FDC Weekly Meeting
Date: March 20, 2008
Participants: Daniel, Simon, Bill, Fernando, Roger, Mark
Next Meeting: March 28, 2008 @ 9:30 a.m. (tentative)
- 1 Full-Scale Prototype
- 2 Test Frame Wire Winding
- 3 Wire Deadening Studies
- 4 Stack Assembly Procedures
- 5 Composite Cathode Updates
- 6 Grounding Issues
- 7 Gas Volume Definition
- 8 STB/HVTB Discussion
- 9 Cathode Board Discussion
- 10 Small-Scale Prototype
- 11 Cathode Flatness Measurements
- 12 Upcoming Reviews
- 13 Drawings
- 14 Work List
- Cathode daughter board design is essentially done. Roger will prepare the PR in the next day or so. He has already received several quotes for these board. The order will be for 5 boards. - Cathode ground board design drawings nearly done. Roger still has to get a blessing from Chuck on the placement of this new board. Once this is done, PR will be prepared. Roger will order 5 boards. - Once Roger gets word from Chuck on the placement of the cathode ground board, he will be able to quickly finish the cathode board design drawings. He is essentially ready to prepare the PR. For the full-scale prototype, we will not worry about holes in the cathodes. They will not come with holes in them, and we will have to make the cut outs ourselves (perhaps using the laser cutting procedure that Bill has presented earlier). - The delivery of the wire frame circuit boards should arrive this week. As Kim is away on vacation, Roger is in charge of looking out for the order, inspecting the boards upon arrival, and passing the boards on to Greg Arnold for stuffing. Kim has already prepared instructions and the components to be stuffed and Roger will give these to Greg. The current plan is that the QA/stuffing/cleaning procedures document will be prepared during/after the stuffing procedure after all lessons are learned. - Some known delivery time lines: Wire frame boards by March 27, 50-pin connectors for wire frames this week, 50-pin connectors for preamp daughter boards by July, ERNI connectors by the end of May, HV capacitors by May 9. - Update on cathodes: > We found out during the week that Sheldahl will not be able to provide our cathode board material for the foreseeable future (1-mil Kapton with 2 microns Cu). They did, however, indicate that we might be able to get 2-mil Kapton with 0.5 microns Cu. Roger is in contact with Sheldahl this week on final word on what they can provide. Simon indicated that the 1-mil Kapton + 2 microns Cu is similar in thickness to 2-mil Kapton + 0.5 micron Cu (basically a wash in terms of radiation lengths). > Roger has been in contact with CCT Marketing (the board house). They are about to shut down. However, they told Roger that if we can get them the board material by Apr. 14, they will be able to get our order in. > We decided to push ahead and order the board material and move on with the order. Fernando indicated that he is not worried about the cathode board performance going to thinner Cu, he is more concerned about soldering/attaching the connectors. We will need to come up with a final procedure for this operation, and presumably we can finalize this procedure on the boards for the full-scale prototype. > We also decided to try to order cathode boards of the 2-mil Kapton + 0.5 micron Cu for our small-scale prototype for checkout. It was felt that we could test these boards electrically much faster this way. The question is whether CCT can handle this order, but we will try. > Roger is now starting the dialog with Sheldahl and CCT Marketing regarding handling and flatness specifications based on the document that DSC prepared. Word to come soon on what can be achieved. It was felt that even if the boards are not any better in quality that the boards that we have for the small-scale prototype, we would still move ahead with the order. > As Brian was not at the meeting, we have not heard whether he has received word from Jack Segal on our move-in date from the EEL building clean room. DSC has requested the information from Brian and we will know soon. - No progress has occurred on modifying the aluminum construction jig due to other commitments.
Test Frame Wire Winding
- As the Phase 1 wire winding contract has been signed, IUCF is now working on getting ready for the test winds. They have indicated that the wire winding machine is fully functional and ready. They are working on setting up the tension measurement system and the wire measurement system. They would like to have everything working at some level before Brian heads out there. - For the wire winding, tension measurements, and position measurements, IUCF is working on developing (and then constructing) jigs to support the frame flat. DSC is working to get IUCF the information that they need (drawing packages) so that they can move forward. - After the meeting, DSC asked the IUCF folks if they would prefer that we send them a wire frame and a strongback. They indicated that this would be very helpful. Brian is working now to set up the shipment to get it there as soon as possible. - It is still not fully clear when they will want Brian to arrive. Hopefully we can converge soon on getting IUCF the information they need. Their manpower is now available for this work and we must work to get them what they need to proceed. - IUCF has received the epoxy sample that we sent them. - DSC is working with Steve Christo to prepare a wire specification document for the tungsten and CuBe wires leading up to procurement. Steve is preparing a document for the Hall B chambers and we will most likely adopt this document for Hall D.
