Mar 3, 2011 Calorimetry

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Teleconference Time: 10:30 a.m. EST

  • ESNET (Number is 8542553) and EVO session (GlueX Calorimetry meeting room)
  • JLab Phone: in CC F326 is 757-269-6337
  • Regina Phone: in LB228 is 306-585-4204
  • Athens Phone: in Christina's office is 011-30-210-727-6947
  • Phone connection only upon request.
    • +1-866-740-1260 : US+Canada
    • +1-303-248-0285 : International
    • then enter participant code: 3421244# (remember the "#").
    • or (and code without the #)

Items for followup from previous meeting(s)

  1. Monitoring
    • Zisis will gather Andrei's tests and overall ideas for BCAL monitoring system.
    • Fcal: check cross talk of calibration inputs across modules.
    • Develop drawings of Fcal with the plexiglass sheet as a reference to develop further details.
  2. Fcal construction
    • Mechanical: Tim has promised review of support structure. Wayne Sachleben has started the review
    • JLab to provide shipping guidelines to Matt

Tentative Agenda

  1. Announcements
  2. Review of Action Items
  3. Calibration
  4. BCAL
    1. Construction Status: builds, fibre QA
  5. Simulations
    1. Readout segmentation (Andrei)
  6. FCAL
    1. Construction Status: mechanical, bases IU FCAL struct dwgs
    2. Drawings for Fcal structure (Tim)Sketches for comments on FCAL structure


Attending: Matt, Ryan, John (IU); Zisis, Andrei (UofR); Elton, John, Beni, Tim, Yi, Wayne Sachleben, Dave, Eugene, Lubomir (JLab)

  1. Announcements
    • The director had an all-hands meeting yesterday to update the lab on the fallout of a possible government shutdown if budget issues are not resolved. The lab has about one month of operations funding and it will take about that long to react to a shutdown. The director did not have any more information than what is in the papers, but wanted to outline the situation and possible options when congress takes action.
  2. Review of Action Items
  3. Calibration
    • No report. [Note: Christina joined, but had communication issues].
  4. BCAL
    1. Construction Status: builds, fibre QA
      • Matrix fabrication going well. No. 31 and 32 should be completed next week. That will give a total of eight ready to be machined.
      • They have given Ross machining three extra weeks to complete a large job from Alabama. Machining the Bcal modules in the middle of the other larger job had certain risks that we wish to avoid. After the Alabama job is completed, eight modules in a row will be machined and shipped to Jlab by mid April.
  5. Simulations
    1. Readout segmentation (Andrei)
      • No new results, but progress is steady. Expect a report at the next working group meeting (in two weeks).
  6. FCAL
    1. General mechanical
      • Finishing wrapping glass. All "best" modules have been wrapped. Starting to use blocks with minor blemishes, which will be sufficient to complete the job.
    2. Cockcroft-Walton bases
      • 450 out of 500 bases have been received. Minor failures have been fixed, but 15 remain with mysterious failures. Paul is investigating.
      • 300 good tubes are hooked up to the CAN network, which was dropping out after a period.
      • Dan Bennett found that a transmission error counter is incrementing and the bus hangs up after a certain number of errors are counted. The source of errors have not yet been identified, but setting a bit to reset the counter during idle times can be used and allows the system to run for long periods.
      • Beni: Asked about the communication speed. About 100 channels can be hooked up to a single controller and it takes about 3-5 min to address and set all of them. The software is currently set at its lowest speed and addressing each channel individually, while the protocol allows a broadcast option. There should be other ways of improving speed, but for typical monitoring, this speed might be sufficient.
      • Will start working with Hovanes and Elliott to incorporate this protocol into the online system.
    3. Monitoring
      • Drawings with concept have been shipped to Athens, with some feedback
      • Tim: The space frame should allow the addition of features to support the plexiglass pane where needed
      • Matt: Should consider options for removing the pane and allow for in-situ UV curing of glass. A solution would be to have a light-weight frame for the pane that allows removal.
    4. Fcal Frame feedback
      • Construction Status: mechanical, bases IU FCAL struct dwgs
      • Drawings for Fcal structure (Tim)Sketches for comments on FCAL structure
      • Considerable discussion as this is the first time in many years that this concept has been looked at.
      • Tim: goals for structure are a) safely hold all glass b) be strong enough to move the entire glass assembly a short distance (within the hall) without restacking c) withstand 10% lateral loads (Va earthquake condition)
      • Lubomir: Suggested to add padding (thin rubber) to the sides of frame
      • Blocks are wrapped in <0.001" Al mylar. The straps are 0.003" stainless
      • Wrapping has a 3/8-1/2" overlap which is bonded with Elmer's glue sticks
      • The height tolerance of the frame relative to the glass must be very good, otherwise a gaps will appear. One option would be to undersize the pushing elements and shim.
      • Lubomir: Asks if instead of alternating horizontal and vertical straps, one should put all the straps along one direction? No clear answer, except for symmetry.
      • Discussion of how to stake the top half. Beni: suggestion to leave out the top left half with the right side fixed and build up along with block stacking
      • Wayne: Has calculated large deflections of structure if it was picked up to move (~0.5"). This needs to be of the order of 0.5 mm. This will require a much beefier bottom beam
      • Matt; Check how stability front/back is ensured in the design. Answer could be coupled with dark room?
    5. John, Tim and Wayne will meet shortly (likely tomorrow) and go over more details and current feedback. After considering options, will report back to the working group.