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.
1). 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.
2). Preamp 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.
3). Thermistor Readout:
Stan suggested that we include a thermistor on each daughter board. This should be added to the budget estimate.
4). Design 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.
5). Daughter Board Connectors:
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.
6). JLab Survey Group:
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.
7). Wire Stringing:
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.
8). Designer Interactions:
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.
9). Daughter Board Layout:
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.
10). 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).
11). F1 TDC 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.
12). HV System Design:
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.
13). 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.
14). 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.
15). 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
16). Visit to Chuck's Office:
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.