FDC Weekly Meeting
Date: October 16, 2008
Participants: Daniel, Simon, Brian, Bill, Fernando, Mark I., Beni, Herun, Micah, Eugene, Mark S.
Next Meeting: October 23, 2008 @ 1:30 p.m.
Full-Scale Prototype Updates
- Procurements: * Roger has not finished the design work for the cathode rigid-flex assemblies. We should aim 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. * Kim has placed the FDC full-scale prototype 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. * FDC wire order. Brian indicated that Little Falls will meet our specifications for the CuBe wire and that CFW will meet our specs (except for the temper requirement) for our W wire. However, DSC does not have a temper spec for the W wire. He talked to Steve Christo after the meeting and he said that no temper spec is required for the tungsten. This point should be clarified. * 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. * We need to make a decision on whether we will work with the supplier to preselect sheets or whether we will over order, building in a waste factor. We still need to finalize how many sheets will be needed for the full-scale prototype. These decisions are converging and we would like to be able to complete the PR in about 1 week. * The G10 order should include all pieces necessary for all wire frames, cathode frames, gas windows, etc. * Bad new is that the turn-around time for the G10 order is 3 to 4 weeks. Ugh. * 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. * We need to make a decision on whether we will work with the supplier to preselect sheets or whether we will over order, building in a waste factor. We still need to finalize how many sheets will be needed for the full-scale prototype. These decisions are converging and we would like to be able to complete the PR in about 1 week. * The Rohacell order should include all pieces necessary for all wire frames, cathode frames, gas windows, etc. * The turn-around time for delivery is less than 2 weeks. - Storage: Kim had been amassing boxes of FDC-related components in her area. She will bring the boxes over to Simon for storage in F117 tomorrow. She has prepared lists of what is included in each box so that we can keep this information organized. We do want to get this information into a database. Perhaps Mark S. is the right person to maintain this information. - 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). We will get an update on this shortly, but it is not now a high priority.
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. * Bill has been working on gathering together all of the measurements and tolerances into a complete document. * We do not think that it would be practical in terms of time to machine the combined G10 skin + Rohacell core to height. This will be another branch of R&D that would take some time to develop. NOTE: after the meeting, Bill talked with Casey and he believes that he can machine the G10, epoxy, Rohacell laminate to a tolerance of +/- 2 mils. All that would have to happen is to modify our aluminum jig plate to enable it to work with our vacuum bagging system. This sounds attractive and the price is under $1.5k. We will talk more about this over the next couple of days and make a decision. * Bill and Mark have laminated together the six solder-sample PCBs. Photographs of this work are now in the FDC logbook (entry 382). * The thickness of the PCB laminate will be measured tomorrow in the lap joint region. The laminate will then be epoxied to one of our G10/Rohacell laminates using the vacuum-bagging technique to develop our procedures. - Fernando looked at the PCBs that came back from Greg Arnold's group and was satisfied with the quality. Herun has started to redo the electrical QA on the boards before construction. She will be done shortly and a full report will be provided. - The wooden shipping box will be shipped back to JLab by IUCF. They have gotten the paperwork from Lorelei and will get to this shortly. - PCB updates: * Kim has finished the moving of the decoupling capacitors on the back side of the STBs. Fernando is now looking over the design drawings to make sure all is well. * The updated PCB drawings will be given over to Bill so that they can be put into the 3D model.
- 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. The nitrogen dewar ran out because somebody stole liquid out of it without our consent (what a world, what a world). A second dewar has been put into place. - 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. - Roger was asked last week to make contact with our sales representative at Allflex. No word on if this has been done or not. - Bill has been working on the edge cutting system. We will talk about this in detail in an upcoming meeting as we will need this system in place before we can make any cathode planes. - Cathode flatness measuring system: * Micah has an injury that will not allow him to type so the flatness measurements have come to a halt. Herun was volunteered to help him out to get the measurements done. This is important to complete very soon so that we can move to select the desired cathode tension. - Brian is working on a first draft of a cathode construction document. He will pass this on to Bill early next week. - 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. We want to develop a better system. Also note that the next cathode we make should be set to a tension of 300 N/m (so sayeth all present). 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. An important point regarding board distortions. The amount of stretching for a given tension, depends on what the polyimide actually is. Keep in mind that what we have is not Kapton. It is Kapton-like, but it has different properties. More to come. - 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 Phase 2 winding paperwork has now been signed by the 12 GeV folks and passed on to our contracts people. The paperwork has been passed on to IUCF and they are reviewing it now. There is an issue with the start date and end date of the contract. DSC talked with IUCF about the current wire frame construction schedule. Our plan is to have wire frames to IUCF before the end of the year. The contract will reflect this information. - Roger needs to provide an update on the work to complete the Moire masks for the Phase 2 wire winding.
- We are presently focusing on two different choices for the material of the solid spacer. One is polypropylene and the other is Noryl. Noryl is more expensive, but may have less handling and construction costs. We need to do a price estimate. We can easily laminate Noryl to the cathode board and eliminate one o-ring. Polypropylene does not epoxy well and would need to undergo an acid etching step to better prepare the surface to receive the epoxy. Bill has started to look into this, but the soup of chemicals required has safety issues written all over it. - 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. - Fernando has posted GlueX-doc-1131 entitled "Electrical Characterization of the CDC and FDC Detectors". Folks should read this over and give feedback.
- The deadline for getting ASIC feedback to Mitch is very near. The specifications for the FDC ASIC are believed to be final. Waiting for Yves to complete work for the CDC. Our next FDC/CDC meeting will be on Monday to find out where we stand. - 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.