Operational experience and aging studies
on the CDF Run II Silicon Vertex Detectors
Benedetto Di Ruzza on behalf of the CDF II Silicon Operation Group
2nd International Conference on Technology and Instrumentation
in Particle Physics
Chicago June 8th – 14th 2011
OUTLINE
1)
The Tevatron
2)
The CDF II detector
3)
The CDF II silicon subdetectors
4)
Silicon aging studies
5)
Conclusions
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The Tevatron and the CDFII detector
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Fermilab accelerators chain
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The Tevatron
Bunches structure
Initial luminosity record: 4.05 x10+32 (cm-2 s-1)
Mean Pbar production efficiency: ~ 22 x10-6
Mean Pbar Accumulation rate: ~ 25x10+10 (hr-1)
BS=Beam sync ticks =132ns
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Available Pbars (10+10)
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Dose rate during beam dump
Clean abort
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Quench
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Dose rate during data taking
Dose rate
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Beam doses during data taking
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Beam condition during data taking
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The CDFII Detector
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The Silicon Detectors
(ISL)
L00
1 Layer
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The CDFII Silicon detectors
OVERVIEW
L00: Single-sided strips: “Narrows” (SGS Thomson and 2 Microns)
“Wides” (Hamamatsu).
SVX: Double-sided strips: Layers 0,1,3 (Hamamatsu) perpendicular strips,
Layers 2,4 (Micron) small angled strips.
ISL: Double-sided strips: (Hamamatsu+Micron) small angled strips
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The Silicon Detectors
<==
X-Y (r-phi) and Y-Z (r-z) views
Beam pipe
L00 detail
==> narrow sensors
wide sensors
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Cooling lines
carbon support
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The Silicon Detectors
SVXII detail:
3 barrels
5 layers
12 wedges
SVXII: the readout is
used in the trigger too
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The Silicon Detectors: ISL
ISL detail
ISL central
ISLforward:
(inner and external barrels)
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Radiation Field inside the detector
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Radiation damage
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Aging studies: variables of interest
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Depletion Voltage
M.Moll, PhD Thesis, (1992) UniHamburg;
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Depletion voltage Measurement
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Depletion Voltage study – Signal Vs. Bias
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Depletion Voltage study – Signal Vs. Bias
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Depletion Voltage Projections L00-L0
Prediction for
SVX-L0
Prediction for L00
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Very preliminary result on L00
Studies still ongoing
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Depletion Voltage study Noise Vs. Bias
GOOD: does not require beam time
BAD: not possible for single side strip or after inversion type
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Signal / Noise projection
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Not only the sensors are in a radiation
environment
VME crates
SY527
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Problems induced by trigger rates:
Wirebond Resonances:
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Other Operational Challenges
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Conclusions
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Back-up slides
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Measured Radiation Field
• Radiation field
measured with TLDs
outside the silicon
volume in 2002-2003.
• NIM A514 188 (2003)
• Bias current evolution
2002-2004 consistent
with this radiation dose
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Inversion point
(SGS Thomson)
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Silicon D.A.Q. for SVX II
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Evolution of Bias currents
(R. J. Tesarek et al. NSS 2003)
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Depletion Voltage
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Depletion Voltage Projection L1
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ISL cooling lines
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SVXII.
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Laser diode/photo diode
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ISL
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ISL
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Readout Chip Accounting
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END
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