February 26, 2020 FCAL 2 Design Meeting

Meeting Time and Place =

Wednesday February 26, 11:00am At Jefferson Lab, room TED 2504

• Present - Sasha Somov, Josh Crafts, Eugene, Stephanie, Keith Harding, Tim, Fernando, Chris Stanislav

Agenda

• Initial design substantially complete
  • Drawing Package in check (most)
  • 3D Model complete (except details to be discussed below)
• Discuss Tungsten absorber
  • Cover 1.5 crystals ok? 1 layer may be sufficient
  • Rohacell supported
• Monitoring System
  • Testing plan?
  • 1mm fibers - Josh has them
  • 15cm square with 6mm 45 degree bevel - 2 pieces made
  • Diamond end mill procured
• Electronics/Cabling
  • Use HV and signal patch panels inside dark room, any details? Top and bottom?
  • HV cables are 48 wire with PCB mounted connector, 33 cables
  • 1600 signal connectors on patch panels
  • Heat load for new bases? May be as high as 1 watt
  • May replace existing Cockroft-Walton bases with higher heat load bases too
  • Need to decide to penetrate dark room or use existing labyrinths (enough space?)

• Design Requirements/Specs
• Crystal Array
  • Crystals, 2.05cm square, 20cm long
  • Design for 40 x 40 array with ability to go 32 x 32
  • 2 x 2 crystal hole with annealed steel insert, 2mm wall, 3.8cm ID
  • Inset crystals 12.5cm DS of Lead glass blocks
  • use 25um brass straps
  • 350 um mu metal
  • additional 50um mu metal inside
  • separate by 25um kapton

• Tungsten Absorber
  • 6 cm thick
  • cover 1.5 crystals?
  • Support on rohacell, align to center tube

• Monitoring
  • 1/2" acrylic sheet
  • 6mm x 45° beveled edge
  • LED/ 1mm fiber input through Rohacell
  • Total number of fibers = ?
  • Gasket between module end and acrylic to reduce cross talk

• Cooling
  • Design for 10°C
  • 2.1 KW needed? Maybe more if new bases are 1W each - 2 chillers?
  • 11 parallel circuits for each chiller
  • 2 manifolds (BL, BR)
  • potted copper tubes into aluminum conduction cooling blocks
  • Cooling of center tube needed and to be removable
  • Entire Dark room is an insulated freezer
  • De-humidification needed
  • Air/water heat exchangers (4x)

• Assembly Media:FCAL Insert Module installation procedure.pdf
  • Measure existing FCAL geometry before removing
  • Measure stacks of crystals before assy
  • 19 lead glass blocks surround crystals on each side
  • Determine qty and location of aluminum shims
  • Machine Rohacell to measured size
  • Pre-assemble acrylic/fibers/Rohacel before installation

Minutes and Action Items

• Need to come up with cabling plan (all)
• Need to revisit cooling (maybe as high as 4.5KW) (Tim/Keith)
• Look at cooling system burp supply/return penetrations (Tim/Keith)
• Need to look at AC power requirements
  • (18) 208V/20A circuits
  • (6) 120V/20A circuits
• Need a plan for storing cables and modules when removed from existing FCAL (all)
• Need workspace for refurbishing existing modules (all)
• Need to come up with labelling plans for modules and cables (Sasha, Fernando)