Workshop Ideas for cooling of a high granularity calorimeter Nick Lumb IPNLyon 02022015 Example ILD SDHCAL 1 m Max 30m Chambers are 1 m in width maximum length ID: 1041863
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1. High Granularity Calorimeter WorkshopIdeas for cooling of a high granularity calorimeterNick Lumb, IPN-Lyon02/02/2015
2. Example: ILD SD-HCAL1 mMax ~3.0mChambers are 1 m in width, maximum length 3 mEmbedded front-end Hardroc electronics cover the whole areaActive cooling essential!
3. Hardroc layout1000 mm300 mm12 x 12 matrix for SD-HCAL prototype → 144 Hardroc / m2For longest chambers in ILD design: 1m x 3m → 432 hardrocPower (no power-pulsing): ~10 W / m2 (1 mW/chan, 64 chans / hardroc)For longest ILD chambers: 30 W
4. SD-HCAL prototypeSS Absorber: 15mmGaps for cassettes: 13mmChamber + electronics: 6mmCassette: 2+3mm SS plates+ chamber + electronics = 11mm
5. Cooling pipe routing options‘In-chamber’ routingAttempt to make thermal contact between pipe and all Hardrocs (but difficult mechanically with present design!)Embed pipes in cassette coverCover thickness 2mm: very small pipe diameters‘In-absorber’ routingEmbed pipes in absorberConvective heat transfer in air gaps between Hardrocs and cassette, and cassette and absorbersLarger pipe diameters possibleCaveat: degredation of physics performance as diameters increase!Outside edge of absorber (between HCAL and criostat) or full circumference of absorberAs for ‘in-absorber’ routing, but much longer heat transfer paths through absorber to cooling pipe
6. ‘In-chamber’ cooling: possible pipe configurationsInInOutOutLongest pipe ~3mDisadvantage: many joints/weldsLength ~36mDisadvantage: high Δpx12x123m1m
7. Pressure drops for water and Li CO2Heat capacity: 4.18 J/g/KKinematic viscosity: 1.0 * 10-6 m2/sAssume ΔT of 2°CThen needed mass flow = 11 kg/hrΔP for 1 mm pipe ~175 barFor L = 3m, ΔP = 15 barGlobal assumptions:Pipe length = 36 m (single pipe option)Power to evacuate = 30 WHeat of vapourisation: 574 J/gKinematic viscosity: 0.1 * 10-6 m2/sNeeded mass flow = 0.25 kg/hrΔP for 1 mm pipe ~0.2 bar**Friedel methodWater (single phase)CO2 (two phase)Conclude: single pipe OK for CO2, water needs parallel pipes
8. Two-phase CO2 cooling2-Phase Accumulator Controlled Loop (2PACL)(NIKHEF)‘Accumulator’
9. CO2 cooling - Background in HEPAttractions:High latent heat (low flow) + low viscosity → Small ΔpSmall Δp → small pipe sizesSmall pipe sizes → low mass (good for tracking detectors, not so good for calorimeters!)High heat transfer coefficientRadiation hardLow global warming potentialDisadvantage: High pressures (60 bar at room temp), components expensiveRunning systemsAMS tracker (150 W)LHC-b VELO vertex detector (2x 750W)CMS pixel Phase 1 upgrade (2x 15 kW, system fully tested)Proposed for: CMS and ATLAS silicon trackers
10. 1 kW Test system at IPN-LyonAccumulatorPumpHEX-30-40~2.5 hoursDeveloped for CMS Phase-2 TK testingOperation at -30°CCould also operate at, say, 20°C→ Test-bed for HCAL system?(Pipe diam. 1.4 mm)T spread from Δp along 5.5 m pipe
11. Proposed CMS Phase-2 TK endcap cooling circuitsExample for 1 sector: 28 different types!Version for SD-HCAL could be simplerBut smaller pipes: 1mm instead of 3 mm – bending may still be a challenge!
12. SD-HCAL prototype: air coolingNot very effective!Chamber currentsunacceptably high
13. SD-HCAL prototype: water coolingCopper pipe brazed to copper platePlate held in contact with absorber sidesThermal contact not optimisedOne on each side of SD-HCAL prototype(Université catholique de Louvain)Inside temperature no cooling: ~50°CInside temperature with cooling: ~20°CChamber currents no cooling: ~100 μAChamber currents with cooling: ~1 μA
14. ConclusionsVarious options exist for the cooling of a high granularity calorimeter:Single-phase liquid cooling at the periphery of the absorbersSingle-phase cooling, pipes embedded in absorbersTwo-phase CO2 cooling, pipes embedded in chamber cassettesInfrastructure for two-phase CO2 tests available at IPN-LyonExperience with SD-HCAL prototype indicates that single-phase (water) cooling at the absorber edge may be sufficient, to be verified:Could build prototype cooling more readily adaptable to full HCALFinite element simulations