1. 1 1F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Update on Thin Mechanics/Cooling R&D for the Layer 0 of the SuperB Factory F. Bosi - M. Massa INFN-Pisa on behalf of the SuperB Group

2. 2 2F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Outline L0 physics and mechanical requirements Prototypes construction Module design developments –Ceramic –Carbon fiber Thermal studies Conclusions

3. 3 3F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 General Considerations Remember the main requirements for MAPS sensor L0 support : 1. Need to evacuate the sensor Power (about 20 kW/m 2, sensor temperature below 50 °C ) 2. The L0 MAPS support (w/o cables and sensors) has to remain as low as possible ( anyway below 0.53% X 0 ) (see Giuliana’s talk at the last Collaboration Meeting).

4. 4 4F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 General Considerations The second statetment is due to the following physics and technological considerations: a) Total radiation length of L0 < 0.8 % X 0 b) Sensor MAPS can be thinned down to 50  m, (for N.2 layers means 0.1% X 0 ). b) Signal-Power multicable takes in total 0.17 % X 0 (Pixel Alice experiment)

5. 5 5F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Module Design Development We decide to study a kind of cooling with an heath sink close to the sensors (even at the internal of the support structure) using mono-phase thermal exchange in minichannel technology. For this purpose we use two kind of materials: a)Ceramics (AlN) (good thermal conductivity) b)Carbon Fiber Composite Materials (high radiation lenght) For both materials we are making prototypes in order to get experimental results to validate thermal analysis simulations.

6. 6 6F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Ceramic Support Module We are still waiting delivery of ceramics slats with microchannel from our collaborating company. In the mean time we start with trivial construction of thin single channel supports prototypes by bonding single pieces (epoxy), in order to have material to start with TMF laboratory test.

7. 7 7F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Cooled channel Module Layout : Minichannel cooling in the support First prototypes in ceramics we realized : 0.58 % X 0 0.270

8. 8 8F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Different layouts to build : Module Layout Minicanale a trees Double thin minichannel with reticule Parallel minichannel Trees thin minichannel Double thin minichannel Single thin minichannel

9. 9 9F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Module Layout Development (Ceramic) Support components Lateral gluing particular Realized slats First realized slat

10. 10 10F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Module Layout Development 125 mm Ready to be thermally and mechanically characterized 12.8 mm 900  m 350  m 2 mm

11. 11 11F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Module Layout Development Lateral gluing Ceramic support with hydraulic interface Ceramic support thin single channel 12.8 mm 3 mm

12. 12 12F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 AlN slat micromachining Some example of micromachined ceramic slats, 270  m thick AlN Slat, 270  m thick with minichannel AlN Slat, 270  m thick with double thin channel AlN Slat 270  m thick. Minichannel top view (pitch 400  m ) ( pitch 400  ) 150  m 200  m We are waiting optimized ceramics with microchannel from collaborating company to start in the bonding !

13. 13 13F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Carbon Fiber Support Module Two construction methods Subtractive methods Additive methods Actually several prototypes in construction with different channels dimension (n.7 channels 1x0.35 mm 2 ) (n.3 channels 2.5x0.35 mm 2 ) Coating for fluid sealing obtained with epoxy (thick 30-40  m). This consist in compose several microtube in C.F. to obtain a larger support structure! - Actually available C.F. microtubes 0.3/0.7 mm diam. -Microtube in peek 0.3/0.4 mm diam. needed for water sealing. - Special tooling to construct to obtain an external square section as solid base for microcables bus support. Minichannel in carbon fiber in production with subtractive technique.

14. 14 14F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Carbon Fiber Support Module Subtractive methods: Carbon fiber plate milling machined 12.8 mm 2.5mm Support thickness 1100  m Subtractive method

15. 15 15F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Carbon Fiber Support Module Ready to be tested 125 mm N.7 channelsN.3 channels Slat support showing internal stucture Hydraulic interface Subtractive method

16. 16 16F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Carbon Fiber Support Module caterpillar - Coating obtained with epoxy dispensed by aerographic method ( 30-40  m thick). - Collaborating Company suggests to use 100  m thick adhesive film (epoxy) to cover the channels by thermal cicle. -Next prototypes will be built with this feature. Not coated Coated 1 mm Subtractive method

17. 17 17F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Carbon Fiber Support Module 700  m 1000  m 700  m 300  m Composite poltrusion carbon tubes in our hand for first prototypes.. -Technological development to pass to a square C.F. shape and to match peek tube. 700  m Peek tube 50  m thick (i.d.=300  m) 700  m Additive method

18. 18 18F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Carbon Fiber Support Module - Next development: to use carbon fiber with very high modulus and matrix epoxy with carbon nanotube to implement thermal conductivity. The total support is obtained gluing laterally each single square tube (epoxy). (N.18 square microtube needed to form one L0 module support ). Additive method

19. 19 19F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Thermal Study / 1 We have done a thermal study of the L0 module using a CF support structure with a circular hole in the logic additive technics. The inner diameter of the tube is 0.4 mm, the external dimensions are 0.7 mm x 0.7 mm. Inside we have a peek tube 50 mm thick. The module is assembled gluing 18 single parts (total dimension 12.8 mm). In our study we have considered only a single square microtube part, (0.7 mm x 0.7 mm with a circular hole).

