Irradiation of CMS Silicon sensors with fast neutrons

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Irradiation of CMS Silicon sensors with fast
neutrons
Presented by S. Assouak

• S. Assouak, E. Forton, G. Gregoire
• Institute of Physics, University of Louvain
• 1348-Louvain-la-Neuve- Belgium
• http//www.fynu.ucl.ac.be

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Outline
1. Introduction 2. CMS Silicon detector
overview 3. Neutron Irradiation production and
irradiation setup 4. Electrical
characterization 5. Typical results Comparison
before/after irradiation 6. Conclusion
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Introduction
Compact Muon Solenoid reconstruct particules
tracks
Large Hadrons Collider
running 10 years in a high luminosity
environment (Neutron fluence1014 n cm-2 )
Silicon Strip Detectors
must keep their physics performances
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CMS detector overview
P strips
30 000 Silicon strip detectors
lt100gt crystal lattice orientation
n-type substrate
Operating at - 10C
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Neutron irradiation in Louvain
9Be d n 10B
Neutron production
50 MeV ( 10µA ) deuteron beam on a 1-cm thick,
2-cm diameter Beryllium target
Average energy 20.4 MeV Contamination Gammas
lt 2.4 Charged particles lt
0.03
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Irradiation setup
Irradiation setup
LHC fluence reached in 10 h
Detectors to irradiate
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Electrical characterization
Probe station PA200 RH 2 Tchuck - 10C
LabView software GPIB control of instruments
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Results
Interstrip capacitance measurements
Strip ramp
Strip Scan
No changes after irradiation
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Other strip measurements
Unchanged after irradiation
80nA after irradiation
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Bulk measurements
Depletion Voltage
C-V Characteristic
Approximately the same depletion Voltage lt 200V
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Bulk measurements
Leakage current _at_ - 10 C
Ileak lt 5 nA
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Depletion Voltage after irradiation
After irradiation (1014 n/cm2)
Annealing _at_ 60C for 80 minutes
Depletion voltage decreases
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Leakage current annealing
Ileak much higher than before irradiation
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? parameter measurement
?? smaller than found in previous literature
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Conclusions
1. Neutron irradiation setup operating at CMS
conditions 2. Characterization setup developed
and operational

• discrepancy of ??? values with respect to
  literature

• Change of the effective doping concentration of
  the bulk

Variation on the depletion voltage and leakage
current
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Perspectives
1. Better annealing study foreseen soon 2.
Study of depletion voltage, leakage current and
other parameters with neutron fluence and energy
dependence 3. Comparison with the Hamburg model