Minutes-9-24-2009
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FDC Weekly Meeting
Date: September 24, 2009
Participants: Daniel, Bill, Simon, Fernando, Beni, Eugene, Brian, Glenn, Mark S., Mark I.
Next Meeting: October 1, 2009 @ 1:30 p.m.
Contents |
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Manpower Update
- Manpower will be thinning out soon. Stephen Burnett has gone back to Hall B. Brian Kross will be off the project for the month of October. We will have to rally available manpower to finish (and start) stack construction. Stay tuned.
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General Construction Updates
- We are presently gearing up to begin stack construction for the full-scale prototype. Stay tuned for news and the associated press release that will inevitably follow. As part of stack construction, we will do a 3D voltage check with a cathode-wire-cathode configuration in an Ar-CO2 gas environment to nominal voltage to be sure that there are no breakdown problems. - Bill has been working on the FDC stack assembly document. He has made a draft availale at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. Folks should look it over and provide feedback. The document will be fleshed out during the assembly procedure for the full-scale prototype. - We will proceed with regular solder for the rigid-flex soldeing for now. Brian will follow up to see if we can get a sample of Indium solder paste. - This past week we sealed a single wire board in an Ar/CO2 gas environment similar to the configuration of the real FDC detector. Several nominal size o-rings were made and used and it turned out to be a big problem to keep them in their grooves. Several lessons were learned about how to make this easier to work with during stack construction. Two approaches that we are pursuing are to use a Gortex gasket with adhesive on the back and to make a v-shaped o-ring slot to capture the o-ring. Bill has ordered some sample gasket material and the JLab shop is making up a test o-ring. Stay tuned for developments. - We have to be out of the clean room by October 15. We will investigate way to bring the clean tent into room 126 and set it up there.
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Wire Frame Update I
- Wire frame P1 status:
* Frame P1 has had its high voltage components fully sealed in
Humiseal after drying out in the tent for several days. The currents
were found to be acceptible on all busses. After the meeting, Bill
machined in the pockets for the clearance of the rigid-flex assemblies
on our single screwed up cathode. The mission was apparently successful.
A voltage check will be done tomorrow and the frame will then be ready
for lamination to its associated cathode plane (this cathode still
needs to have its rigid-flex assemblies soldered into place).
* Due to handling, one of the preamp card connectors was broken and
will need to be replaced. Also one of the low voltage power connectors
was broken off and several of the contact pads came with it.
- Wire frame P3 status:
* Frame P3 was set up such that its active area was setup in an
Ar/CO2 gas environment, but the rest of the wire frame was left in
air (just like the nominal configuration). Due to problems with getting
a good gas seal, Snoop was squirted liberally on the boards. Snoop
appears to be a pretty good conductor, and the currents on the HV
busses rose to a level that the busses could not be even turned on
to 10 V. After initial cleaning, the problems were slightly improved,
but still horrible. In taking apart the gas setup to allow for access
for cleaning, 3 wires were broken. Brian has replaced 2 wires and has
one more to go.
* We did get some encouraging news before the Snoop problem had taken
hold. Beni measured the currents on some of our worst busses after
gas flow had been going for about an hour and found them to be very
low. However, full measurements and checkout was not finished before
the Snoop wicked its way around the board and ended hope of doing
sensible measurements.
* At present we are still working to clean P3 and continue the gas
tests. We are now moving to set up a system to clean the board more
fully in alcohol and deionized water. We hope to have something set
up in the next couple of days.
- Wire frame P4 status:
* P4 has current draw problems similar to P3, maybe a slight bit better.
We only have current draw information at normal room humidity and we
have let the board sit in the dry tent for a while. We will inspect
the board and make current measurements when we get time. We will then
do the gas test similar to what we did for frame P3.
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Wire Frame Update II
- 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 will move forward with this work as we certify each wire frame as ready. - 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:
* The mechanical work on all cathodes is complete. The last thing
to do is to connect the grounds on the individual panels on each
cathode. A first attempt was made, but Fernando is not fully
satisfied with the contact area and we will revisit it.
* Lots of problems were found with the rigid-flex assemblies during
electrical QA testing. Fernando was not pleased and took the boards
back for additional checkout, repairs, and cleaning. He has since
certified a number of boards and made them ready for soldering to
the cathodes. The remainder of the rigid-flex assemblies should be
provided for soldering shortly.
* Mark S. has not done any additional test soldering over the past
week as we were awaiting a new heat sink from the shop. It is now
in our possession and Mark S. will return to finalizing the soldering
technique on test pieces. Certification of the soldering technique
still needs to take place before work with the real cathodes can begin.
- The current draft of the cathode construction document is located at:
/u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
- Roger is pressing the Japanese company that has agreed to provide our
board material. They have agreed to manufacture the material and it
appears it will be delivered to JLab by the end of this year.
- 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. The latest plots are in the FDC electronic logbook at: http://www.jlab.org/Hall-D/detector/fdclog/ - 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 just completed a pulser calibration run and his look at the small-scale prototype data including the new channel-to-channel gain matching (albeit with low statistics) looks very promising. Perhaps the wiggles are gone and can be blamed on the calibration. - 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.
