SDD status after playing one year
Emanuele Biolcati, Giacomo Ortona
December 13, 2010
1/9
Modules in acquisition during Pb-Pb runs
2/9
Summary from the last calibration in AliEn (run:139645)
*** Layer 3 ***
bad modules = 8
bad chips in good modules = 0
bad hybrids = 16
bad anodes in good hybrids = 712
fraction of bads (anodes+chips+mod) = 0.111793
*** Layer 4 ***
bad modules = 18
bad chips in good modules = 16
bad hybrids = 40
bad anodes in good hybrids = 798
fraction of bads (anodes+chips+mod) = 0.122492
*** Total ***
bad modules = 26
bad chips in good modules = 16
bad anodes in good modules+chips = 1510
fraction of bads (anodes+chips+mod) = 0.119035
3/9
Calibration in 2010: baseline, noise and gain
4/9
Bad anodes in 2010
Low points correspond to the exclusions of part of the detector from the acquisition.
During these periods no data have been taken.
More instability for the layer 3, due to the ladder 6 problems.
Maximum decrease of the fraction of good modules can be estimated at ≈3%.
5/9
Half modules with drift speed measured by injectors
Data taken during the switching on/off periods not shown.
6/9
Half modules with injectors - normalized to good modules
We normalized the half-module-w-injector number to the number of modules tagged as
GOOD by the PEDESTAL+PULSER runs.
Data have been fitted by a single line or two lines.
The layer 3 seems to have oscillation around the same value, the layer 4 seems to lose
injectors after July (maybe because Sergey finished his on-call period?).
7/9
About the injector dead rate
An optimistic (?) extrapolation about the future (from the linear fit) tells us that we can
measure drift speed using the injectors for ≈8 years. Is it enough?
Possibile reason for the injector lost can be the humidity decrease → under investigation.
8/9
Conclusion
SDD worked! During the pp and Pb-Pb runs, taking data without giving too many
problems to ALICE (as a respect to other detectors. . . :)
The “efficiency lost” is quite small and it remains under control via the calibration
runs.
First open task: the injector lost beahaviour → under investigation (proposal: a
SDD tool to monitor the humidity?)
Second open task: the LDC-16-19-0 very old to be updated → work in progress
This is my last presentation as SDD on-call. So I wish to thank
all the SDDers for the time spent togheter, the important results
obtained and everything I learned in this year at CERN.
Special thanks to Davide, Mario, Sergey and Francesco who
helped me a lot-lot-lot of times to avoid me to destroy the
detector.
Good luck to Giacomo will be here alone for the next six months!
Emanuele
9/9