Optimized design for an sLHC Silicon tracker Outline: Requirements for sLHC trackers (massless and zero leakage currents) Reduce material budget by combining cooling pipe mechanical support current leads into single tube 3. Research needed

Sufficient signal, but need efficient cooling to avoid large Charge collection efficiency vs fluence for irradiated micro-strip detectors Sufficient signal, but need efficient cooling to avoid large leakage currents (-30 0C) CO2 efficient to -45 0C Casse, Liverpool, RD50

Material budget NOT BY SENSOR Material budget strongly driven by Large Power Dissipation, and need for Efficient Cooling (~33kW) Large Current requirements (~20kA) NOT BY SENSOR

Material budget

Eta-distribution

Possible solution Combine functionality of Powerleads Cooling tubes Mechanical support

„Novel“ connection scheme Connections between readout strip and chip are routed in an additional metal layer on the sensor  No Pitch Adapter necessary! Readout chips are directly bump bonded to the sensor ”No” Hybrid necessary! Supply lines for chips are provided by small Kapton glued (Maybe even with routing on sensor to sensor) Influence of 2nd Metal Layer: Increased capacitance and resistance of each sensor channel  Noise scales with capacitance Crosstalk caused by capacitive coupling between routing line and strips Thx Thomas Bergauer

1. How could a module look like? Basic ideas 1. How could a module look like? Optical fiber Cooling pipes = support =current leads Control lines on kapton Trigger Strixels connected via double metal layer to readout CFC with high thermal conductivity between sensor and hybrid to a) avoid heating of sensor by hybrid b) efficient heat transfer to cooling c) support for FR4 flex hybrid CFC CO2 Note: no thermal stresses, since module moves with cooling tube HV Si Hybrid CFC

Service Electronics, Trigger Lamp shape layers Service Electronics, Trigger Efficient CO2 cooling allows long cooling tubes. If bent in “lamp” shape with all connections and service in corners-> minimal material budget

Advantages of CO2 cooling 1. CO2 has large latent heat of evaporation 2. Non-toxic, non-flammable, industrial standard 3. Liquid at room temperature 300 liquid/vapour phase from -50 to +31 0C (for p=7 to 73 bar) If rupture disc breaks-> CO2 SNOW, not liquid! (as fire extinguisher)

CMS Multistage Cooling System

CMS cooling system in USC55 zone CV P. Tropea

2. How thick cooling pipes needed for 130 bar? Basic ideas 2. How thick cooling pipes needed for 130 bar? P = 1968x thickness/Diameter = 328 bar for Al (D=6 mm , thick 1mm) =328 bar for Al (D=1 mm, thick 160 um) =196 bar for Al (D=5mm, thick 500 um) P = pressure Bar da = outer diameterr in mm sv = wall thickness in mm vN = welding factor = 1,0 σ zul = elasticity, N/mm2 (110 for Al and Cu/Ni, 140 for steel , 33 annealed soft Cu) 2a. What is radiation thickness of Al tube with D=6mm, 1mm thick? Smeared on 10x10 cm sensor: 0.35% X0 To be compared with 2 Si sensors of 300 um: 0.7% X0 Al cooling tubes themselves do not add much to material budget! Or even Cu/Ni cooling tubes (easier to handle) could be acceptable (2.2% X0). Also smaller tube sizes possible.

+V V+Δ V 0 - Δ V 0 V Basic ideas 3. Can one use cooling pipes as current leads? 40 APV6 hybrids = 100 A Voltage drop in 2m Al tube of 6mm, 1mm thick=0.3V for 100 A BUT voltage drops cancel out if return line has same properties!!! V+Δ V +V 0 - Δ V 0 V

+V -V Basic ideas 4. Possible to integrate with present services? The cooling loops have to have inlet and outlet on the same side, but the current has to flow in the same direction (to get voltage drop compensation). This can be achieved by connecting manifolds of a given sector on one side to +V and the other side to ground. The current is indicated by the red arrows.

