Minutes 2-28-2008
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FDC Weekly Meeting
Date: Feb. 28, 2008
Participants: Daniel, Mark, Simon, Chuck, Roger, Fernando, Bill
Next Meeting: March 6, 2008 @ 1:30 p.m.
Contents
- 1 Test Frame and Prototype Wire Winding
- 2 Full-Scale Prototype
- 3 Composite Cathode Updates
- 4 Grounding Issues
- 5 Gas Volume Definition
- 6 Cathode Board Discussion
- 7 STB/HVTB Issues
- 8 Cooling System Update
- 9 Dry Air Flow
- 10 Small-Scale Prototype
- 11 Cathode Flatness Measurements
- 12 Meeting on LV/HV System Design
- 13 FDC Insertion Planning
- 14 FDC Mini-Review
- 15 Gas System Design
- 16 Upcoming Reviews
- 17 Drawings
- 18 Meeting with ERNI Representative
- 19 Work List
Test Frame and Prototype Wire Winding
- Nothing new to report on the status of the contract for the Phase-1 prototype winding. We will get an update next week on progress.
Full-Scale Prototype
- Procurement is underway for materials and boards for the prototype. So far the order for the preamplifier daughter board card connectors has gone out, the Rohacell foam, and the circuit board components (resistors and capacitors). The PR for the wire frame circuit boards is awaiting Elke's signature before being sent to procurement. Hopefully this will happen very early next week when Elke returns from her travels. The cost for these boards was a factor of two higher than we expected (based on earlier version of the quotes that we received). - Brian reported that the company that was supplying our Rohacell is out of business and we will be getting our material from a new manufacturing outfit that is just starting up. No word on how long a delay we can expect. - We still need to start procurement on the G10 skins, a second construction station, the cathode boards, and the cathode daughter boards. The G10 skins should have a PR put together soon. The cathode flex boards and cathode daughter boards will be ready for procurement within two weeks if all goes according to plan.
Composite Cathode Updates
- As Brian was not at the meeting due to required attendance at another meeting, there is no update on the completion of the first composite cathode sandwich. - Brian still has to prepare a gas inlet and outlet tube and perform a trial insertion to finalize this design. - We need to finalize our plans for vibration calculations and measurements. Chuck will check with his sources to find out if there is an expert on-site who can compute the natural frequency of our cathodes using finite-element models. We also need to devise a measurement to make this determination with one of our prototype cathodes.
Grounding Issues
- We believe that we have completed the majority of the design to distribute ground to our chambers. The ground connections for the wire frame will include a "faston" spade connector soldered to a clear region on the circuit boards. This same type of connector will be included to attach ground to the ground plane, although details need to be finalized and a prototype needs to be made. - To attach ground to the cathode boards, the best solution is to include a 10th daughter board card whose sole purpose is to attach ground to the flex board ground pours. All circuit boards will be connected electrically using a thin layer of conducting epoxy at the butt joints. The 10th daughter board will have a ground connection on the back of the G10 skin from a faston connector. A rigid flex board will feed through a cut-out in the G10 skin and be soldered to the ground pour. Note that the ground pour on the cathodes will not be continuous around the ring to eliminate eddy currents in case of a magnet quench. Note that Chuck needs to provide information on where this 10th card can go. - For the FDC TDR, Fernando will provide a brief writeup on the overall FDC grounding scheme. - Fernando has asked for a sample of our ground plane material (about 1 square meter) for resistivity checks. Simon will follow up on this.
Gas Volume Definition
- Bill has completed his para-solid model of the FDC. He will meet with Dave Meekins on Friday to begin the flow calculations. The main question that we need to address is what holes to include in the cathode board. One hole is, of course, the beam hole, but we also need to consider adding holes in the space between the last strip and the G10 skin. This question should be finalized before we order the cathode boards.
Cathode Board Discussion
- Both Roger and Fernando have been pursuing leads on obtaining cathode flex boards with less than 2 microns of copper. Roger contacted CP films, and they cannot go thinner. Another possible contact is Sumitomo in Japan. They claim on their web site that they can sputter copper down to 1 micron. Roger will follow up on this lead. Fernando has been in contact with 3M in Germany. They claim that they can vacuum deposit gold on Kapton down to 0.2 microns. He has had very little luck finding anyone knowledgeable in the company on this front. Perhaps Elke can help by talking directly with the engineers in their native tongue?? Fernando will follow up on this lead. - Roger will follow up with Brian on the idea of including the through-holes on the flex boards prior to delivery. Would he prefer they be made with an exacto knife later on in the process. Tolerances are very tight on the cathode boards due to the placement of the cathode daughter boards. - Roger needs to prepare a write-up for the QA tests on the cathode boards to be done at the board house. This should be circulated for discussion. He also needs to prepare documentation on the QA/stuffing/cleaning details for the cathodes and cathode daughter boards. - Roger is finishing up on the cathode boards to include the new ground connection scheme. He will then finish up the cathode daughter board layout. He expects that these boards will be ready to order in about 2 weeks (maybe less).
