Bcal Action Item Tracker

From GlueXWiki
Jump to: navigation, search

The following persons connected to a phone conference to review the action items that need to be tracked in preparation for CD-3

Online: Kathryn, George Lolos, Zisis, Andrei, Elton, Elke, George Biallas, Chuck, Tim, Christine, Pavols, George Voulgaris.

The Action Item Tracker will be kept up-to-date and used to list items that need attention, goals for addressing them, and when they are closed out. We went over the list and discussed the time scale for addressing them:

  • Installation [Jlab]
    • The current plan is to assemble the Bcal outside the magnet and then slide it into the magnet.
    • Dec 1: for Hall D engineering to develop this concept. This will include the concept for how to connect one module to the next.
    • Ideas:
      • (George) Use an O-ring groove in the Al plate to seal light.
      • Tongue and groove technique with screws to pull them together / use a strap to pull the entire ring together.
      • (George) Use Teflon pieces to cover the iron "filler" pieces in the magnet for the support. Can use similar type supports on the outside to create a supporting craddle. Slipping the Bcal into place would not require matching two different schemes for the support.
  • Winston cone geometry [Regina]
    • Dec 1: To provide a concept for matching the light guides (LGs) to the trapezoidal area of a Bcal module, and to consider how to make the assembly light-tight. There are no plans for aluminizing the outside of the light guides. Cross talk and precise location of glue joints for LG-to-LG coupling need to be considered.
    • Next week: Mail a sample Winston light guide to Tim for reference (Tim will send precise address to George).
  • Eddy Currents in Bcal (during magnet quench) [Jlab]
    • Need to break the connection around the circumference in at least one place (likely the "keystone" module).
    • Dec 1: This will be developed along with the installation procedure.
  • Attachement of SiPMs to Winston Cone [Regina]
    • Date? Concept by Regina/JLav Engineers. A supporting (honeycomb-type) frame may be needed to keep the SiPMs against the BCAL; spring loaded pressure action is needed, as the LGs will not be glued to the SiPMs.
  • Fiber Specifications [Regina and JLab]
    • Next week: George and Christina will send Elton specifications already written as a basis for the document. (See also one of the Tables in GlueX-doc-866.)
  • Light Guide Design for Outer Layers [Elton]
    • Next Week: Blake will send Elton code for light guide collection.
    • Dec 31: Proposal to include shape and connections to PMTs.
  • Length of Bcal
    • Decision to finalize the length at 390 cm.
  • Bcal Timing [Regina, Athens]
    • Alex has shown that even sigma=400 ps is useful for pi/p identification for momenta ~ 500 MeV/c
      Bcal Tdiffpip thumb.jpg
      and full size picture is visible here.
    • Jan 15: Single channel diagram for electronics including splitting of signals.
    • Jan 15: Determination of least count needed in TDC (F1 TDC options are 64 channels of 60 ps, or 32 channels of 120 ps).
    • Jan 31: Determination of suitability of CFD or LE discrimination.
    • Jan 31: Testing of CFDs using cosmic-ray setup. Note: Alberta CFDs do not use NIM levels and a converter is required. JLab will provide converters for common signal levels once Regina provides the interface details.
  • Increased Sampling Fraction [Regina]
    • Can increase number of p.e. in the shower. However, simulations need to show that increased shower leakage does not negate this effect.
    • Jan 15: Study option of using 3mm Pb Sheets in the front of the calorimeter and 5mm Pb sheets in the back part (precise division to be determined).
    • Christina: Questioned the availability of uniform 3mm Pb sheets. George: These are difficult to obtain in US, but are available from Europe. If the thickness allows for swagging the uniformity is determined by the machine (George/Zisis, please check this statement). Prototypes of different thicknesses were obtained from Pisa; Large images are shown at the following links for 1.0mm Lead Sheet and 0.2mm Lead Sheet, and thumbnails right below:
      1.0mm thumb.jpg 0.2mm thumb.jpg
      notice how the lead does not completely fill the gaps between fibers for the 0.2mm sheets.
    • George: At the same time the physics impact needs to be carefully checked.
  • Impact of energy near threshold and number of p.e. in Bcal [Regina]
    • Jan 15: Will be considered along with the previous item.
  • Temperature stabilization of SiPMs [Jlab]
    • Jan 31: At the collaboration meeting the question was raised as to whether Peltier junctions could (should?) be used to stabilize the temperature (not cool) to about 70 deg.
    • George: Questioned whether cooling of large area (i.e. arrays) had been looked at from a technical point of view. (Cooling Solutions.)
    • Bill Crahan and Fernando will be tasked with addressing the cooling/temp stabilization of the Bcal readout.
  • SiPMs - Statement of Work
    • George has provided a draft. Elton and Elke need to give feedback
  • Calibration system [Athens]
    • Need concept to determine location and impact on spacial constraints.
    • Christina: Would like to keep the options for the laser and photo-diode systems.
    • Christina: The specs for the IU laser were checked and will meet their requirements. They will contact Matt to determine shipping details.
  • Fabrication/QA plan [All]
    • February: Will revisit in Jan.