Minutes 2-7-2007
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FDC Weekly Meeting
Date: February 7, 2007
Participants: Daniel, Tim, Roger, Fernando, Kim, Simon, Brian, Elke, Chuck
Next Meeting: Wednesday, February 14, 2007 @ 1:30 p.m.
Contents
Design Issues
- At last week's meeting we discussed a current issue with the design regarding the space available for the daughter board and connector on the cathode plane face that is closest to the anode board. Presently there is no straightforward way to fit these connectors in without trimming down the g10 spacer or adding clearance notches to the anode board. None of these solutions is ideal and all of the solutions suggested so far would lead to a weakening of the boards which would increase flexing and bowing. - Fernando will look into trying to find thinner connectors for the daughter boards. We need to find connectors thinner than about 5.2mm to avoid having to cut into the back of the wire plane g10 frame. Fernando thinks that this is possible and will look into it. He stated that he is very much against having to machine the connectors thinner. He believes that this would destroy their integrity. - It became clear as the discussions continued that we will have some problems with clearance no matter the thickness of the daughter board connectors. DSC suggested a separate concentrated meeting on this issue with a subset of the FDC team. - As stresses on the g10 frames are a possible issue, Tim will look into carbon fiber.
Design Rules
- DSC has prepared a list of PC board design rules that has now been looked over by Fernando. After the meeting DSC sent these off to Kim and Roger so that they will have some general guidance on how to produce the STB and HVTB boards for the FDC.
Cable Layout
- Due to access issues with the daughter boards, we decided to keep the signal cables located from rail to rail. In the space under the rails, we will pack the HV, LV, gas, coolant lines. This will lead to roughly uniform material thickness around the system. - Chuck has prepared a new drawing showing a single FDC package and the cable locations. - We could not discuss this more without Joe B. being present. We will come back to this at our next meeting.
Daughter Board Design
- We revisited the daughter board design. Fernando suggested that we consider as nominal a 50-pin connector for the cathodes (this will give compatibility with the FADC) and 34-pin connector for the anodes (to give compatibility with the TDC). Before we worry too much about these details, we need to make a final decision on the readout. If we can achieve sufficient timing resolution with the FADC with a simple, CPU-acceptable algorithm, we may still decide to use the FADC on the anodes. - For now Fernando has designed the board with 3 ASICs. We will worry about the 2 ASIC daughter board later.
Engineering Work
- Tim has done a number of calculations of stress and thermal environment. DSC will schedule a separate meeting with him to go over this work.
Ground Plane Thickness
- Brian provided Gerard Visser with a sample of our ground plane material (6.3 micron Al-mylar). Gerard will let us know if this material is appropriate for our use in the FDC.
Cooling System
- DSC asked Tim to start a design for a liquid-coolant system for the FDC electronics. Tim will begin a layout and will work with Fernando to get new thermal simulations completed to optimize the design. - Tim suggested a water-cooled system as these units can be bought off-the-shelf without any real design work required.
Cathode Mechanical Mockups
- The first full-scale cathode sandwich has been completed using bare kapton for the cathode boards. This has been delivered to the JLab Survey group for measurements of flatness. These measurements should be completed by Friday. - DSC asked Brian to prepare another cathode board using the tensioning system as an alternative to the Rohacell backed version. At issue is the multiple scattering contribution due to the Rohacell. Brian will begin work on this shortly.
Preparations for DC review
- The drift chamber review that will include the CDC and FDC has been scheduled for March 6. In preparation for this review, we need to prepare a technical design document for the FDC. DSC and Simon will prepare an outline and then folks will be asked to provide writeups to be included in this document. This includes Brian: Gas, cathode sandwiches; Fernando: thermal simulations, daughter boards, Tim: Cooling system, stress calculations; Simon: prototype studies, shaper studies; DSC: FDC design, MC. Emails for requests of specific sections will go out shortly.
Minutes prepared by Daniel. Send any comments or corrections along.