20. 20 20F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Thermal Study / 2 In order to study the thermal gradient between the cooling fluid and the silicon surface we used the analogy between the Ohm’s law and the Fourier’s Law (conductive law). The scheme used is the following: Where: R h is the resistance of the fluid (convective term) R peek is the resistance of the peek inner tube R CFRP is the resistance of the CF support structure R glue is the resistance of the epoxy glue R cable is the resistance of the chip-cable R Si is the resistance of the silicon sensor

21. 21 21F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Thermal Study / 3 The results : Thermal Conductivity, K (watt/mK) Thermal Gradient (K) Resistance (K/watt) Silicon 1240.0090.005 Epoxy Glue 0.283.572.04 Cable Average between Al & Kapton 4.42.51 CFRP 200.20.114 PEEK 0.255.943.4 WATER 0.583.72.123 The total gradient is about 21.5 °C

22. 22 22F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Radiation Length / 1 We have also evaluated the average thickness in radiation length of the module used for the thermal calculations by uniformly distributing the cooling channel along the section of the microtube. The scheme used is the following: Average thickness

23. 23 23F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Radiation Length / 2 Radiation lenght (mm) % of Radiation Length Average thickness (mm) SILICON 93.70.1 EPOXY GLUE 2800.080.2 CABLE (kapton/Al) 285/900.05/0.12=0.170.11/0.11 CFRP 2500.2080.52 PEEK 2500.0310.08 WATER 3600.030.1 TOTAL  0.62 0.35 % X 0 The total thickness of the supportstructure + cooling fluid + peek + glue is: 0.35 % X 0 (Consistent with the requirements). Average Thickness 0.62%

24. 24 24F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Thermal-fluidodynamic Laboratory Scheme of the Test-bench hydraulic circuit Free from the last commitments, now we are setting-up the TMFD laboratory : all the components are in our hands (chiller, HW and SW DAQ system, temperature and pressure sensors, kapton flexible heater). The test vacuum chamber is still under design.

25. 25 25F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 TMFD Lab Test Section In order to test our modules prototypes we are designing a Vacuum Test Section in stainless steel with temperature and pressure probes, I.R.viewports, vacuum pump, etc. to measure thermal exchange parameters. In the picture a simplified model of this Vacuum Test Section. 600 mm 300 mm

26. 26 26F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 The Thermal-fluidodynamic Laboratory DAQ HW system (N.24 probe for temperatures, pressure and flux ). Chiller (dimensioned for a cooling power > 1/2 kW (~1 Layer0 equivalent). Primary and secondary cooling circuit

27. 27 27F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Future design activity - Transferring of the know-how and experience of the L0 microcooling technology on the design of the SuperB beam pipe cooling system. - Design of the L0 system including the manifold/support/flanges system. - Looking forward  explore the two-phase convective thermal exchange with microchannel technology in order to optimize the efficiency.

28. 28 28F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Next mechanical/laboratory activity Manufacturing and finalization of the various carbon fiber module support (additive method) structure with minichannel technology. Manufacturing and finalization of the various ceramic support structure for L0 module with microchannel (further reduction of channel dimensions D h < 100  m) by laser ablation. Final goal: realize a full Layer 0 mechanical support with microchannel technology, cooled and tested at the T.F.D. testbench, to verify the FEA simulations. Investigate the integration of microcooling techniques on Si chips themselves.

29. 29 29F.Bosi, M.Massa, SuperB Meeting, Isola d’Elba, May 31, 2008 Conclusions We are developing in Pisa a minichannel cooling system that seems promising to solve the high thermal power requirement of the L0 SuperB experiment. A new T.F.D. facility, now in the setup phase @ Pisa, will be able to test experimentally all the developed manufactured prototypes. In the next months we are going to produce and test a fully functional L0 mechanical prototype, with manifold feeding flanges. We are going to demonstrate experimentally that a cooling system based on microchannels can be a viable solution to the thermal and structural problems of the L0 detector, matching the severe low mass requirements.