Issues

1
Pixel Detector Radiation Length- Growing Issue

• Issues
• At ?gt1.9 radiation ranges from 25 to 35
• Large fraction of increase is due to support
  services
• Cooling service connections are a major factor,
  comprising upwards of 500 connections to bring
  the C3F8 fluid in and vapor out
• Coolant routing requires 80 inlets and 80 outlets
  of rigid aluminum tubing- must sustain 16bar
  proof pressure

2
New Directions for Inner Tracking Detectors

• Innovative solutions needed to
• Reduce coolant system complexity
• Eliminate over 160 pressure regulators required
  to hold temperatures constant
• Greatly reduce number of service connections,
  lowering mass and significantly improving system
  wide reliability
• Utilize coolant pipes are structural members
• Eliminate structural coupling of adjacent coolant
  tubes (bi-stave), providing improved dimensional
  stability
• Solution put forth is to develop C-C heat pipes
  for collecting heat from distributed sources
• Sealed two-phase fluid, passive, no pressure
  variations
• Provides conductivity 1000X of copper
• Tube can be integrated with structure.

3
Heat Pipe Application in Tracking Detectors

• Objective is to promote heat pipes in
  silicon-based charge particle detectors
• What is involved?
• Composite wall structure, low CTE matching shell
  structure
• Long evaporative section, short condenser section
• Selection of sealed vapor is ammonia, stable
  fluid in radiation environment
• Long life has been demonstrated, need similar
  experience with C-C tube
• Seal C-C with nickel, 2mil wall or possibly using
  Al wall

Groove wick, 31 total 0.3mm wide opening, 0.6mm
deep
4
Pixel Barrel Heat Pipe Example

• Highlights
• Simple manifold at each end of barrel
• Number of inlets chosen for redundancy, one path
  is sufficient
• Dual channel condenser, capable of handling high
  heat flux
• Hermeticity provided by step-up step-down module
  pattern.

5
What does it replace?