STB/HVTB Issues
- Kim needs to prepare a document of instructions for the wire board stuffing. - Kim needs to prepare a document for QA procedures for the wire boards upon delivery. - No update on the modifications to the aluminum construction jig for wire frame and cathode frame assembly. This needs to be done soon. - A group of us met with Greg Arnold over in accelerator about the work to stuff our prototype circuit boards. We provided detailed descriptions of the system and the work to be done. Greg gave us a tour of their facilities. We were all impressed with their infrastructure and it seems clear that they can handle the stuffing of our boards following industry standard procedures. One issue that will need to be addressed soon is the post-winding stuffing that needs to be done. Does this work have to be done in a clean-room environment? How will the final board cleaning stages be handled with the wires in place?
Cooling System Update
- Denny is working to set up our cooling system test. Bill has provided him with some of the materials and instructions. We need to follow up with Denny to find out if he has everything necessary to proceed. The consensus was that once the composite prototype is completed, setting up for the cooling test should be a higher priority. - Part of the cooling tests will include studies of air-cooling for the CDC. Fernando will contact Curtis to bring him up to speed on the proposed test plan and to get his direct input. - Note that Fernando has the thermistors and readout for these studies. We need to include the thermistors on the preamp daughter card voltage regulator, the copper bracket on the card, the mating bracket to the cooling line, and possibly the cooling line itself so that we can map out a complete temperature profile and gradient. These measurements will allow us to finalize the system design.
Dry Air Flow
- Part of the nominal environment control plan for the FDC is a dry air flow system. Chuck will begin thinking about this and provide a block diagram for the system. It could be that we can tap into the air cooling system for the CDC and provide some ducts that feed into the solenoid. The gas flow should be low to avoid introducing and pressure waves
Small-Scale Prototype
- Brian has mounted the first 75 deg cathode (no connector yet). The second one will follow shortly. As soon as they are ready, Simon will move to immediately install them into the small-scale prototype and test them out. Remember, these are the first cathodes that we have with 2-micron copper traces (all others are 5 microns). Simon should prepare a test plan and circulate (especially seeking feedback from Fernando and Gerard on steps needed to bless these boards). Keep in mind that we are still actively looking to go down to 1 micron (or thinner) copper if we can get away with it!
Cathode Flatness Measurements
- Bill has been continuing to track down leads. He talked to the folks at Brown and Sharpe about a non-contact measurement system for their coordinate measurement machine (like the one in the JLab machine shop). They turned him on to an outfit in Charlotte that has a system presently capable of performing these measurements. Bill will get a price quote and see when we could bring a cathode down to them for measurement. Bill will also continue to follow up on putting together a measurement system here at JLab.
Meeting on LV/HV System Design
- We are progressing on the design for the chamber LV and HV systems. Fernando is updating his system design documents and will circulate them when they are ready.
FDC Insertion Planning
- A meeting on FDC (and other system) cabling is being scheduled (tentatively next Wed. at 1:00 p.m.). We need to converge on FDC insertion plans, cable layouts, and cable routing. There are a number of important issues that need to be addressed, such as the ability to pull the FDC out the downstream end of the solenoid, the coupling of the FDC to the CDC, and the cabling system and support that runs from the FDC out the upstream end of the magnet.
FDC Mini-Review
- An official version of the close-out report is not yet available. It will be circulated once it is finalized.
Gas System Design
- Brian (or someone like him) will need to advance the design of the chamber gas handling system beyond the preliminary system design that he prepared quite some time ago.
Upcoming Reviews
- The combined tracking/PID review for Hall D is scheduled to take place on March 27 and 28. At this point, we are converging on a charge and the list of speakers. We have to prepare talks and backup materials for the FDC, CDC, and charged particle PID systems. The details will be worked out over the next week or so and preparations will continue from now until the review. - 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 will circulate the modified FDC TDR and solicit new/updated system drawings to replace outdated ones that he has.
Drawings
- 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.
Meeting with ERNI Representative
- After the FDC meeting a number of us met with Susan Price, a sales rep for ERNI. They will be able to make our signal cables to our specifications, including handling of the 3M connectors, and shielding modifications. She will prepare a price quote for us. - We also discussed details of the mini-bridge connectors for power and the daughter board connectors. She will investigate the issues with long lead times and get back with us.
Work List
- 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.