FDC Weekly Meeting
Date: August 14, 2008
Participants: Daniel, Simon, Brian, Tim, Fernando, Bill, Micah, Herun, Mark, Jim, Beni
Next Meeting: August 28, 2008 @ 1:30 p.m.
- 1 Manpower
- 2 Readiness Review
- 3 Cathode Planning
- 4 Cathode R&D
- 5 Cable Procurements
- 6 Machine Shop Work
- 7 Wire Frame Construction
- 8 Test Frame Wire Winding
- 9 Spacer Design
- 10 Stack Assembly Procedures
- 11 Cooling System Tests
- 12 Gas System Design
- 13 Documentation
- 14 Small-Scale Prototype
- 15 CAD Model
- 16 Work List
- It has been announced officially that a new technician is joining the Hall D group. Mark Stevens, who had been in Hall A, will be starting with us on Monday. He will be assigned to work mainly on the FDC prototype design and testing.
- The planning for the readiness review is underway. The idea (tentatively) is to schedule the review for next Thursday (Aug. 21) afternoon. If folks feel that they cannot be ready on this time scale, we will work to push it back an additional week. - The main topics for discussion and their presenters are: - Wire frame design : Bill (assisted by Brian) - Cathode R&D planning: DSC (assisted by Chuck) - Cathode frame design: Brian (assisted by Bill and Eugene) - Assembly construction: Tim (assisted by Bill and Brian) - The review will be informal in the sense that it will be just internal JLab/Hall D folks participating. However, the talks should be powerpoint or pdf presentations. Be sure that all required test results, calculations, models, drawings, figures, and photographs are included in your presentations or brought to the session. - A more complete listing of the subtopics for presentation are given in a planning document. Please talk to DSC if you have any questions. This review represents our highest short term priority and folks should ask others for assistance as needed to cover all of the defined talking points. - More details will be sent around soon, but nominally we will replace the FDC meeting with the readiness review except that we will go longer into the afternoon. I would hope that each of the 4 major topics listed above can be scheduled to be for about an hour. - DSC will be talking to folks next week as well to see how they are coming along.
- The cathode boards should be shipped to JLab today. We expect that they will arrive at JLab before next week is over. Shipping and Receiving has gotten instructions not to open the transportation box. This will be done in the clean room. The cathodes will not be removed from the box until we have our own handling instructions in place. All relevant folks will be on hand for this event. - In preparation for opening the cathode box, the clean tent will be made clean and all supplies needed to carry out the QA plan devised by Fernando (GlueX-doc-1082) will be gathered together. - The shipping box will be modified after its arrival to include gas fittings so that we can flow nitrogen through the environment. The addition of the gas fittings must be carefully planned out to ensure that no damage is done to the cathodes and no dust gets into the transport/storage box. - Bill spent some time during the past week laying out some preliminary drawings for a system to cut the edges of the cathodes. We went over his plans and the planned cutting procedures. One area of focus is that we want to be able to sight the cutting head along the edge of the cathode strip to allow for precision alignment. Bill is nearly ready to prepare the PR for this system. We will be able to test it on existing pieces of the dummy cathode boards to finalize how well this system works and to devise the edge cutting procedures. any progress this past week on designing the system for the cutting of the cathode edges. He will return to this work when he has time. - Roger plans on preparing an order for the new cathode rigid flex assemblies with the copper fingers (cathode boards and cathode ground boards). This procurement will be completed by the end of August after Roger completes some additional design work. We will need a minimum of 60 rigid flex assemblies (not the 54 reported in last week's minutes) for the full-scale prototype. We will get a quote for these as part of the ordering process, but we are looking at a charge of roughly $5k (including board stuffing) for this order. - We did not have time in this meeting to talk about cutting holes in the cathodes (gas holes and central beam hole). This is an important issue that we will have to seriously consider. The worry is about losing tension in the cathodes if the holes (especially the big central hole) is cut after the cathode is tensioned. This work is an important part of our upcoming R&D planning for the cathodes.
- DSC is working with Chuck to put the cathode R&D work into an official project schedule. We have a preliminary time line laid out and are now working on finalizing the required ordering of the tasks and the manpower assignments. This work is required so that we respect the FTE assignments of various folks to the project and that there are nominally 8 hours in a work day. We will work to post this schedule very soon so that we can use it as our official project guide and tracker. We will work to incorporate contributions from the new technician as well. DSC is having trouble with the scheduling software and/or input file provided by Chuck. Additional work will have to wait for Chuck to get back from vacation. - Cathode flatness measuring system: * We are waiting for the parts n' pieces to arrive. We have about 1 week until they show up (roughly). * The system will employ an old granite table that is now in the Physics Storage Building and is ready to be moved to EEL 126. This table (4 ft (w) x 6 ft (h) x 1 ft (d)) will be used to support and to define the flatness of the cathode support ring. Bill will ensure that all relevant safety issues are dealt with in the design. * Bill is planning on overseeing the assembly of the system once everything shows up. * Bill has a number of smaller parts for the project that have been submitted to the FSU machine shop. These parts should be ready before the end of August. * Micah reported on work that he has been doing to generate contour plots of the surface flatness from the 2D data. He will send around samples shortly. * We will have to work out a time-sharing plan for the laser measurement head for the flatness measurements and the tension measurements. - Eugene is working to define the allowable surface flatness variations for the cathodes. What can we tolerate and still deliver a system that an meet the resolution requirements for the cathodes and the wire plane? Eugene should provide some answers by the end of August. - Brian and Bill should begin to layout a detailed outline for the cathode construction steps and circulate for feedback.
