Greg!!Hallewell!!hallewel@atlas.cern.ch!!CERN/Centre de Physique des Particules de Marseille!!EP Division, CERN, 1211 Geneva 23!! !! !!Switzerland!!ATLAS!!TRACK!!Grounding, shielding, cooling!!Fluorocarbon Evaporative Cooling Developments for the ATLAS pixel and Semiconductor Tracking Detectors!!990428012

G. Hallewell (CERN/CPPM), E. Anderssen (LBL), D. Bintinger (LBL),
M. Bosteels (CERN), P. Bouvier (U. Geneva), B. Payne (RAL), 
R. English (RAL), J. Godlewski (CERN/Crackow), B. Gorski (Crackow), 
S. Grohmann (CERN/Dresden),  T. Hayler (RAL), T.Jones (Liverpool), 
S. Lindsay (Melbourne), W. Miller (Hytec Inc., NM), 
T. Niinikoski (CERN), J. Olszowska (Crackow), E. Perrin (U. Geneva),
A. Pilling (RAL), H. Sandaker (CERN/Oslo), J. Thadome (Wuppertal),
V. Vacek (CERN, Czech Technical University, Prague)
!!
Fluorocarbon Evaporative Cooling Developments for the ATLAS pixel 
        and Semiconductor Tracking Detectors

We report on the development of evaporative fluorocarbon cooling 
for the ATLAS Pixel and Semiconductor Tracker (SCT) Detectors.

These detectors collectively dissipate around 50kW heat, which must 
removed from the inner detector cavity. For an operational 
lifetime of around 10 years in the high radiation field close to the 
LHC beam, the silicon substrates of the SCT and outer pixel layers 
must be kept at a temperature of below -6 deg C, with only short 
warm-up periods each year for maintenence.

The pixel B-physics layer is located at a radius of around 4.5 cm 
from the beams, and will require yearly replacement when LHC 
operates at full luminosity: it furthermore makes a particularly
severe requirement of small contribution of the cooling  services 
to the total inactive material budget in this tracking layer.
  
Coolant channels on the pixel and SCT detectors 
Cooling measurements on prototype pixel and SCT thermaostructures 
have been made using the following coolants, which are listed together
with their chemical formulae and saturated vapor pressure (svp) around
-15 deg C:

   per-fluoro-n-butane (C4F10),  480 mbar
   per-fluoro-n-propane (C3F8),  2.2 bar 
   trifluoro-iodo-methane (CF3I) 1.1 bar
  and custom mixtures of C4F10 and C3F8 with s.v.p around 1 bar


Temperature profiles long representative prototype SCT and 
pixel thermostructures have been measured under a range of
thermal laodHeat transfer
a very low mass 
cooling syetem  detectorssystemsFluorocarbon Evaporative Cooling Developments for the ATLAS pixel 
        and Semiconductor Tracking Detectors
!!
Fluorocarbon Evaporative Cooling Developments for the ATLAS pixel
             and Semiconductor Tracking Detectors.

G. Hallewell (CERN/CPPM), E. Anderssen (LBL), D. Bintinger (LBL),
M. Bosteels (CERN), P. Bouvier (U. Geneva), B. Payne (RAL), 
R. English (RAL), J. Godlewski (CERN/Crackow), B. Gorski (Crackow), 
S. Grohmann (CERN/Dresden),  T. Hayler (RAL), T.Jones (Liverpool), 
S. Lindsay (Melbourne), W. Miller (Hytec Inc., NM), 
T. Niinikoski (CERN), J. Olszowska (Crackow), E. Perrin (U. Geneva),
A. Pilling (RAL), H. Sandaker (CERN/Oslo), J. Thadome (Wuppertal),
V. Vacek (CERN, Czech Technical University, Prague)

We report on the development of evaporative fluorocarbon cooling 
for the ATLAS Pixel and Semiconductor Tracker Detectors.
Studies have been aimed at the implementation of a vety low mass 
cooling syetem  detectorssystemsFluorocarbon Evaporative Cooling Developments for the ATLAS pixel 
        and Semiconductor Tracking Detectors
!!