Minutes 12-6-2006
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FDC Weekly Meeting
Date: December 6, 2006
Participants: Daniel, Brian, Simon, Tim, Chuck, Roger, Fernando, Stan
Next Meeting: Wednesday, December 13, 2006 @ 1:30 p.m.
Contents |
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Mechanical Drawings
We began by reviewing the latest mechanical drawings of the FDC
produced by Tim and Chuck. We currently have the following:
- 5.5 mm wire spacing
- 6 daughter boards (16 channels each) on the wire planes
- 8 daughter boards (24 channels each) on the cathode planes
- Tim and Chuck are still optimizing the anode and cathode
layouts; they will work with groupings of 8 channels
- The cathode pitch may be adjusted slightly from 5 mm to get strip
numbers to match up with preamp channels.
- 3 STBs have 24, 48, 24 wires, respectively.
- DSC has produced a document on the FDC circuit board layout for
the wire plane - request feedback on the layout and component
choices.
Tim and Chuck need to interact with Roger and Kim soon to make progress on the board layout for the wire plane. We need to know how much space is needed for the traces and components, as well as the daughter boards.
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Preamplifier Cooling
Fernando discussed his ideas for cooling the preamps. He proposes
a connection to a ground plane on the back side of the ASIC. This
plane then leads to a connector on the edge of the daughter board.
Tim then suggested that with a small copper wire (~2mm in size), we
could connect to the rods going through the chamber stack to get the
heat out. We could use a flow of dry air in the FDC ``cocoon" to
cool. Using dry air could also help with humidity control. We should
strive to avoid having to use water or other liquid coolants.
- Both Fernando and Tim will continue to think about this. However
it now looks like we can keep the daughter board design relatively
simple with respect to cooling, which should keep costs down.
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Temperature Monitoring
Stan suggested that we include a thermistor on each daughter board. This should be added to the budget estimate.
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Cathode Board Drawings
Roger and Kim provided design drawings for the dummy cathodes and the on-chamber electronics for the wire planes. We need to come up with labels for the title blocks. Roger and Kim will use the JLab naming convention for all FDC-related drawings.
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Daughter Boards
Fernando will work with us to select an appropriate connector for the daughter boards. Roger needs this soon. In looking quickly through a catalog, we did find connectors with the required 5 mm profile.
Fernando argued that the daughter boards should have the ASICs spread out horizontally instead of vertically on both the cathodes and anodes to make the board design easier. Tim and Chuck will modify the mechanical drawings to handle this.
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Cathode Flatness
Brian and Simon have talked to the JLab survey group (contact Chris Curtis) about the cathode flatness measurements. They may be able to modify an existing system they have to perform a non-contact measurement with the required tolerance. They are looking into this and will get back to us. The survey group could also measure the wire separations using optical techniques (slow and tedious) if we needed this.
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Wire Winding
Brian has been in contact with Karen Kephart about the stringing of
the FDC wire planes. We would like FNAL to perform the stringing,
the deadening of the central 7 cm hole, the wire tension measurements,
and the wire spacing measurements as part of this task. We need an
estimate for the budget.
- We further discussed when the boards would be stuffed. It would
be best for us if the boards could be stuffed before winding. Brian
will talk to Karen about this. Roger indicated that this would not
be a problem in the design.
- Karen has asked us to think about pre-tensioning the boards before
winding. We need to think about this.
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FDC Spec. Sheet
We reviewed the spec. sheet that Elton had made for the FDCs. Stan will look this over and provide feedback to us (as well as any questions that he thinks about after considering what we are doing).
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F1 Modifications
DSC reported that he had talked to Chris Cuevas about modifications of the F1 TDCs to include the ability to pulse the ASICs for calibration purposes. This approach is being designed into the FADCs. Chris indicated that this would not be a major deal.
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HV Mainframe
Simon will follow up on the design of the HV system (mainframe,
modules, channels, etc) and get back to Elton. This will close
the loop on this budget item.
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Force Calculations
Fernando stated that we need to perform force calculations for the
wire planes to converge on tensions and forces on the wire plane
board.
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Cathode Mechanical Mockups
Cathode mechanical mockups will be constructed in the EEL shop
area on the flat table. Brian is presently gathering materials
and parts for this task. We will need to keep on top of this
work so that we can make sure that we can meet our mid-January
time line for a design decision.
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FDC Budget
We reviewed the FDC budget that is being prepared. It is due
December 19 to Curtis and Elton. The remaining work areas are:
- Printed circuit boards (STBs, HVTBs): Fernando
- Preamp daughter boards: Fernando
- Ground planes: Brian
- Mounting system: Tim, Chuck
- Chamber cooling: Fernando, Tim
- Chamber stringing: Brian
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Site Visit
We visited Chuck's office after the meeting and he showed us his
mechanical 3D drawings of the FDCs. They are progressing nicely.
We will have much more complete drawings by the time of the FDC
review in Feb/Mar. Note that Brian has suggested a modified keep
out zone for neighboring cathode and anode daughter boards that
Tim and Chuck will incorporate to be sure that we have no space
conflicts.
Minutes prepared by Daniel. Send any comments or corrections along.
