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Experience from CMS tracker cooling: Experience from CMS tracker cooling: Tracker Outer Barrel (TOB)Tracker Outer Barrel (TOB)

Antti OnnelaAntti OnnelaTOB Project Engineer, CERN-PH-DT2TOB Project Engineer, CERN-PH-DT2

A few words on CMS Tracker and its coolingA few words on CMS Tracker and its cooling

Details of the TOB coolingDetails of the TOB cooling

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CMS TOBCMS TOB CMSCMS

Tracker services routed around

solenoid magnet and along the

central Wheel 0

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CMS TOBCMS TOB CMS TrackerCMS 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 sensors6,136 Thin detectors (1 sensor)9,096 Thick detectors (2 sensors)9,648,128 electronics channels

Beam pipe

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CMS TOBCMS TOB CMS Tracker (Silicon strip)CMS Tracker (Silicon strip)

TOB: 5’208 x

Tracker all: 15’232 x

+ control electr. + optical links + cables

15 kW

50 kW

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CMS TOBCMS TOB Tracker CoolingTracker Cooling

Remove heat-load, maintain sensors at -10 ºC, but Remove heat-load, maintain sensors at -10 ºC, but no heat/cold load to other CMS sub-systems (ECAL no heat/cold load to other CMS sub-systems (ECAL especially !)especially !)

Liquid-phase CLiquid-phase C66FF14 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 USC Cooled by salt-water (brine) at -45 ºC from USC

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CMS TOBCMS TOB Tracker CoolingTracker Cooling

Active thermal screen, thickness 13 mm, next to Active thermal screen, thickness 13 mm, next to Support TubeSupport Tube• Cold panels in aluminium (2 sheets of 0.7 mm Cold panels in aluminium (2 sheets of 0.7 mm

each, hot-roll bonded)each, hot-roll bonded)• 10 mm of Rohacell foam insulation10 mm of Rohacell foam insulation• Heating foils in Kapton/InconelHeating foils in Kapton/Inconel

At Tube ends only “passive” elements (honey-At Tube ends only “passive” elements (honey-comb end-plates, cable/connector volumes)comb end-plates, cable/connector volumes)

Dry N2 flushing in every TK sub-detector, TK end-Dry N2 flushing in every TK sub-detector, TK end-region and in patch-panels (?) inside CMSregion and in patch-panels (?) inside CMS• N2 fed to the TK volume along thermal screen N2 fed to the TK volume along thermal screen

cooling pipes, which are always at “Tracker cooling pipes, which are always at “Tracker temperature”temperature”

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CMS TOBCMS TOB Tracker CoolingTracker Cooling

Materials used in the cooling pipework (a lot of Materials used in the cooling pipework (a lot of history…):history…):• Feed-pipes: soft copperFeed-pipes: soft copper

– Brazed and solderered connections, double O-ring fittings Brazed and solderered connections, double O-ring fittings at Tracker endsat Tracker ends

• Pixel: Aluminium, rubber hoses (replacing possible)Pixel: Aluminium, rubber hoses (replacing possible)• TIB/TID: Aluminium, TIB/TID: Aluminium,

– welded joints, compression fittingswelded joints, compression fittings

• TEC: Titanium in petals, manifolds in stainless TEC: Titanium in petals, manifolds in stainless steel, steel, – welded joints, compression fittingswelded joints, compression fittings

• TOB: Copper-nickelTOB: Copper-nickel– Brazed and soft soldered joints with brass connectionsBrazed and soft soldered joints with brass connections

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CMS TOBCMS TOB TOBTOB

Support Wheel• 4 Disks with 344 openings• 6 joining Cylinders

“Rods”• With 6 or 12 modules• 688 x

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CMS TOBCMS TOB TOB RodTOB Rod

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CMS TOBCMS TOB TOB Rod FrameTOB 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

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CMS TOBCMS TOB Modules on the RodModules 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

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CoolingCoolingofof

CMS TOBCMS TOB Module supports and pipeModule 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”.

