Speaker
MARCO ORIUNNO
(CERN)
Description
The Roman pots of the TOTEM experiment at LHC will be equipped with
edgeless silicon micro-strip detectors. Each of the 24 pots comprises an as-
sembly of 10 detector planes under vacuum and cooled at -15 deg C. The
thin
pot window made of stainless steel separates the secondary vacuum from
the
primary vacuum of the LHC accelerator. The detectors are mounted very
close (100μm) to this window. The required detector resolution is of the or-
der 20μm, the overall alignment precision has to be better than 30μm. The
detector planes are composed of a kapton hybrid PCB glued on a substrate
made of a so-called controlled expansion alloy, CE07 with 70% Si and 30%
Al.
An evaporative cooling system based on the fluorocarbon C3F8 with apecial
oil-free compressors placed in an accessible controlled area at 300 meters
from
the detectors have been choosed. The throttling of the fluid is done locally
through capillaries. Special effort in the integration resulted in a compact de-
tector arrangement inside the pot which allows to accomodate the
capillaries,
the evaporators and the cabling. A thermo-mechanical prototype has been
as-
sembled to measure the thermal performance and to optimize parameters
like
the length of the capillaries. The results fully match the requirements and
the
expectations of finite element calculations. They show a low thermal
gradient
on the cards ≤ 2 deg, an uniform temperature distribution over the 10
planes.
Author
MARCO ORIUNNO
(CERN)
