. Silcon sensor is attached to the HDI; –Using vacuum fixtures –A suggested bonding agent is 3M 9882 thermally conductive transfer tape (CMS), 50. microns thick. –http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs6 66yazCOrrrrQ- Make wire-bond connections and encapsulate attachment points Characterize completed 15 degree wedge sensor assembly using a CMM (Coordinate Measurement Machine). Mount 15 degree wedges to support panel Again characterize assemby using CMM 30

31. PHENIX BNL ReviewFebruary 19 th, 2007 31 SIDET lab optical CMM machine, optical resolution in x-y; 3.1 microns uncertainty

32. PHENIX BNL ReviewFebruary 19 th, 2007 32 SIDET example of touch probe stations, resolution 3.5 micron uncertainty

33. PHENIX FVTX integration with VTX 33 FVTX mounts to the VTX space frame off of tabs at the front of support cage. We plan to improve the stabilization of this support cage by adding a “diving board” to the VTX space frame that will pick up an additional support point on the FVTX cage in Z.

34. PHENIX BNL ReviewFebruary 19 th,2007 Summary: –A baseline design has been developed that has been studied and modeled for mechanical and thermal stability, which meet our design requirements. –A first pass at a process for the assembly of the detectors panels and their integration into the VTX detector system has been developed. 34