Monitoring R&D

1. Winston cone (Wicos) versus truncated, trapezoidal (Traps) lightguides (LGs).
   1. Mechanically, the Traps offer advantages: more space to install LED system, flat versus curved surface, square exit to match SiPM window.
   2. Determine the relative difference in collection efficiency with optical grease coupling and air gap.
   3. Test on baby bcal using LED light, cosmics, and possibly also with a fibre bundle.
   4. Finalize LG manufacturing site.
   5. Assignment of tasks to groups/individuals.
   6. Timetable to meet January procurement deadline.
2. FCAL block plus Plexiglas tests.
   1. Complete scans. Ascertain system uniformity across FCAL face, and determine the light amplitude required.
   2. Other issues?
3. Review LED monitoring system: see George V's May 2010 presentation as a reference.
   1. Mounting:
      1. Options: a) LED directly on LG, board behind SiPM electronics. b) LED plus board on LG. c) LED plus board far away, light is brought to LG via fibre.
   2. Improvements to current design are easily done.
      1. LED board: a) Reduce size to 603 format (18x6 mm²). b) Introduce ribbon cable.
      2. LPCM board: a) change USB interface to serial to interface with JLab slow controls. Requires reprogramming of microcontroller. b) Introduce 100-pin connector for easy detatchment of LED cables (32 can be accommodate on each LPCM board). Note that thet LPCM sends a TTL pulse, 4-4.5V and 15ns risetime.
   3. Issues to be address by Calorimetry Group.
      1. LED+LPCM or laser system?
      2. Type of LED?
      3. Channel count: Does every channel of the BCAL (and TOF) need a LED?
      4. Geometry:
         • Final LED board size?
         • Location? Board directly on LG (works for trap design)? Glue LED to LG (probably Wico design needs this)? Use a fibre to transport the light (temp concern for stability of LEDs, and perhaps noise towards SiPM). Where to threat cable from LPCM to LED? Where to put LPCM (piggy back on SiPM board -- RF issue, or in separate box near BCAL, or in electronic racks -- long cables, cost issue)?
      5. Mass production in robotics facility (like IU's)?
      6. Slow controls interface and software. Feedback system to adjust LED bias (include temperature sensor from SiPM?) What is needed for all this?
      7. Dynamic range of SiPMs; can we flash both sides simultaneously, or do we adjust LED biases for near vs far PMT.
   4. How to proceed/Pricing
      1. Athens will write a construction MOU, which will include R&D and a prototyping plan.
      2. Once LED configuration and numbers are settled, an updated quotation will be requested. For example, to instrument all BCAL LEDs, 130 LPCMs are needed each with 32 LEDs, for a total of 3840 LEDs.