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CoolingCoolingofof

CMS TOBCMS TOB Testing modules and rodsTesting modules and rods

From testing of single and double modulesFrom testing of single and double modulesto testing of complete rodsto testing of complete rods

Tests performed in –20 °C.Tests performed in –20 °C. Tmax = 10 °C between silicon and coolant – OK !Tmax = 10 °C between silicon and coolant – OK ! Equal cooling in all module positions along the rod.Equal cooling in all module positions along the rod. Reliable testing is not simple ! Modules have excellent heat Reliable testing is not simple ! Modules have excellent heat

exchange with sourrounding volume.exchange with sourrounding volume.

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CMS TOBCMS TOB Soldered connectionsSoldered connections

A test-set of soldered connections.Leak-tightness tested to 15 bar pressure, and thermal cycling down to -196C.

Copper-nickel 70/30 pipes and brass connection piecesSoldered with eutectic Sn62% - Pb36% -Ag2% with rosin flux (ERSIN 362)

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CMS TOBCMS TOB Test connections WITHOUT solderingTest connections WITHOUT soldering

Custom-made Custom-made quick-connectsquick-connects

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CMS TOBCMS TOB Production: Leak testing of rod pipesProduction: Leak testing of rod pipes

“Bubble test” of bent and soldered rod pipeswith water and 20 bar air 10 % of the 850 pipes produced leaked ! All leaks in the pipe wall (well known problem in Atlas…)

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CMS TOBCMS TOB Production: Leak testing of complete rodsProduction: 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.

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CMS TOBCMS TOB Relevance of the Leaks ?Relevance of the Leaks ?

Correspondence between Helium leak and CCorrespondence between Helium leak and C66FF1414 leak leak studied using final type rod pipes with leaks spotted studied using final type rod pipes with leaks spotted with He-test [Erkki Anttila, Helsinki Institute of Physics ]with He-test [Erkki Anttila, Helsinki Institute of Physics ]

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CMS TOBCMS TOB Relevance of the Leaks ?Relevance of the Leaks ?

Leak He vs. PF-5060

y = 5,41x

y = 0,29x

y = 0,05x

y = 0,03x0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

16,0

18,0

20,0

0,0 5,0 10,0 15,0 20,0 25,0

t [days]

m [

g]

He >10^-3 mbarl/s

He 10^-4 mbarl/s

He 4x10^-5 mbarl/s

Leakless

Linear (He >10^-3 mbarl/s)

Linear (He 10^-4 mbarl/s)

Linear (He 4x10^-5 mbarl/s)

Linear (Leakless)

He leak sizeLoss of PF-5060

[g/a] [ml/a]

> 10-3 mbarl/s 1870 1113

10-4 mbarl/s 105 63

4 x 10-5 mbarl/s 18 11

< 10-10 mbarl/s 8 5

Bubble-test can spot leaks down to ~10 g/a scale. With He testing (1000-100’000x 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 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.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.

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CMS TOBCMS TOB Coolant distributionCoolant distribution

Distribution pipes of all 6 layers

serving the 22 cooling segments

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CMS TOBCMS TOB The work-siteThe work-site

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CMS TOBCMS TOB ManifoldsManifolds

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CMS TOBCMS TOB ManifoldsManifolds

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CMS TOBCMS TOB Soldering to the manifoldsSoldering to the manifolds

Fume extraction

Small amount of solderin 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.

