1. 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

2. 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 C
Casse, Liverpool, RD50

3. 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

4. Material budget

5. Eta-distribution

6. Possible solution
Combine functionality of
Powerleads
Cooling tubes
Mechanical support

7. „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

8. 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

9. 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

10. 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)

11. CMS Multistage Cooling System

12. CMS cooling system in USC55 zone CV
P. Tropea

13. 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.

14. +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

15. +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.

16. 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

17. 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

18. Front-end readout and control

19. 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

20. 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)

21. 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)

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

23. CO2 cooling power Alternative estimate:
Cooling power = massflow x Enthalpy
Max Enthalpy at -50°C = kJ/kgmol =224 J/g
Power = massflow x 224 J/g
Power of 100 kW = J/s requires a mass flow of /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

24. CO2 pumps LEWA Herbert Ott GmbH Leonberg, Germany,
Pumps up to 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)

25. 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?