1. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Experience from CMS tracker cooling: Tracker Outer Barrel (TOB) Antti Onnela TOB Project Engineer, CERN-PH-DT2 A few words on CMS Tracker and its cooling Details of the TOB cooling

2. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB CMS Tracker services routed around solenoid magnet and along the central Wheel 0

3. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB CMS Tracker 5.4 m 2,4 m End Caps – TEC (at the two ends, one shown only) Inner Barrel & Disks - TIB & TID - Outer Barrel - TOB - Pixel detector Support Tube & Thermal Screen 24.4m3 closed volume operating temperature –10C 210 m2 of silicon sensors 6,136 Thin detectors (1 sensor) 9,096 Thick detectors (2 sensors) 9,648,128 electronics channels Beam pipe

4. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB CMS Tracker (Silicon strip) TOB: 5’208 x Tracker all: 15’232 x + control electr. + optical links + cables  15 kW  50 kW

5. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Tracker Cooling n Remove heat-load, maintain sensors at -10 ºC, but no heat/cold load to other CMS sub-systems (ECAL especially !) n Liquid-phase C 6 F 14 Fluid temperature: (+10 ºC) … -20 ºC … (-30 ºC)Fluid temperature: (+10 ºC) … -20 ºC … (-30 ºC) Fluid pressure: < 2 bar (pixels), < 6 bar (strip)Fluid pressure: < 2 bar (pixels), < 6 bar (strip) Cooling units in UXC balconiesCooling units in UXC balconies Cooled by salt-water (brine) at -45 ºC from USCCooled by salt-water (brine) at -45 ºC from USC

6. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Tracker Cooling n Active thermal screen, thickness 13 mm, next to Support Tube Cold panels in aluminium (2 sheets of 0.7 mm each, hot-roll bonded)Cold panels in aluminium (2 sheets of 0.7 mm each, hot-roll bonded) 10 mm of Rohacell foam insulation10 mm of Rohacell foam insulation Heating foils in Kapton/InconelHeating foils in Kapton/Inconel n At Tube ends only “passive” elements (honey-comb end- plates, cable/connector volumes) n Dry N2 flushing in every TK sub-detector, TK end- region and in patch-panels (?) inside CMS N2 fed to the TK volume along thermal screen cooling pipes, which are always at “Tracker temperature”N2 fed to the TK volume along thermal screen cooling pipes, which are always at “Tracker temperature”

7. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Tracker Cooling n Materials used in the cooling pipework (a lot of history…): Feed-pipes: soft copperFeed-pipes: soft copper –Brazed and solderered connections, double O-ring fittings at Tracker ends Pixel: Aluminium, rubber hoses (replacing possible)Pixel: Aluminium, rubber hoses (replacing possible) TIB/TID: Aluminium,TIB/TID: Aluminium, –welded joints, compression fittings TEC: Titanium in petals, manifolds in stainless steel,TEC: Titanium in petals, manifolds in stainless steel, –welded joints, compression fittings TOB: Copper-nickelTOB: Copper-nickel –Brazed and soft soldered joints with brass connections

8. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB TOB Support Wheel 4 Disks with 344 openings 6 joining Cylinders “Rods” With 6 or 12 modules 688 x

9. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB TOB Rod

10. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB TOB Rod Frame 113 pieces / rod frame 760 rod frames in total (688 needed + 72 spares) = 85880 pieces in total ! Capillary glued in jigs at RT

11. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Modules on the Rod Carbon-fibre (Mitsubishi K13D2U) / Cyanate-ester (YLA CE3) support frame with aluminium contact plates attached against 4 module supports Module supports in contact with cooling pipe

12. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Module supports and pipe Copper-nickel 70/30 pipe (Ø2.2 mm or Ø2.2 mm, 0.1 mm wall) A groove in the module support insert and a cap enclose the pipe. Capillar glue (Araldite 2020) injected, but pipe treated with mold-release to allow pipe to slide inside this “tube”.

13. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Testing modules and rods From testing of single and double modules to testing of complete rods n Tests performed in –20 °C. n  Tmax = 10 °C between silicon and coolant – OK ! n Equal cooling in all module positions along the rod. n Reliable testing is not simple ! Modules have excellent heat exchange with sourrounding volume.

14. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Soldered connections A test-set of soldered connections. Leak-tightness tested to 15 bar pressure, and thermal cycling down to -196  C. Copper-nickel 70/30 pipes and brass connection pieces Soldered with eutectic Sn62% - Pb36% -Ag2% with rosin flux (ERSIN 362)

15. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Test connections WITHOUT soldering Custom-made quick-connects

16. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Production: Leak testing of rod pipes “Bubble test” of bent and soldered rod pipes with water and 20 bar air  10 % of the 850 pipes produced leaked ! All leaks in the pipe wall (well known problem in Atlas…)

17. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Production: Leak testing of complete rods Helium leak-detector, test in vacuum mode. Alarm limit 10^-8 mbarl/s (bubble-test at best ~ 10^-5 mbarl/s). Only ~ 1% of pipes found now leaking, even if tighter test and rods gone through all production chain, thermal cycling, transports, etc. Leak repair by soldering.

18. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Relevance of the Leaks ? n Correspondence between Helium leak and C 6 F 14 leak studied using final type rod pipes with leaks spotted with He-test [Erkki Anttila, Helsinki Institute of Physics ]

19. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Relevance of the Leaks ? He leak size Loss of PF-5060 [g/a][ml/a] > 10 -3 mbarl/s18701113 10 -4 mbarl/s10563 4 x 10 -5 mbarl/s1811 < 10 -10 mbarl/s85 Bubble-test can spot leaks down to ~10 g/a scale. With He testing (1000-100’000x more sensitive) drop to insignificant leak levels for fluid loss. However tiny leaks can be signs of weak-spots, e.g. in solder joints, and need to take serious for long operation. Additional tests planned to verify results, and eliminate test system leaks. Additional tests planned to verify results, and eliminate test system leaks.

20. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Coolant distribution Distribution pipes of all 6 layers serving the 22 cooling segments

21. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB The work-site

22. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Manifolds

23. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Manifolds

24. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Soldering to the manifolds Fume extraction Small amount of solder in the iron tip to improve thermal contact Humid foam (not visible here) to cool/protect earlier Rod pipe solder and glues Lessons: Good local fume extraction is enough, no need for protection foil Requires stable hands, not for everybody! Brass connection pieces which were previously brazed were such oxidized than normal cleaning was not enough. Need to mechanically clean the surfaces for subsequent soft soldering.

25. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Experiences n Liquid-phase fluorocarbon cooling: Simple and easily manageable for design and production in multi-sitesSimple and easily manageable for design and production in multi-sites Adequate cooling performance for the modest power densities in the CMS silicon strip detectorsAdequate cooling performance for the modest power densities in the CMS silicon strip detectors Heavy, but with ~2 mm diameter pipes really significant only at the manifold areasHeavy, but with ~2 mm diameter pipes really significant only at the manifold areas Main problem: Operation temp below dew point leads to difficulties in the thermal management and insulation of the feeding pipes outside the well-controlled (dry) tracking volumeMain problem: Operation temp below dew point leads to difficulties in the thermal management and insulation of the feeding pipes outside the well-controlled (dry) tracking volume Can be used for the cooling of the cables, but making this to really function correctly is not obvious due different running conditions of the detectorCan be used for the cooling of the cables, but making this to really function correctly is not obvious due different running conditions of the detector

26. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Experiences n Copper-nickel + brass + soldered joints: One real problem: quality of the thin-wall CuNi pipesOne real problem: quality of the thin-wall CuNi pipes Another worry: activation of silver (in solder)Another worry: activation of silver (in solder) Soldering, even in-situ, works ok (need tools and methods), surfaces must be correctly prepared !Soldering, even in-situ, works ok (need tools and methods), surfaces must be correctly prepared ! Easy soldering yields also possibility to repair, and simple electrical connectionsEasy soldering yields also possibility to repair, and simple electrical connections n Leak-testing Absolutely necessary, and should be thought and tried in advance before productionAbsolutely necessary, and should be thought and tried in advance before production Bubble-test ok for coarse QC, but rather slow and operator dependantBubble-test ok for coarse QC, but rather slow and operator dependant Happy with He –leak testing: simple to use, high-precision (very small leak-sizes, precise localization of leaks)Happy with He –leak testing: simple to use, high-precision (very small leak-sizes, precise localization of leaks)

27. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Experiences n Operational experience … very soon !

28. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB SPARE SLIDES:

29. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Soldering Unexpected difficulties with the soldering: Brass connection pieces more oxidized and dirty than what we were used to. These pieces have now a longer history. → Need to prepare the surfaces more carefully, before having the pieces in the Wheel. Taken now into account in the planning for final assembly.

30. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Soldering 35 mm Clean Alu foil on other side Silicon module on one side

31. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Unsoldering Pipe removal can also be done without cutting the connection pipe, but this way the unsoldering is simpler.

32. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Leak testing Three weak solderings found with 10^-4 - 10^-6 mbarl/s leaks (all amongst first solder joints made). Connections disconnected, cleaned and resoldered: All connections then leak tight (alarm limit at 1x10^-7 mbarl/s)

33. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Testing of a segment A complete TOB cooling segment with 19 “rods” installed and tested in the tracker cold-room n Tests in room temperature and –25 °C. n Successful and simple filling and draining. n Equal cooling performance in all parallel rods. n Δp in segment (2.4 bar) higher than calculated (1.7 bar) Local pressure drops in manifoldsLocal pressure drops in manifolds 12 m

34. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Coolant distribution measured with a final cooling segment in the TOB Uniform temperature profile → equal distribution of coolant to all rods.

35. Atlas Tracker Thermal Management Workshop, 5.9.2006, A. Onnela, CERN Coolingof CMS TOB Thermal cycling n ALL rods pass through thermal cycling Several cycles between RT and -20CSeveral cycles between RT and -20C Detectors biasedDetectors biased n Modified commercial chest freezer, max 8 rods at a time [by Paul Tipton, Univ. of Rochester]