Minutes-8-27-2009
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FDC Weekly Meeting
Date: August 27, 2009
Participants: Daniel, Simon, Bill, Mark S., Stephen, Mark I., Beni, Eugene, Brian
Next Meeting: September 3, 2009 @ 1:30 p.m.
Contents |
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General Construction Updates
- Stephen Burnett from Hall B will be providing technical assistance to FDC prototype construction work for the next couple of months. He has been working with our group during the past week and getting up to speed on all things FDC. - The assembly jig on which the detector stack will be constructed will start to go together over the next several days and we will do some dry fits to be sure there are no problems. We are waiting for some parts to be delivered from the shop that are expected tomorrow. - Bill has begun work on the FDC stack assembly document. The draft will be made available after he completes a bit more work on it. The document will be fleshed out during the assembly process with relevant photographs. Stay tuned. - Bill figured out that the thin annuli for the gas windows can be laminated to the end cathodes before attaching the mylar windows. This will help to reduce stresses on this rings that were worrisome to him. The two gas frames are ready for attachment to the end cathodes.
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Wire Frame Update
- Mark S. has gone through Rich's notes and provided the data that he had recorded from the HV tests to give us a baseline to compare to. - We did HV tests on frame P1 after it sat in the dry room for nearly 3 weeks. We measured either 10 or 20 nA/bus for 11 busses and one was at 50 nA/bus. As these numbers were so different from Rich's last recorded numbers (we could not find final numbers in Rich's notes after his extensive cleaning efforts), we opened the tent up to re-expose the frame to the 60+% humidity of the room. After one day, the bus currents were 20 or 30 nA (with the one bus up to 140 nA). After another day, the currents were about the same. We decided that we would study the currents over the next several days to see how things evolve. We will probably do some additional cleaning and inspection to see if the one high current draw bus can be affected by our efforts. - In the mean time, Beni looked at the currents on frames P2 and P3 today. These frame also sat in the dry room for ~3 weeks and we opened up to the 60+% humidity yesterday. Here we were able (more or less) to reproduce the numbers that Rich recorded after cleaning. However, there seemed to be a steady decrease of the currents with time (on the scale of 3 -4 hours). The plan is to do some additional cleaning studies on a few of the high current draw busses during the next several days to see if we have any effect. - In the full-scale prototype, there was a design problem with the circuit boards so the wire frames will be laminated to their neighboring cathode planes to give a gas seal. We are hoping that frame P1 will be ready for lamination by the middle of next week if the leakage currents do not rise too high after letting it sit out over the weekend. We will decide how to proceed with planes P2 and P3 next week after more studies are completed. If Fernando is back next week, we will bring him into the discussion and planning. - We were worried about torques applied to the preamp card associated with the cooling loops. We will most likely improve the bonding strength to the wire frame by adding epoxy around the perimeter. We will investigate this when we get a bit further in prototype assembly. - 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. Stay tuned, more to come. - The wire frame construction document is located at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. He will include the information on the wire electroplating process as well. - The parts of the jig to use for the wire electroplating operation are in our hands. They will be assembled as we find time. - Brian received the SEM scans for our wire from the W&M folks. He will generate a final QA report with photos and test results for all wires when he gets a chance.
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Cathode Update
- Progress updates:
* Bill has all safety work in place to remove the epoxy from the
contaminated cathode. He has successfully cleaned the epoxy from
a full-scale dummy cathode and is planning to work on the real
cathode on Friday. Once the plane is certified clean, we will scan
it for flatness and attach the ground plane and gas window.
* This past week we have finalized the procedures for putting the gas
holes in the end cathode ground planes. The ground planes were attached
to the tensioning frames. One ground plane was tensioned, attached to
its end cathode, and the lamination of the annulus for the gas window
will be completed this week. The gas window will be attached early
next week. The second end cathode, ground plane, gas window frame, and
gas window assembly will be completed next week.
* We are now ready to begin soldering the rigid-flex assemblies onto the
cathodes. Still waiting for them from the electrical QA step.
- The parts for the QA system for the rigid flex assemblies should all
be in hand this week and probably assembled tomorrow. Testing and
certification will take place next week. We will most likely have to
supply the manpower for these tests.
- We will be investigating strain relief design for the ground pigtails to
be sure that they cannot be over stressed and ripped off.
- In the next few days, Roger and Mark S. will have to get together and
start soldering rigid-flex assembly boards to test cathode pieces to
finalize the procedures. We can use the old (flipped) flex assemblies for
this test soldering. We are eager to get started on the soldering work so
that stack construction for the full-scale prototype can get underway soon.
- Bill would like some additional design work done on the cathodes to give
more space between traces and holes. He sketched out his concerns, but we
will need to have a separate meeting with Roger to find a solution.
- Bill has been working on the cathode construction document building in
the pictures that are being taken. The current draft of the document
is located at /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We need
feedback from folks involved in the process to be sure that all steps
are included and accurately detailed.
- We have heard that the Japanese company that made the polyimide with for
our 2 micron Cu boards has agreed to provide the material for our
detector. They expect to be able to complete the order by the end of this
year. DSC will talk to Roger about moving on with the purchase.
- 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.
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Cooling System Tests
- Fernando is in the process of writing up the results from his cooling system studies. Stay tuned for the GlueX note. He indicated that he is back to work on this document and it should be done shortly.
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Cosmic Ray Test Stand
- Beni is continuing work to setup the cosmic ray telescope and test system in EEL 126. He is making progress on reducing the noise and is working to reproduce the data from the small-scale prototype that Simon had last year. - We still have some mysterious behavior with the small-scale prototype response with wiggles in the X vs. Y distributions that need to be understood. Beni has reproduced this problem qualitatively and we discussed some possible causes, but more work needs to be done. - Beni has started a bench test plan for the full-scale prototype and is presently working on it after incorporating feedback. The current information is contained on the FDC wiki page under the heading "FDC test cosmic ray test stand". - The parts for the support/rotation of the full-scale prototype in the cosmic ray stand will be assembled as we have time.
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Work List
- 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.
