Cz Analysis Status

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Cz Analysis Status
Alison Bates

A. Bates, P.Collins, D. Eckstein, J. Kennedy,
C.Parkes, J. Palacios
LHCb Week, Zurich, September 2003
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Overview

• Czochralski silicon introduction
• Detector description
• 2002 test beam
• Detector irradiation
• 2003 test beam -
• Successful data read out
• Quick 1st look at radiation hardness

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Czochralski Silicon

• Single crystal pulled out of melt
• (High resistivity available)
• Oxygen content
• Standard silicon 1e15cm-3
• DOFZ silicon 1e17cm-3
• Cz silicon 1e18cm-3
• Oxygen thought to increase radiation hardness

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Test beam detector

• Courtesy of Jaakko Harkonen Helsinki
  Institute of Physics
• Strip detector
• Pitch of 50 microns
• p on n Czochralski material
• Area read out 6.1 x 1.92 cm
• Strips run along x axis (6.1 cm)
• 2 working SCT128A chips readout

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2002 Test Beam Czochralski detector

• Test beam of 120 GeV/c muon pions
• Initially nice clear signals from detector

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Irradiations May 2003
Max. Dose 5 E14 1 MeV n. eq./cm2

• PS CERN- 24GeV protons
• Already bonded gt tricky mounting!
• From annealing studies, expected Vdep for DOFZ
  400V
• Irradiation Profile

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June 2003 Test Beam-initial look at results
167V Bias shown
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Cross-Bonding

• Double peak structure in Residuals

Detector pads
Fan-out pads

• Detector
• Cross-bonded
• -verified under microscope
• -Description updated

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More than cross-bonding

• Still doesnt solve residuals

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Double hits

• Correlation band
• Anti-correlations from Cross-bonding

• All S/Ngt3 hits
• Anti-correlations from Cross-bonding
• Largest hit/event
• Hits occur in pairs. Coupling to next DAQ channel

DAQ Channel
Track Intercept Position
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Charge only in higher DAQ channel

• Red charge leakage to higher DAQ channel
• Black lower channel

• Leakage to Next Neighbour

Hence, asymmetric,not a cross-coupling in fan-out
effect. Time related, chip/ADC ?
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Residuals

• Add into Clusters charge from next DAQ channel
• But dont change cluster position
• Start with highest ADC value

Not fully realigned yet.
400 um thick
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Simulation
Using ROSE (Hamburg) model With available
temperature measurements/estimates (ELMB problems)

• Float Zone Silicon
• Expect 1400 V full depletion

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Results(besides successful test beam data
taking!)

• S/N cut 6

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Conclusions

• None yet!.Detailed analysis just starting!
• Even at 5 years of LHC radiation environment
  still getting reconstructed clusters.
• Too early to conclude, but standard silicon would
  not deplete until 1400V
• Looks hopeful!