A. Dierlamm, IEKP 1

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Irradiation with Protons -IQC Karlsruhe

• IEKP - Universität Karlsruhe (TH)

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Isochroncyclotron in Karlsruhe

• 26 MeV protons
• Frequency 33MeV
• Accessible within 2 days

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Irradiation Area

• Cooling with Nitrogen gas down to -50C
• Initial positioning by laser pointer
• Scanning with 1mm row steps (10cm/s)
• Used proton current 2 mA
• Irrad. of 120x120mm2 up to 1e14 p/cm2
  takes 20min

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During Irradiation ...
Cold box with proton beam spot on mylar window
Scanning speed up to 250 mm/s !
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Homogeneity of Scanning
Scan Area
Area of Interest
Autoradiography picture
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Fluence Estimation

• Beam current I in p/s
• Calculate ratio r of hits inside homogeneous
  area to total hits
• F I r t / Ahomogene
• Get time t for irradiation
• Adjust speed to have integer no. of scans

Teststructure
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Fluence Measurement

• Ni foils behind teststructures in homogeneous
  area
• Measure specific activity of 57Ni line with
  Ge-Spectrometer
• Extrapolation to activity at 3.77 days after
  irrad.(T1/2 35.6h 1.483 days t 2.14
  days)
• Calibration factor for 26 MeV protons19.28 kBq
  cm2 / mg mAh
• 1 mAh 22.5e15 protons

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Comparision
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Speed Calculation
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Current Control

• Beam current monitored during irradiation
• Data saved to disk
• On-line integration of current
• Beam and scanning automatically stopped if
  current out of limit (e.g. 10)
• Insert aperture to get more stable low current

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Biasing scheme

• After 10 years LHC we expect a current of upto
  1µA per strip at 1M? ? 1V potential at p-implant
• Bias of 1V during irrad. and both AC and
  biasring on ground gives 1V over diel.
• Used bias voltage for safety reasons (voltage
  drop in power lines) 12 V

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Next Irradiations

• Hybrid
• Optohybrid
• Module

• We will provide the hybrids with power,
  clock, I2C-pulses and reset.
• The module will be under bias.