FDC Weekly Meeting
Date: October 23, 2008
Participants: Daniel, Bill, Fernando, Mark I., Mark S., Herun, Eugene, Kim
Next Meeting: November 6, 2008 @ 1:30 p.m.
- No FDC meeting next week due to the Hall B Collaboration meeting. DSC will talk to folks throughout the week to ensure things are progressing.
Full-Scale Prototype Updates
- Procurements: * Roger has not finished the design work for the cathode rigid-flex assemblies. He has agreed to complete this work by the end of Oct. and submit the PR. We also need to work out a plan for stuffing these boards. Before the design work is considered done, Fernando will be responsible for double-checking and blessing it. * Roger completed the order for the Moire interference masks for the Phase 2 wire winding. They have already been received by IUCF. * Roger will contact the Allflex sales representative next week regarding the remainder of our cathode order for the full-scale prototype. The sales rep. was out of the office this week. * Kim has placed the procurement spreadsheet on the mdrive. * Location: M Drive/halld/Electronics, or for more sophisticated folks, /u/group/halld/Electronics. * Folks should fill it out in the given format. * The orders for a spool of the sense and field wire are out the door. Expect delivery in 2 to 3 weeks. * G10 ring order status: * Brian has received information about the G10 thickness tolerance. The manufacturer claims +/- 6 mils, but our measurements show that it is half of this and more like +/-2 mils. Brian will find out if they can get the order to us before 4 to 6 weeks (which seems to be the new delivery schedule that we have received). He will make some calls on Monday. He will order 10% more than is required for the full-scale prototype. Given our planned manufacturing process, the sheet thickness and tolerances are not super critical. * 110IG Rohacell order status: * Bill and Mark have found that over all of our 110IG samples, the thickness variation is +/- 7 mils. However, a given piece or sheet is closer to +/- 2 mils. * Given our planned manufacturing process, the sheet thickness and tolerances are not super critical. * Bill has prepared several possible PRs, depending on what Elke wants to do. We can get a quicker delivery date (by a couple of weeks) if we pay a premium. The decision will be based on how soon the G10 can get here. - Mark S. will take responsibility for watching over the FDC component stores and keeping the database up to date. Kim will provide him with the excel spreadsheets for what we now have. All boxes are sitting in F117. - Bill is working to put the local HV connectors selected by Fernando into the 3D CAD model and to detail how they will be attached (as they are quite massive). Bill will get back to this work when he has a chance.
Wire Frame Construction
- We have settled on a thickness tolerance for the wire frame of 8 mils to match the thickness tolerance for the cathode frames. - I think we have settled on a construction approach that will allow us to meet our thickness specification. We will be milling the completed G10/epoxy/Rohacell laminate to a fixed thickness in the JLab machine shop. The advertised tolerance possible from Casey A. is 3 to 4 mils. This will then be added to the 4 mil uncertainty from the PCB/epoxy layer. - Bill will plan on working with Casey to test the milling technique using laminates made with our HF31 Rohacell stock. - Fernando looked at the PCBs that came back from Greg Arnold's group and was happy with the work. - Herun redid all of the electrical testing on the STBs and all boards checked out O.K.. - Drawings for the PCB have been provided to Bill and he had imported them into the 3D CAD model. - A minor problem has been found with one of the STB boards due to a screw-up at the board house. We should have spotted the problem during QA at our end, but it was missed until just recently. The problem was in the overlap region on one of the STB boards. The problem can be remedied by the machine shop and Bill and Kim have already met with Casey. After the machining to fix the problem, Kim will send the boards over to Greg Arnold's group for cleaning. - Mark S. worked to laminate the solder sample PCBs to the G10/foam layer with unpleasant results. During the vacuum bagging procedure, the epoxy ran out uncontrollably and made a mess. Bill is already devising modifications to the technique. There are lots of cool materials out there for this kind of work. Bill has already ordered some and will lay out some test plans to finalize the procedures on some test pieces.
