May 3, 2011 Readout

Teleconference Time: 11:00 a.m. EST

• ESNET 8542553 and EVO session
• JLab Phone: in CC F326 is 757-269-6337 (usual room)
• JLab Phone in CC L207 is 757-269-7084
• Phone in the Regina Videoconference Suite is 306-585-4204
• Athens Phone: in Christina's office is 011-30-210-727-6947
• Phone:
  • +1-866-740-1260 : US and Canada
  • +1-303-248-0285 : International
  • then use participant code: 3421244# (the # is needed when using the phone)
  • OR from www.readytalk.com type access code 3421244 into "join a meeting" without the # (you need java plugin)

Items for followup from previous meeting

1. Check if connections for cooling fluid can be bent radially outward to minimize affect on photons in the gap. Yes. Simulations of impact needed.
2. Need to get a firm number for the power dissipation in the monitoring control board (in case it is placed inside the housing box)
3. SiPM: check cross talk between cells (Yi and Carl)

Tentative Agenda

1. Announcements
2. Review of Action Items
3. USM update More Pictures
4. SiPM update
   • Regina Preliminary Tests of Hamamatsu prototype
5. Electrical/cooling (Elton)
6. Geometry and light guides
   1. New Geometry
   2. Current geometry of light guide in Monte Carlo
7. Simulations

Minutes

Attending:Beni, Yi, John, Tim, Elton, Eugene (JLab); Will (USM); Andrei (UofR); Christina (Athens)

1. Announcements
   • SiPM First Article arrays have been approved
   • Jlab 6 month shutdown begins in 2 weeks. They plan to connect the accelerator north stub with the tunnel to the tagger hall during this period.
2. Review of Action Items
3. Monitoring (Christina)
   • MOU signatures should be completed soon
   • Started this week to measure the light distribution in a 1x1x0.15 m3 plexiglass pane to be used to determine how many LEDs will be needed for the Fcal monitoring system.
   • Hope to have some results to present next week at the collaboration meeting.
   • Asked about light guides from USM. The guides are cut but not polished. Need the guides to check the space for boards and cables.
4. USM update More Pictures
   1. Will described the considerable progress at USM on several fronts. Check the presentations for photos.
      • (Finally) received SIPM array out of customs (no cost, but time consuming)
      • Took some photos of the SiPMs under a microscope, which showed some small specs on the surface. Visually, these specs appeared to cover sub-percent fractions of the surface, there is no quantitative evaluation yet. They also did not check if they could blow these off. The specs were not visible by eye.
      • Further studies will proceed.
   2. Checked cooldown
      • Cooldown time is about one hour (electronics not connected in this test)
      • Dark box with cooling system has been placed in a dedicated room for this measurements.
   3. Electronic boards received
      • Boards are populated and will start to get connected
      • Eugene: Check that the connections have capacitance smaller than the array cell itself (~320 pf/16). The main effect of this will be timing.
   4. Light guide production
      • Light guides have been produced (cut by CNC machine) but are not yet polished.
      • Broken part on CNC machine was broken but is now repaired.
      • Tim: Jlab can practice gluing with these guides when they arrive.
5. SiPM update
   • Regina Preliminary Tests of Hamamatsu prototype
   • Links left from last meeting showing some oscilloscope measurements of uniformity between cells in a SiPM array.
6. Electrical/cooling (Elton)
   • Progress on several fronts:
   • Mechanical cooling prototype parts have been ordered and expect to arrive at the end of the month
   • Electronic boards have been designed and laid out
   • Prototype of a complete sum unit is underway. It includes a cooling block with Peltier cooler, cooling plate, temperature compensation electronics, amplifiers and summed circuit.
7. Geometry and light guides
   1. New Geometry
      • Elton presented a new variation on phi-symmetric guide geometry. The new geometry has only 10 different light guide shapes.
      • There is a small gap on the inner side with the present layout, which may need to covered by stretching the layout a slight amount.
      • There are advantages in simplicity and symmetry for the new geometry.
      • No objections, but many advantages are seen for the new geometry, so the decision was taken to move to the new geometry for production units. [Note that all ongoing prototyping efforts will proceed with the old geometry.]
   2. Current geometry of light guide in Monte Carlo
      • Beni investigated the MC geometry of the light guides and finds that there is a mistake in the geometry for the outer light guides. These overlap with other volumes and must be fixed.
      • Beni will implement the new geometry and fix the MC at the same time. Note that the MC geometry has always been phi-symmetric.
      • The incorrect geometry has no direct effect on the present studies of granularity. The light guides (and incorrect geometry) primarily effect efficiency and background studies in this area.
8. Simulations
   • Andrei emphasized that we do not understand the Bcal reconstruction software and ongoing studies cannot be interpreted reliably without well-defined inputs and reconstruction parameters.
   • Suggested to document what is known about the program and evaluate what needs to be done to achieve a robust photon reconstruction.