Si Basic ideas 5. Overall stability? Tubes should probably be mounted on two half shells or rings of CFC with holes for screwing the modules on the pipes (on both sides of half shell) Si cooling pipes

What happens if one module fails? Use programmable solid state fuse on each module (standard in space electronics) Measures current in each module and can switch on/off modules independently To keep same current in each current lead, bypass resistor could be switched on, if one module has to be switched off. SSF R

Front-end readout and control

Conclusion sofar 5 mm tubes seem to match SIMULTANEOUSLY very well requirements of: Cooling tube with small amount of material and high pressure allowed Current lead with good cooling and small voltage drop (also cancels) Mechanically strong enough to help in support structure

LHC-b cooling scheme Great features: no active elements like heaters or valves inside detector standard CO2 pumps standard primary chiller Temperature of whole system controlled by only ONE parameter: the vapor pressure in accumulator (increased by heater, decreased by chiller)

Required cooling power Cooling: assume 10W/module (now 3W). (Can get more current by voltage converter near patch panel) From patch panel: 2 m cooling tube = 40 modules =400 W = 400 J/s = 1.8 g/s evaporates. (Liquid enthalpy 223 J/g at 220 K, 700 kPa) Volume of 4mm ID tube = 3.14 x 4^2 x2000 mm^3 = 100 cm^3 = Pump: 10 m^3/h = 10000l/h = 3l/s = 3000 cm^3/s Assuming at most 60% evaporates. Then single line: 3g/s cools 40x0.1x0.1= 0.4 m2 Need 200 m2 = (200/0.4)x3g/s=1500g/s =1.3 l/s= 1.3x3600 l/h = 4700 l /h = 5 m3/h (This corresponds to 200/0.4 x 400 W = 200 kW cooling power)

CO2 cooling power Input Mixture Average mixture critical properties Carbon Dioxide, CO2 : 1.00000000 Average mixture critical properties critical compressibility : 0.274 critical density : 10.650 kgmol/m3 critical pressure : 7380.000 kPa critical temperature : 304.100 K normal freezing point : 216.600 K Mixture properties at 220 K and 700 kPa material phase is 0.00 mole % vapor vapor density : 0.425 kgmole/m3 liquid density : 25.972 kgmole/m3 vapor enthalpy : 5444.364 kJ/kgmol l iquid enthalpy : -9846.740 kJ/kgmol vapor heat capacity : 37.428 kJ/kgmol-K liquid heat capacity : 80.522 kJ/kgmol-K feed molecular weight : 44.010 kg/kgmol vapor molecular weight : 44.010 kg/kgmol liquid molecular weight : 44.010 kg/kgmol 1kgmol=44 g Density=25.97x44=1.14g/cm^3

CO2 cooling power Alternative estimate: Cooling power = massflow x Enthalpy Max Enthalpy at -50°C = 9846.740 kJ/kgmol =224 J/g Power = massflow x 224 J/g Power of 100 kW = 100000 J/s requires a mass flow of 100000/224 = 446 g/s = 446/1.14 cm 3 /s = 391 cm 3 /s = 1.4 m 3 /h Or by 60% evaporation: 2.3 m3/h Or by 200 kW: 5 m 3 /h

CO2 pumps LEWA Herbert Ott GmbH Leonberg, Germany, Pumps up to 100 000 l/h available. (used for gas bottle filling, CO2 liquifying (no cooling needed, just pressure) We need about 1000 l/h, i.e. a small pump (ca. 4 kEuro, including perfect membrane and leakage monitoring (used in health and food industry)

Research program Design and check flow of CO2 in various tubes and compare with theoretical estimates (help from CERN’s cryolab ? T. Niinikoski interested) Check cooling and powering of realistic modules Lamp shape feasible? How can new scheme be integrated in present CMS detector and using same services?