FDC Weekly Meeting
Date: February 11, 2010
Participants: Daniel, Simon, Beni, Eugene, Lubomir, Mark S., Bill, Kim, Brian, Fernando, Glenn
Next Meeting: February 18, 2010
General Construction Updates
- The two-layer prototype continues under source tests in the cosmic ray test facility. When we want to open this up to investigate the several HV bus problems and to consider adding the third layer remains to be determined. Stay tuned. - We are proceeding slowly with the repairs of the third prototype layer (cathode sandwich with laminated wire plane). Casey and Mark are working on sealing the 24 through-holes with epoxy. They are still trying to optimize the procedures and have filled about half of the holes so far. We then will have to decide how to test this layer for the leak that we believe remains in the ground plane (and try to understand how the leak appeared in the first place). - The oxygen sensor does not appear to be functional after several quick checks. Brian will take care of sending it out for repair and calibration. - The preliminary FDC stack assembly document draft is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We will review this document in the coming weeks to update out-of-date or old procedures.
Frame Modification Studies
- The inner frame pieces for the wire frame and cathode frames were delivered by the JLab machine shop. They were not particularly well made, but we were able to make some changes and got them to fit. They have been glued up into annuli and had their seams filled with epoxy and sanded down. They are ready to go. - One dummy cathode board made from three pieces of Kapton has been laid out and attached to the tension transfer frame. We are out of material for further dummy cathodes. More material has been ordered and will arrive next week to prepare a second dummy cathode. - G10 skins for the cathode frame are back from the shop and we are ready to laminate the frame filler pieces to the G10 skins and to add the Rohacell core. These two pieces (one for each cathode of the cathode sandwich) will then be sent on to the JLab machine shop to be fly cut to the final thickness. The frames will then be ready to attach the dummy cathodes. Then they will be laminated together to form the cathode sandwich. - Bill has had a G10 skin prepared for the wire frame. It is back from the shop. However, he also has the shop making a G10 piece that basically combines the G10 skin + filler pieces in one. This should be back from the shop in about a week and is will be laminated to the solder sample boards. This design looks like it will become our nominal design choice based on its design and its preliminary pricing information. - Bill has put together a few slides showing the frame design changes.
Wire Frame Update
- The wire frame construction document is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. - Casey has worked on a QA document for the preamp card connector checkout and will post it shortly. - Kim is still working with a board house (Trilabs) to get us meaningful quotes for single piece circuit boards (either one single annulus or one HTVB and one STB per frame). - We met with Kim to review her work on final redesign of the wire frame PCBs. She has made good progress on making the required design changes to one STB and one HVTB. She is nearly ready to move to the second STB and HVTB. - Kim provided drawings regarding the geometry of the glue strip area and the solder pads, as well as a layout of the proposed wire layout fiducials. DSC passed these on to Keith Solberg at IUCF for comment.
- The current draft of the cathode construction document is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. - Casey is preparing a document for QA/stuffing/cleaning for the cathode boards and a similar document for the cathode daughter boards and ground boards. He will circulate it shortly. - In order to officially accept the cathode board material, we have asked for the company to provide a sample piece for us to test. The sample has arrived at JLab and we will measure the surface resistivity before signing off on the material. - The next rigid-flex design meeting will take place later this month. - We would like to push to get the cathode board procurement done on the time scale of this March. Stay tuned. - David Lawrence is working to give us input on the hole size in the cathode center. Stay tuned.
- The current version of the full-scale prototype test plan is on the GlueX portal as (GlueX-doc-1304). - A while 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. Stay tuned. - To connect the full-scale prototype to the readout electronics, Fernando will design a simple translator board that allows connection from the 24-channel preamp connector to the 16-channel connectors on the ADCs and TDCs. These boards should be ready in the next few weeks. - The signal cables for the full-scale prototype are being made up by Fernando's group and should be ready shortly. - The two-layer prototype has been under tests for several weeks. Beni has been measuring plateau curves and studying efficiencies. You can look in Beni's directory for more recent test results. - Beni has been having trouble with current draw at HV that seems to be appearing after the bus seems to have behaved for a little while. Beni will look into reverse biasing the chamber for some additional cleaning. We may try to fill the chamber with nitrogen and try to separate problems with the wires from problems with the boards. - Beni will be including the cathode preamp card and hooking it up to ADC readout shortly. - Fernando will pursue purchasing enough cathode ground boards for all six cathode planes for the full-scale prototype.
- Two wire spool samples have been studied and reports have been provided. The reports have been posted at: S3 Samples and S4 Samples. Comments are welcome. - Keith Solberg at IUCF is reviewing the preliminary Phase 3 FDC budget and expects to have us an update in about a week. He will also provide a budget estimate for the summer wire winding facility work. DSC and Bill are working on planning for the summer work. Once we have a Phase 3 budget that is reasonable, we will move forward with developing a formal statement of work for Phase 3. We expect significant progress on this front by the end of this month. - It is time for the next Phase 3 preparation meeting with Keith Solberg, Bill, and DSC. DSC will work to schedule this only after we have a preliminary Phase 3 budget in our hands. See the work plan at: Phase 3 Preparation Work - Master list on wire and cathode frame redesign work is located at: Frame Modification Work. - We talked a little bit on the gas handling system for the Hall D chambers. It is not fully clear exactly what we want to build, but we agreed to have a few offline discussions to try to come to some level of convergence. Beni will give an update at the next Tracking Meeting to get Curtis' input.
- DSC will prepare a brief write-up with input from Bill on what we plan to use the mechanical prototype. This will give us some idea of how important this prototype is, when we want to put design effort into it, and the level of complexity of this system. Stay tuned.
- 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.