Transcript CHARLES Gabriel Supervisors : Petra Riedler and Vito Manzari Many thanks to : Michele Morel, Michele Caselle, Andre Augustinus, Cesar Torcato De.

CHARLES Gabriel
Supervisors : Petra Riedler and Vito Manzari
Many thanks to : Michele Morel, Michele Caselle, Andre Augustinus, Cesar Torcato De Matos
Outline
Operating conditions of ALICE SPD
Dew point in the ALICE cavern
Humidity effect on half-staves
Half-staves in ALICE
Measurements in laboratory
(1)
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What is the dew point ?
1) Dew point
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The relative humidity (RH) is defined as the ratio of the partial pressure of
water vapor compared to the saturated vapor pressure of water vapor at a
given temperature.
The dew point is the temperature at which the partial pressure of water vapor in
the air is equal to its pressure of saturated vapor. (2)
Example : at ambient temperature 20°C and a relative humidity of 60% the dew point is
12.01°C.
Summer Student perception
Too dry
Perfect
Uncomfortable
(one drink is needed, at
least)
(drink is not necessary, but it is the
perfect weather for a drink at resto 1)
(best case : drink is
compulsory)
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Dewpoint
(°C)
1) Dew point
ALICE and the Dew point
Difference between
ambient temperature and
dewpoint decreases from
12°C to 7°C
The difference decreases
since March
How can it be explained ?
Cavern dew point follows
the outside trend
But… it is just in average
(3)
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1) Dew point
ALICE and the Dew point
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The difference can
sometimes be as low as
about 4°C.
Conclusion : investigate the humidity effects will explain
the present and futur consequences of these operating
conditions on the detector.
2) Humidity effects
a. In ALICE
How is the heart of ALICE ?
I(V) curves
6 curves for each sector of one side. 10 sectors, 2 sides so 120 curves.
No general trend and no important change
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Lab-tests ?
2) Humidity effects
b. Lab-tests
Pictures
HS_143 bus pad
I(V) curves
Noisy pixels
HS_143 pixel pad
Bus resistance
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2) Humidity effects
Conclusion
There is no major change in the behavior of the detector since
the breakdown of the LHC. The operating conditions have not
affected the SPD. But for this kind of problem only long term
study makes sense.
There is not yet any change in the behavior of the tested halfstave in the laboratory. Maybe we see the begining of some trend.
So now we have to continue the lab-test, wait for some
change, or not and check if the same behavior is seen in
the ALICE SPD.
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1) Dew point
References
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(1) The ALICE experiment at the CERN LH. The ALICE Collaboration, K Aamodt
et al 2008 JINST 3 S08002
(2) Barenbrug, A.W.T., Psychometry and Psychometric Charts, 3rd Edition, Cape Town, S.A. :
Cape and Transvaal Printers Ltd., 1974
(3) Website for the Geneva temperatures : http://www.wunderground.com
(4) M. Balkanski and R.F.Wallis, Semiconductor Physics and Applications, Oxford University
Press, reprinted 2007.
FOR LISTENING
2) Humidity effects
The heart of the heart of ALICE
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SSD
SDD
SPD
Lout=97.6 cm
Rout=43.6 cm
2) Humidity effects
Dew point
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