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CMS TOBCMS TOB ExperiencesExperiences

Liquid-phase fluorocarbon cooling:Liquid-phase fluorocarbon cooling:• Simple and easily manageable for design and production Simple and easily manageable for design and production

in multi-sitesin multi-sites• Adequate cooling performance for the modest power Adequate cooling performance for the modest power

densities in the CMS silicon strip detectorsdensities in the CMS silicon strip detectors• Heavy, but with ~2 mm diameter pipes really significant Heavy, but with ~2 mm diameter pipes really significant

only at the manifold areasonly at the manifold areas• Main problem: Operation temp below dew point leads to Main problem: Operation temp below dew point leads to

difficulties in the thermal management and insulation of difficulties in the thermal management and insulation of the feeding pipes outside the well-controlled (dry) the feeding pipes outside the well-controlled (dry) tracking volumetracking volume

• Can be used for the cooling of the cables, but making this Can be used for the cooling of the cables, but making this to really function correctly is not obvious due different to really function correctly is not obvious due different running conditions of the detectorrunning conditions of the detector

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CMS TOBCMS TOB ExperiencesExperiences

Copper-nickel + brass + soldered joints: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), Soldering, even in-situ, works ok (need tools and methods),

surfaces must be correctly prepared !surfaces must be correctly prepared !• Easy soldering yields also possibility to repair, and simple Easy soldering yields also possibility to repair, and simple

electrical connectionselectrical connections Leak-testingLeak-testing

• Absolutely necessary, and should be thought and tried in Absolutely necessary, and should be thought and tried in advance before production advance before production

• Bubble-test ok for coarse QC, but rather slow and operator Bubble-test ok for coarse QC, but rather slow and operator dependantdependant

• Happy with He –leak testing: simple to use, high-precision Happy with He –leak testing: simple to use, high-precision (very small leak-sizes, precise localization of leaks)(very small leak-sizes, precise localization of leaks)

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CMS TOBCMS TOB ExperiencesExperiences

Operational experience … very soon !Operational experience … very soon !

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CMS TOBCMS TOB SPARE SLIDES:SPARE SLIDES:

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CMS TOBCMS TOB SolderingSoldering

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.

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CMS TOBCMS TOB SolderingSoldering

35

mm

Clean Alu fo

il on oth

er side

Silicon module on one side

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CMS TOBCMS TOB UnsolderingUnsoldering

Pipe removal can also be done without cutting the connection pipe, but this way the unsoldering is

simpler.

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CMS TOBCMS TOB Leak testingLeak 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)

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5.9

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6, A

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CoolingCoolingofof

CMS TOBCMS TOB Testing of a segmentTesting of a segment

A complete TOB cooling segment with 19 “rods”A complete TOB cooling segment with 19 “rods”installed and tested in the tracker cold-roominstalled and tested in the tracker cold-room

Tests in room temperature and –25 °C.Tests in room temperature and –25 °C. Successful and simple filling and draining.Successful and simple filling and draining. Equal cooling performance in all parallel rods.Equal cooling performance in all parallel rods. ΔΔp in segment (2.4 bar) higher than calculated (1.7 bar)p in segment (2.4 bar) higher than calculated (1.7 bar)

• Local pressure drops in manifoldsLocal pressure drops in manifolds

12 m12 m

Atla

s T

rack

er T

herm

al M

anag

emen

t Wor

ksho

p, 5

.9.2

006,

A. O

nnel

a, C

ER

NA

tlas

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cker

The

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Man

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CoolingCoolingofof

CMS TOBCMS TOB

Coolant distribution Coolant distribution measured with a final cooling segment in the TOBmeasured with a final cooling segment in the TOB

CRack Cooling Unit: coolant temperature

5

10

15

20

25

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0

t / min

T /

°C

Temperature of rod input connection pipe

9

11

13

15

17

19

21

23

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Rod number

T /

°C

Tmin [°C] Tmax [°C]

Uniform temperature profile

→ equal distribution of coolant to all rods.

Atla

s T

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CMS TOBCMS TOB Thermal cyclingThermal cycling

ALL rods pass through thermal cyclingALL rods pass through thermal cycling• Several cycles between RT and -20CSeveral cycles between RT and -20C• Detectors biasedDetectors biased

Modified commercial chest freezer, Modified commercial chest freezer, max 8 rods at a timemax 8 rods at a time

[by Paul Tipton, Univ. of Rochester][by Paul Tipton, Univ. of Rochester]