Transcript Micro channels optical fibers - Indico

Micro –channel cooling systems
and optical fibre sensors
Why we need cooling in detectors?
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We need cooling to take out the heat produced by the detector, the electronics and the cables.
We need it to maintain a neutral environment for the optimal functioning of the electronics.
To guarantee a long detector lifetime.
To avoid over heating and damage or malfunctioning of the detectors.
We need the cooling to be cool ;)
Micro- Channels
Micro-channels are used in multiple
different experiments, notably NA62
and LHCb
 Micro-channels can cool the very heart
of detectors from very close due to
their extremely small size.
 Micro-channels are cooling units that
are used to cool down detectors
 They can be exploited not only with
liquid, but also with evaporative cooling
systems.
With thanks to Paola Tropea, Karl Gill, Giulia Romagnoli, Gaia Maria Berruti,
Anne Dabrowski, Archana Sharma
Why are microchannels
advantageous?
Fun mind-blowing facts
-the channels are about the size of your hair!
-They are extremely useful due to their small
size, radiation and magnetic resistance, and
their low material cost
-it is going to be used on new detectors
because of these advantageous properties:
 They are the same material as the
detectors( silicone) therefore they expand
and contract with heat at the same rate as
the detectors.
 They are very thin , therefore they
minimise the total mass of the detector,
reducing bias in data.
 They fit directly under the heat source,
and better distribute the cooling, in
contrast to cooling systems based on
piping, where the cooling is distributed
unevenly.
What are the dangers of heat and humidity?
 Heat could potentially melt and ruin the electronics, detectors and the data produced or in other words 100
million Swiss francs of machinery and ten years of work… LOST.
 Another danger which the wrong amount of heat could produce is the malfunctioning of most detectors which
would cause a lot of damage or unreliability concerning the data, or even no data at all.
 Humidity could produce short-circuits and bias the data, it could even destroy the experiments
Optical Fibre sensors
Heat sensor
Humidity sensor
 Optical fibre sensors are currently being used a lot in
CMS and are being proposed for most other experiments
at CERN .
 Optical fibres are so thin that they are perfect for
entering small areas in the detectors
 Optical fibre sensors work by sending light through the
fibre and a special grating inside the fibre called the
Bragg grating. The shape of the grating varies
depending on the temperature and pressure. Depending
on it’s shape, a certain quantity of light is reflected back.
This quantity varies depending on the heat and pressure
applied to the sensors. To detect humidity, we coat the
fibres in polyimide : a plastic that expands on contact
with water molecules (humidity). This expansion causes
pressure on the fibres, resulting in a stronger reflection
of light.
Why are optical
fibres
advantageous?
Fun mind-blowing facts:
-The optical fibres are approximately the size
of your hair, even with a protective coating
-They are relatively cheap because there can
be several detectors on one fibre
•1 fiber optic array with
•8 FBG-based hygrometers
(MULTIPLEXING
)
-It is extremely effective compared to the
old system because it can have multiple
detectors on one fibre compared to the old
system which used to have to include one
wire for each detector. Also , fibre optic is
faster than other electronic systems.
Lauren Gill
Nicolas Olney-Rainville
Alistair whistler
Maxime Barbier stage d’observation 05/02/2015