Wire Deadening Studies
- Brian worked with Tom Elliott to complete a test of electroplating on one of our old small-scale prototype wire planes. They prepared a weak copper sulfate solution in an 8-cm diameter dish and submerged the wires into the solution. They had already connected some externals lines to the traces on the PC board and completed the circuit by submerging a Cu disk in the copper sulfate solution. Anyway, they came up with appropriate voltage settings and plating times and came up with a very good first attempt. The finished plating region was reasonably well defined (Brian still will look under a microscope at the edges), but there were a number of hard Cu whiskers that were formed. Tom has a procedure in place already to eliminate these. The process is to periodically reverse the voltage on the circuit. In one setting the copper in the solution plates on the wire and in the other setting the wire is electropolished. A photo is included in the FDC TDR under the wire stringing section.
Stack Assembly Procedures
- Tim and Bill have worked to consider our stack assembly procedures in more detail based on practical considerations. They have prepared a document that we discussed briefly. There were some apparent inaccuracies in the procedures and we will work to finalize this document.
Composite Cathode Updates
- No progress on completing the composite cathode cathode sandwich as Brian had other things to work on this week. This prototype will be worked on to finalize the Rohacell sealing procedure, the ground plane attachment procedure (including connections to the outside), and attachment of the gas ports.
- Fernando will supply an overall grounding specification document very soon. He is working on it.
Gas Volume Definition
- Bill reported that Dave Meekins has been having problems getting the flow calculations done due to the specifics of our large size but narrow gas volumes. Bill is working with Dave to make gas volumes of varying geometries in an attempt to get around the problems encountered. As preliminary answers come out of the calculations, we will go over them and discuss them so that we can make a design decision as to where to put the holes in the cathode boards.
- Kim needs to provide the appropriate CAD files to Bill/Chuck of her board design drawings for inclusion in the model. - Kim has passed onto Brian the details for the needed modifications to the aluminum tooling plate jig for wire frame construction. This work is needed for the jig plate to clear the pre-stuffed components on the circuit boards. The work will be completed within the next several weeks.
Cathode Board Discussion
- Roger needs to prepare a document for QA/stuffing/cleaning for the cathode boards and a similar document for the cathode daughter boards and ground boards. - Roger was planning to do some test soldering for the rigid flex cables to a sample cathode board. No update was given during the meeting.
- Bill Gunning has completed the soldering of the connectors to the new small-scale prototype cathode boards (+/-75 deg, 2 micron Cu) and Simon has gotten them. Simon will clean the boards and then install them into the prototype. The hope is get a cosmic run started over the weekend. Hopefully early next week we will have some results regarding basic electrical properties, signal to noise levels, and resolution. We would like to be able to have something to say regarding the 2 micron Cu performance for the review next week. In order to make this work and get results that are comparable to earlier results, Simon will reinstall the SIP amplifiers and the charge integrating ADCs. - At the current time, Simon is making progress on getting the acquisition up and running again and he is quite close.
Cathode Flatness Measurements
- We decided to push ahead on the cathode flatness measurement. We are working on the followings: > Brian will prepare two samples of a cathode board mounted on a frame to send to the Brown and Sharp folks as well as to the company with the measurement system. There are concerns (raised by the Brown and Sharp folks) that the laser triangulation system might not work on our boards due to high surface reflectivity. It is not clear if we send them samples whether they will look at them. Bill will continue to act as the interface on these fronts. > We will most likely push ahead an order the $1.4k system for use on the horizontal milling machine and CMM here at JLab.
- The combined tracking/PID review for Hall D is scheduled to take place on March 27 and 28. We are presently working on the TDR and the talks. Complete details are given on the Hall D web site (http://www.jlab.org/Hall-D/guest_secure). - In preparation for the meeting, we will need an updated set of design drawings for the FDC web site. New drawings from the mechanical model will need to be provided that reflect the current design.
- DSC has collected all of the available FDC subsystem design drawings and placed them on the FDC website. The URL is: http://www.jlab.org/Hall-D/detector/fdc/drawings.html. Folks should go through the drawings and let DSC know what drawings and/or categories are missing for a complete design set. - Also folks should send DSC the latest design drawings where there have been changes to keep this web site up-to-date through the review season.
- The FDC short-term work list has been posted on the FDC web site (see http://www.jlab.org/Hall-D/detector/fdc/). This is continually being updated and DSC welcomes any feedback or comments from the group.
Minutes prepared by Daniel. Send any comments or corrections along.