Supervisors : Petra Riedler and Vito Manzari Many thanks to : Michele Morel, Michele Caselle, Andre...
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Transcript of Supervisors : Petra Riedler and Vito Manzari Many thanks to : Michele Morel, Michele Caselle, Andre...
Supervisors : Petra Riedler and Vito Manzari
Many thanks to : Michele Morel, Michele Caselle, Andre Augustinus, Cesar Torcato De Matos
CHARLES Gabriel
OPERATING CONDITIONS OF ALICE SILICON PIXEL DETECTOR
Outline
Operating conditions of ALICE SPD
Humidity effect on half-staves
Dew point in the ALICE cavern
1/8
Half-staves in ALICE
Measurements in laboratory
(1)
2/81) Dew point
What is the dew point ?
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.
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.
10 28Dewpoint (°C)
Summer Student perception
Too dry(one drink is
needed, at least)
Perfect(drink is not necessary, but it is the perfect weather for
a drink at resto 1)
Uncomfortable
(best case : drink is compulsory)
1) Dew point
3/8ALICE and the Dew point
The difference decreases since March
How can it be explained ?
Difference between ambient temperature and dewpoint decreases from 12°C to 7°C
Cavern dew point follows the outside trend
But… it is just in average
(3)
1) Dew point
4/8ALICE and the Dew point
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.
How is the heart of ALICE ? 5/82) Humidity effects
I(V) curves
6 curves for each sector of one side. 10 sectors, 2 sides so 120 curves.
a. In ALICE
No general trend and no important change
Lab-tests ? 6/82) Humidity effects b. Lab-tests
Pictures
Noisy pixels
I(V) curves Bus resistance
HS_143 bus pad HS_143 pixel pad
Conclusion 7/82) Humidity effects
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 half-stave 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.
1) Dew point
8/8References
(1) The ALICE experiment at the CERN LH. The ALICE Collaboration, K Aamodt et al 2008 JINST 3 S08002
(4) M. Balkanski and R.F. Wallis, Semiconductor Physics and Applications, Oxford University Press, reprinted 2007.
(3) Website for the Geneva temperatures : http://www.wunderground.com
FOR LISTENING
(2) Barenbrug, A.W.T., Psychometry and Psychometric Charts, 3rd Edition, Cape Town, S.A. : Cape and Transvaal Printers Ltd., 1974
The heart of the heart of ALICE
2) Humidity effects
Rout=43.6 cmLout=97.6 cm
SPD
SSD
SDD
9/8
Dew point2) Humidity effects
10/8