A Common Gel Defect

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A Common Gel Defect

• Crazing,...

Here seen along a length of the MuMetal
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RTV Gels

• GE 6156 has been the baseline gel since Amanda.
• Not sold as an optical Gel
• Color is uncontrolled
• Processing controversial
• 50.00/DOM
• Dow Corning Q3-6575 is being considered as an
  alternate.
• Unmixed samples have all been water clear.
• Dow Corning processes their electronic grade
  silicones differently to decrease the level of
  volatile materials. Observed out-gassing
  behavior is much less active.
• 30.00 to 40.00/DOM Depending on packaging.

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Requirements

• Optical/Mechanical coupling of PMT to Benthos
  Sphere
• Greater than 10 transmission at 300 nm
• 50 transmission at lambda lt 325 nm
• 85 or better transmission at 350 nm
• Must not scintillate or fluoresce (300nm lt lambda
  lt 600nm).
• Must tolerate temperatures from 70C to 45C with
  no more than 2 loss of room temperature
  transmission.Perhaps two GEL types, one for
  IceTop, one for In-Ice?

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Comparative Tests

• Optical transmission
• Cary (Varian) 300 Scan UV-Visible
  Spectrophotometer
• Stiffness, Depth(Force,Temperature)
• MOHR DIGI-TEST Fruit Quality Testing System,
  (yes fruit)
• Visual Inspection (Before and after FAT)
• Blue eyes

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Plastic vs Quartz Cuvettes
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GE, 7 Samples from Production
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GEL Comparison in plastic
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GEL Comparison in Quartz
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Gel Stiffness Data

• Both Gels mixed at production ratio 11.08 A to B

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Visual Inspection

• FAT 1 of 96 DOMs
• 3 Crazing Improved
• 13 New Crazing Appeared, (Minor)
• FAT 2 Data Collected and unavailable

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Dow Corning Gels to Consider

• Q3-6575 as shown in previous slides.
• Five DOMs in FAT 2
• Three Degass methods Mix AB degass 20 minuets.
• 75 torr Bubbles, 25 torr Perfect, 7.5 torr
  Perfect.
• FAT Data?
• Q3-6646 Highly purified version of Q3-6575
• One DOM in FAT 3, No Data Yet
• Q3-4154 Less Pt catalyst for clarity. (-45C)
• Q3-6679 Fluorogel Good to -70C, (expensive)
• Other

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GE verses Dow Corning

• GE
• Quality perception low
• Unwilling to provide information
• Dow Corning
• Provides 100 Raw Material for GELs Worldwide.
• Responsive with samples, and technical
  assistance.
• Willing to tweak standard GELs, or Develop New.
• Distributor authorized to repackage.
• Prices lower or competitive.