Jan 15, 2013 Calorimetry

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Teleconference Time: 11:00 a.m. EST

  • ESNET (Number is 8542553) and EVO session (GlueX Calorimetry meeting room)
  • Phone connection only upon request.
    • +1-866-740-1260 : US+Canada
    • +1-303-248-0285 : International
    • then enter participant code: 3421244# (remember the "#").
    • or www.readytalk.com (and code without the #)

Participant Direct Lines

  • JLab Phone: in CC F326 is 757-269-6460 (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

Items for followup from previous meeting(s)

  1. Produce plots of SiPM parameters, such as the ones already shown, for Vover=1.0, 1.1 V (Orlando) Plots showed last week at the Bcal Readout meeting.
  2. After summary of SiPM parameters, provide data to Hamamatsu for comments (USM)
  3. Monitoring
    • Suggest a range of signals in mV required for the LED monitoring system (IU)
    • Investigate alternative LEDs and or sanding options to increase light output for green LEDs (Athens)

Tentative Agenda

  1. Announcements
  2. Review of Action Items
  3. Monitoring
  4. FCAL
  5. BCAL
  6. USM
  7. Simulations
  8. TDR update
  9. Calibration of Calorimeters
  10. Any other business


Attendees:Elton, John L., David, Yi, Eugene, Lubomir, Beni (JLab); Hayk, Will, Orlando, Alam (USM): Shaun, Andrei (UofR); Christiana, Pavlos, Stratos (Athens); Matt, Kei (IU).

  1. Announcements
  2. Review of Action Items
  3. Monitoring
    1. Media:FCAL-Monitoring.pdf. See also e-mail from George
    2. Media:Reflectance test 1.pdf
    3. Media:Light Intensity blue 130x130.pdf
    4. Christina: Two main efforts under way:
      1. Determine if LED with longer wavelength than blue will give sufficient light
        • New green LED x5 times more intensity than previous. However, the pulses are wider, so this translates into a pulse height increase of 2-3. Testing is being done with mesh pmt, not the Fcal module due to difficulties of making the enclosure light tight.
        • Original blue LEDs gave 180 mV signal at 20 V bias, original green LEDs gave 23 mV at 28 V bias. (New green would be expected to give 2-3x, or 50-80 mV but needs to be confirmed).
        • Eugene: Inquired if white LEDs might provide more intensity and whether they should be considered.
      2. Understand non-uniformity of light delivery and test options for minimizing the range of distribution.
        • Hot spots are at the edges, thought to be due to reflections off the edges.
        • The hot spots are within 2 cm of the edge.
        • Repeated measurements with black paper placed on edge (near adjacent quadrant in experiment). This shows an improvement in the uniformity of light collection, but still has a hot spot.
    5. The normalization of the signal is not understood. We need to take some data with the full Fcal module and a specific pmt gain (i.e. voltage) so that one can establish the range of signals from the monitoring system relative to particle interactions. Also, IU needs to determine the expected range of voltages (i.e. gains) of pmts for the experiment. Eugene: Cosmic rays could also be used to establish a rough normalization.
    6. BCAL boards
      • Bcal boards are packed and ready to be shipped out tomorrow
  4. FCAL
    1. Stacking
      • John Frye arrived yesterday with auxiliary equipment from Indiana
      • The truck was unpacked by noon and setup began. The workspace has been organized.
      • Dan and John L. have been assembling modules (15 completed)
      • Survey and alignment made some adjustments after the frame was placed back on the forward carriage (it was stored on the floor over the break)
      • John F. has been aligning the steps getting ready for stacking.
      • Elton: Inquired about the mylar sheet inserted between the mu-metal and the iron. John L: Cutting is cumbersome now but insertion is easy. A role of correct width has been ordered and will be arrive soon, so the process will be streamlined.
      • Eugene: Need a gap between the mu-metal and iron to make the shield effective for transverse fields. The 50micron mylar is relatively small for this. On the other hand, it does insulate the mu-metal from the iron and lets if float.
    2. PMT Tests (Kei)
      • Reviewed procedure for selecting tubes to be used in the detector. They have identified sufficient number of good tubes, which will be used in the initial stacking. A few percent of tubes will be rejected, the remainder will be used as spares.
      • Andrei: Expressed opinion that not only PMT gain but also the rise of PMT noise at high operating voltage might affect V0. Proposed to check the agreement between obtained V0 and PMT gain (from a direct gain measurement) for 10-20 PMTs. It was felt (by Matt, Elton etc.) this was not necessary, as this procedure will only be used as a starting point for calibration with particles.
    3. FCAL Beam Test (Kei)
      • Due to lack of time, this presentation was delayed to the next meeting.
  5. BCAL (Elton)
    • We are starting to setup the gluing station for light guides this week. Elton is working with Tina, who has been reassigned from the FDC effort. So far we have been preparing the setup and hope to have a dry test tomorrow.
    • We have 20 strings of LEDs (sufficient for over two modules)
    • We have more than half of the light guides in hand
    • The templates for the light guide covers will stamped out on Wednesday. We are preparing sufficient covers for the first module by hand.
  6. USM
    • Orlando posted a histogram of capacitances for 3 temperatures following the Bcal readout meeting. The plot is for the pixel capacitance; the capacitance of the array is 3600x16 times larger.
    • An improved procedure for packing light guides has been implemented. The next shipment of light guides (expected tomorrow) will use the new system.
    • The SiPM custom issue is expected to be resolved within the next few days.
  7. Simulations
    • "Status of Sampling Fraction Study" (Andrei)
      • Due to lack of time, this presentation will be delayed till the bcal readout meeting next week.
  8. TDR update
  9. Calibration of Calorimeters
  10. Any other business