FDC Weekly Meeting
Date: December 10, 2009
Participants: Daniel, Mark I., Brian, Fernando, Tim, Chuck, Bill, Casey, Simon, Eugene, Beni, Roger
Next Meeting: December 17, 2009 @ 1:30 a.m.
General Construction Updates
- The two-layer version of the full-scale prototype was reconfigured after the gas sealing and spacer modifications. Great new, no leaks were detected after careful leak checks of the entire system were performed. - Signals from the second wire layer were checked and were fully consistent in all respects with those measured for the first layer last week. - The third wire layer was prepared for lamination to the second cathode sandwich and the lamination was completed. Casey completed additional sealing about the O.D. of the different layers of this lay-up. - Casey is in the process of preparing the third and final spacer ring using the pin-striping tape and the soft o-ring material. This will be ready first thing tomorrow. - The HV pigtails for the third wire layer will be soldered onto the board tomorrow morning in preparation for adding the third layer to the stack. - A short developed in layer 1 on the HVTB bus #4 between the field HV bus near the join between the two HVTBs and the sense wire it passed under. This had been fine yesterday morning during "final" HV check outs. Remember this had been covered with epoxy potting. Somehow a hard path was made through the epoxy from the -HV bus to the sense wire shorting out the supply (at 2 MOhm). We took the stack apart and alleviated the problem by removing the epoxy and removing the sense wire over the HV bus and repotting. The first two layers of the stack were then reassembled. - We will be ready to complete the full-stack assembly tomorrow before lunch time and then spend the afternoon leak checking. If all goes well, we will let gas flow over the weekend, and do final HV check out on Monday. We plan to move the full-scale prototype into the cosmic ray test facility as soon as we can (i.e. Monday or Tuesday). - The W&M folks sent back pictures and details from a first look at a sample of our CDC/FDC sense wire order. The wire looked good with a smooth surface and a uniform gold coating. There was some surface contamination on one of the samples (lines in C, O, and Na). This was after cleaning in an ultrasonic bath for 30 minutes. However, everything else looked good with no obvious ovality of the sample. The W&M group has our full set of samples from the 4 sense spools and 4 field spools. DSC will give them the go-ahead to proceed. Interested folks can take a peek at the sample photographs. - Bill will follow up on getting us access to an oxygen sensor to check the oxygen levels in our chamber outflow. - The preliminary FDC stack assembly document draft is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. The document will continue to be fleshed out during the assembly procedure for the full-scale prototype. We will have to add steps in our construction plans for leak checking.
Wire Frame Update
- We need to have a dedicated meeting to design what the schedule for work on the Phase 3 wire winding will be. The highest priority for work scheduling will be doing work on upgrades of the wire winding facility. This includes a better strongback design, the design and construction of precision combs, modification to the wire winding table, and a list of other items with the system. DSC, Bill, and Keith will work to have a meeting next week. - The wire frame construction document is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We will include the information on the wire electroplating process shortly. - The parts of the jig to use for the wire electroplating operation are in our hands. They will be assembled as we find time. - We need to prepare a document for the electrical QA of the preamp connectors on the wire boards. - DSC, Bill, and Fernando will plan a meeting to go over the circuit board design work with Kim. We would like to have this first meeting scheduled for next week. - Kim is following up with the contacts regarding large-area PCBs. Kim did not make a contribution to this week's meeting. DSC will follow-up with her. There are a host of worries about the time line depending on how long it takes to quality the board material and the vendor if we go down this road. Stay tuned.
- The current draft of the cathode construction document is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. - We need to prepare a document for QA/stuffing/cleaning for the cathode boards and a similar document for the cathode daughter boards and ground boards. - The order for the cathode material was scheduled to arrive on Dec. 26. Roger asked that it be held for delivery until the first week of January when shipping and receiving is open for business. Tim suggested that before we store away the board material, that we do an inspection and quick QA check to be sure that there are no obvious problems before we store the material away.
- Bill provided the specifications of his proposed design changes to improve the leak-tightness of the FDC system to Simon. Simon will prepare a new geometry file version for study of the new material impacts. It is not yet clear who will do this study. The last time this study was done was for the FDC review and systems review back in Aug. 2008, and this study was performed by IU. Beni will contact the IU folks to find what needs to be done and if they can complete the studies of photon conversions. - We had a bit of a heated (but good) discussion about the time line and work associated with validating the proposed changes. Tim believed that our current design, while we have gotten to a leak-free point in the current prototype with lots of work, will be a major labor sink for construction and may not work long term. DSC was worried about delays to our current time line and wanted to be sure that whatever we ultimately decide on for the FDC frames, we make versions for inclusion/test in the full-scale FDC prototype. * For the wire frame, the place is to include a thin solid G10 annulus in the middle of frame to replace a portion of the Rohacell. This annulus would go beneath the holes and the o-ring points. Overall thickness would be guaranteed with a fly cut just as we do now with the Rohacell/G10 laminate that is glued to the circuit boards. Bill will prepare a design drawing for the shop to get the pieces or pieces made and we can make up a frame using the solder sample boards. * For the cathode frames, a similar plan is in place to put a thin G10 annulus beneath the position where the o-ring sits at the location of the through holes. Bill will preapre a design drawing for the shop to get the piece or pieces made and we can use some of our mechanical cathode prototypes for construction. * We dicussed a bit whether these new annular inserts should be made from G10, but we didn't make a decision. We will most likely proceed with G10 pieces for our tests. * These studies have no impact on moving forward with the final circuit board design and procurement. Neither should they impact our moving forward with the final design of the cathode boards and their ultimate procurement.
- An order for more ASIC chips is expected very shortly. Fernando expects that we will have ~40 boards ready by the end of November.
Cosmic Ray Test Stand
- Several meetings ago we focussed on the wiggles seen in the reconstructed wire position from the cathodes (see log entry 419) in the FDC logbook. We believe that the periodicity seen is due to the algorithm Beni is using to determine the U and V centroids. Beni get back to this soon. Stay tuned. - We expect to install the full-scale FDC prototype into the test stand in the early part of next week to begin hooking it up and connecting it to the readout.
IUCF Phase 3 Meeting
- At the end of the FDC meeting, we had a phone conference with the folks at IUCF. That facility is going through a bit of a management/administrative shakeup. They plan on honoring work agreements that are already in place or are in place by the end of this year. As we will not have anything formal in place for Phase 3, our status is a bit uncertain. The IUCF folks asked us to prepare a "letter of intent" as to the work and the time line to make things a bit more formal. - We discussed the timeline for the start of Phase 3. We would like to see work begin formally on production winding on Oct. 1, 2010 (the start of the Phase 3 contract). They saw no problem with this. - We discussed that we will need some time during the summer to upgrade and test the wire winding system based on lessons learned during Phase 2. They agreed with this. - We also touched on the manpower issues. Keith will retire in Feb. 2010, but is committed to the Phase 3 project through its completion. Alan Eads' availability is not fully certain, but we would definitely expect that the one skilled/experienced technician is put on this project. We also discussed a temporary Hall D person assigned to the project stationed at IUCF for the duration. More to come.
- 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.