US CMS HCAL Meeting Boston University

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US CMS HCAL MeetingBoston University

• Vasken Hagopian
• Florida State University

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HPD QE K27 Spectrum
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Test Beam results
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QE x K27 Spectrum
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Conclusions

• The test beam measurements are not compatible
  with the QE of the HPDs.
• The HPD QE provided by DEP are not standard
  bi-alkali nor green extended bi-alkali.
• We need to find out what DEP is actually
  measuring.

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HB/HE LED and Laser

• From Test Beam at CERN in 2002
• Nichia blue LED barely excites K27 fluor.
• The LED light to HPD is mostly scattered blue
  light.
• Easy to correct so LED light to HPD should be
  very similar to megatile. Use green LED that is
  2.5 times brighter. (See K. Johnson talk).
• Green LED at 5 volt and 25 nsec should correspond
  to over 1 TeV.

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HB/HE LED and Laser

• Basic calibration module design is good.
• Laser distribution has been measured in the lab
  with splitters and the correct length of quartz
  fibers. Measurements with Pin Diodes and
  corrected for HPD.
• QE of Pin Diode 80, QE of HPD 10 with a gain
  of 2000.

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Laser system

• Laser to Calorimeter sector (e.g HB) to
  Calibration box to HPD.
• 337 nm UV. Pin1 25pC. Pin2 3pC, HPD 30 pC.
• 380 nm with dye laser. Pin1 50pC, Pin2 6pC,
  HPD 60 pC.
• UV laser to megatile 4 pC.
• Dye Laser to megatile 0.3 pC.

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Progress

• HB Calibration box on hold waiting for VECSEL
  connection determination. Most optical parts
  completed.
• HE Calibration box, first prototype under
  construction (just completed).
• HO Calibration box box dimensions not yet
  specified.