August 15, 2019 FCAL Insert Design Meeting

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Revision as of 15:06, 19 August 2019 by Whitey (Talk | contribs) (Action items)

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Meeting Time and Place

Thursday August 15 3pm At Jefferson Lab, room TED 2504

Agenda

Minutes

  • Discussed overall geometry and decided 40x40 crystal plus 19 lead glass block layers surrounding the crystals covered a wide enough area. The attached layout shows the trajectory of the particles grazing the BCAL Media:Particle trajectory through BCAL.pdf . Adding additional layers around the this would mean we would have to buils a new support structure to accommodate. The 40x40 crystal stack requires the 1st lead glass stack to be shimmed 3-4mm to ensure we can easily convert to 32x32 if we do not have enough crystals or pmts.
  • Discussed the cabling and patch panel requirements for the crystal modules. A type similar to the ComCal was discussed but with smaller SHV connectors. It was decided to take a field trip into the FCAL darkroom to discuss.
  • Tungesten absorber can be supported by the rohacell and be 6 cm thick. Sasha will need to look at the total coverage or the absorber.
  • the IG110 Rohacell appears to be radiation hard (enough) and stiff enough. The density of 110 Kg/cubic meter should have a low impact on the physics.
  • The crystals should be moved back 2.5 cm (to 12.5 cm from US face)to be centered on the lead glass
  • We discussed the crystal modules and the mag shielding. We need to make the steel shield 6mm longer (if 2mm cookie used) to fit properly. We want to look at using silicone cookies instead of optical grease. Josh also would like to test this joint as well as the soldering of the brass straps to eliminate heat stress and failures.
  • We decided we should use aluminum shims for the stacking of the blocks.
  • Discussed cooling system using copper tubing brazed to the aluminum blocks vs. holes through the aluminum blocks with pipe thread connections. We will have to look at the heat transfer characteristics and the pros and cons of each including fabrication, installation and repairs. It was pointed out that the BCAL has 192 pipe thread fittings that have not leaked to date.
  • It was decided that the acryllic sheet monitoring system should be sufficient for the crystals.

Action items

  • Continue with 40x40 crystal design and 19 lead glass blocks surrounding them. Move the crystals down stream 2.5cm. (Keith)
  • Develop cooling design using those similar to BCAL. Keith to get with Josh Foyles to discuss pros and cons of each.
  • Develop monitoring system layout (Keith/Tim)
  • Go into the FCAL dark room to see layout and discuss cabling design for crystals (All)
  • Perform heat load calculations to define best cooling system (Tim)
  • Layout cabling system concept in 3D (Keith)
  • Cut down long steel shield for Josh to perform strap/cookie tests (Tim)
  • Get cookie samples for Josh to use (Tim)
  • Determine tungsten absorber coverage (Sasha)