- The work that Bill is doing to prepare a write-up for the tolerances for the layers for the wire frame will be used to make a similar write-up for the cathodes. More to come. - Brian has been asked to check on the cathode boards in the storage box to make sure that there are no problems. No word yet on if this has been done. - Fernando and Brian will meet shortly with the W&M SEM folks to go over the next steps in understanding the surface deposits on our sample cathode board. - Bill has not done any more work on the system to cut the cathode edges. More to come when he gets back to this. - Cathode flatness measuring system: * Micah is doing some test measurements now. He has defined a grid size of 1 in by 1 mm that allows a cathode scan to be completed in 15 minutes or so. * Micah will do a measurement of the surface flatness of our granite table and then complete the cathode flatness measurements with our high tension cathode prototype. He expects to have results early next week. - Brian has prepared a first draft of a cathode construction document. Bill is working on expanding it with available pictures. DSC passed his comments on to Bill to be added. - Brian was asked to start to move forward on the system to measure the cathode tension in situ and to develop a better system to apply tension. Brian and Bill met after the FDC meeting to go over the existing system to apply tension to the cathodes. The next cathode we make should be set to a tension of 300 N/m. In doing this work, we want to measure the board distortions along and against the strips. These measurements should then allow us to understand how the artwork needs to be scaled (if at all) during the board manufacture of our remaining cathodes. - Herun has done some simulations of the cathode board distortions that we need some more detail on to fully understand what was done and if there is agreement or not with the calculations that Simon and Eugene have done. - We talked about the scale of the cathode board stretching in the direction across the strips and along the strips from the work that Eugene did some time ago. We can expect a fraction of a mm stretching along the strips, but up to (maybe) 2 mm in each direction perpendicular to the strips. This is dependent on properties of polyimide used, final thickness of materials, and tension. Roger may have to do some work to allow for this on this boards or we may have to magnify the art work if the stretching is reproducible. - We discussed a bit more about the glue strip design. Presently we are using Kapton tape with a silicon-based adhesive (a no-no). However, the other known alternative is a Kapton tape with an acrylic adhesive, which is probably too weak. Using our own tape will be very difficult as the glue will have to be kept off the Cu side. More thought on this will be done in the coming week.
Full-Scale Prototype Wire Winding
- The IUCF folks modified the dates in the Phase 2 contract and this was O.K.'d by JLab. Looks like we are days away from a signed contract. - We are going to struggle from our end to get the wire frames to IUCF before the end of the year. 1 week to complete orders, 4-ish weeks for bits and pieces to arrive, 3 weeks to manufacture 4 frames, 2 days for shipping. (Heavy sigh). - IUCF will be sending back our transport box. The paperwork was already sent to IUCF some time ago.
- We are presently focusing on three different choices for the material of the solid spacer. One is polypropylene, one is nylon, and the other is Noryl. Bill will prepare a brief write-up of the pros and cons of each material. Bill has just recently found an epoxy that will bond to polypropylene (made by Loctite). He will order a sample and do some test bonds to check the sheer strength. - We will be working to make a mechanical prototype as soon as the design is finalized.
Stack Assembly Procedures
- DSC, Brian, and Bill will work to finalize the stack assembly construction document that has been prepared. This document should be in place before we get too far in the construction process. - Bill has found some plastic threaded rods that could be used to compress the stack. We will be receiving some samples shortly and will carry out some loading tests.
Cooling System Tests
- Fernando is in the process of writing up the results from his cooling system studies. Stay tuned for the GlueX note. - Bill has done some ANSYS modeling to better study the connector that goes from the daughter board card to the cooling loop. These will be added to Fernando's note.
Gas System Design
- Slava has worked on a preliminary layout of the gas handling system for the CDC and FDC. He provided two options for the FDC system design that were essentially a basic version and a fancier version. Slava's design work was based on the original concept that Brian came up with long ago. We will continue the design work as we have time.
- 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. - Kim has provided a draft of a procedures document for the Phase 1 and Phase 2 wire frame PCB component attachment. She has merged this document with Fernando's cleaning and handling document. The document is being finalized with some additional language on soldering iron temperature vs. time profiles. It should be completed before the start of the Phase 2 component soldering.
- ASIC specification update??? - We still have the lingering issue of the problematic x-y plots from the 2-micron Cu cathodes. Simon will revisit this problem by taking some new pulser calibration data to see if this makes the apparent problem go away.
- The FDC short-term work list has been posted on the FDC web site). 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.