- Fernando and Kim will work to put together the PR for the manufacture of the LV cables needed for the small-scale prototype and the connectors for the signal cables. We have the signal cable material and the tool for crimping on the connectors. The plan is to have the LV cables made by an outside company and to make the signal cables ourselves.
Machine Shop Work
- The modification to our aluminum assembly jig is complete and it is now sitting in EEL 126. The new aluminum assembly jig is also complete and is now in the EEL clean room. The machine shop is finishing making up the dowel pins that screw into the jig plate. Brian has test fitted the STBs and HVTBs onto the jig plates and has reported that everything fits properly and the clearances are adequate for all components. - Bill has prepared all of the necessary material to submit the modifications of one of our prototype wire frames to the shop for a new load test. No further wire frame machine shop work will be submitted until the new round of load tests has been completed.
Wire Frame Construction
- The frame that was used for our wire tension load test (which is discussed in the FDC TDR) has been under the full nominal wire load for about a year now. This frame will be modified to include the pockets for the rigid flex assembly and the bolt holes. It will be machined to the nominal I.D. and O.D. of our wire frames. The foam core and the G10 skin will be removed to an I.D. of 1032 mm to account for the problem with the HV decoupling capacitor placement (discussed in last week's minutes). The plan is to redo our loading tests and measure the in-plane and out-of-plane distortions of the wire frame up to a load of roughly 50 lbs (the full wire load is about 35 lbs). We still have some details to work out on the test plan specifics, and this will happen before the tests and after we think a bit more about the modified frames. If Tim has time, he will work through some FEA calculations. - The pockets that we were originally planning to include in the back of the G10 skin of the wire frames have disappeared in favor of much more straightforward milling machine cuts. This will become our nominal design if there are no problems with the new load tests. - The nominal wire frame construction plan devised by Brian will be our starting point for construction. Folks should look this plan over in some detail and we will step through it before the start of construction to make sure that no steps are left out. - We are presently planning on borrowing an A-frame for EEL 126 for the wire frame construction (that Tim arranged). However it was reported that there may be some usable A-frames in long term storage (Blue Crab) that could be ours. This would eliminate having to share an A-frame with another group (which would be a pain for us and could impact our construction schedule for the full-scale prototype). - Simon and Herun are working to complete the HV checkout of the STBs. Some details are included in the FDC logbook entry #377. They have tested 4 sets of boards and have 1 more to go. Only 2 suspect capacitors have been found that need to be replaced. - The HVTBs will be tested next. At present some of the filter capacitors that have been soldered on will not be possible to leave on due to the fact that they will get in the way for wire winding. Fernando will work to get them removed. Once these few capacitors are removed, these boards will be Ohm'd out (to check the HVTB resistors). - The PCBs for the FDC will need to be handled by all folks involved with more care. Many of the boards have sustained damage to the fragile lap ends. The damage is not severe enough to cause any construction worries, but handling procedures do need to be established and followed. - Brian is working to put together an order for another spool of sense wire and another spool of field wire. DSC will finalize the wire specification document. It would be nice to use this with the vendors now and get the kinks worked out so that the specifications for the final detector wire order can be worked out.
Test Frame Wire Winding
- IUCF has completed the wire winding of an additional frame and has completed the wire position and tension measurements. For the wire position measurements, things look much better than the last attempt. However, there is an offset in the positioning of the field wires on the frame relative to the sense wires of about 40 microns. Keith is now reviewing the procedures used and we will work to rectify this problem. The wire tensions show a systematic drop from the frame edge to the middle. This may be due to the fact that the frame is now loaded and is warped. Tim will provide an estimate for the length decrease due to the load to check whether this is consistent with the IUCF measurements. - As the time to complete Phase 1 and Phase 2 winding before the end of the fiscal year will be super tight, DSC will work with Elke to complete as much of the required Phase 2 paperwork as we can in the next few weeks so that we can move quickly to getting Phase 2 in place before time runs out.
- It is looking like a CH2 spacer is becoming our nominal design choice instead of a composite design. During the past week, the machine shop cut a straight o-ring groove into a sample piece of G10. The edge was crisp and well defined. Machining does not seem to be an issue whatsoever. - Bill raised a concern about the different differential expansion of CH2 relative to G10. Bill stated that for an unconstrained CH2 spacer, a 40 deg change in temperature would result in a 3 mm size change across a diameter. Some calculations will be done and Bill would like to have a full-size CH2 spacer made for testing.
Stack Assembly Procedures
- DSC, Brian, Tim, 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 use to compress the stack. We will be receiving some samples shortly and will carry out some loading tests.
Cooling System Tests
- Bill and Fernando completed the planned cooling system measurements for the daughter boards. Fernando is working to put together a document of the test results. He indicated that no further cooling system tests are planned until we have more cards and can test a bigger portion of the system. So far, things are working according to expectations.
Gas System Design
- Slava is working 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. Slava provided some drawings that DSC will review. We will then 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 needs to provide an instructional writeup for the Phase 1 and Phase 2 wire frame PCB component attachment. This is on her to-do list, and DSC will talk to her about getting this writeup done.
- Simon and Fernando are in the home stretch on completing the specification of the cathode and anode ASIC dynamic range. All required measurements have been completed and work is ongoing to finalize the test results in the document. What we have so far is posted as GlueX-doc-1070. - 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.
- We discussed a bit about making sure all relevant design features of the FDC are in the full CAD model. Tim will have Slava work to put in the capacitors and resistors on the wire frame PCBs into the model.
- 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.