Minutes-2-12-2009
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FDC Weekly Meeting
Date: February 12, 2009
Participants: Daniel, Beni, Mark S., Eugene, Simon, Brian, Elke, Mark I., Fernando, Bill
Next Meeting: February 19, 2009 @ 1:30 p.m.
Contents
Full-Scale Prototype Updates
- Procurements:
* We want the remainder of the cathode order to go out by the end of this
month. This sets the time frame for the redesign work Roger is doing.
The plan is nominally to order 6 more full sets of 2 micron boards and
2 full sets of 5 micron boards. If there is money available, it would
not be bad to order a couple more sets of 2 micron boards as we will need
several for R&D work.
- Chamber Wire:
* Brian has provided samples of our sense and field wires to the SEM folks,
they will complete the mass spectroscopy analysis. As we have not heard
anything for a while, Brian will check in with them.
* Brian will prepare a final QA report with photos and test results
for all wires when all studies are complete.
- Mark S. is also responsible for upkeep of the list of procurements for
the full-scale prototypes.
* Location: M Drive/halld/Electronics, or for more sophisticated folks,
/u/group/halld/Electronics.
- DSC has talked to the Hall A representative Bogdan Wojtsekhowski about sharing
the clean tent. We gave them use of the tent this week and will take control
back early next week. Hopefully the group will be done with their work during
this period.
- A bottle neck in our prototype construction is that we have only one cathode
board tranfer ring. Bill will prepare a drawing for the shop and work to have
a second frame constructed.
Wire Frame Construction
- IUCF is now working on a technique to check the relative positions of the sense and field wires on the winding table to eliminate the systematic 40 micron offset that we saw last time. They should be sending around some preliminary measurement data this week and we will set up a phone meeting to talk about progress and schedule in the next couple of business days. - Nominally Bill will go to IUCF for the week of March 16. If this moves up, IUCF will give us a heads up so plans can be made. - To remove the problem with glue wicking up through the vias in the PC boards, we have asked Kim to reduce the size of the vias (to eliminate the openings) and to cover the vias with the solder mask material. This amounts to a belt and suspenders approach. - Bill has designed a wire frame protective cover that will be in place during the Phase 2 component stuffing. This cover is in the shop now being machined and will be done shortly. We may also design a turntable for the solder technicians to use with the wire frame for this task. - Mark will update the wire frame construction document based on lessons learned from the prototype frames. A new version will be posted when his work is done. - We plan on performing the electroplating technique with at least a couple of our full-scale prototype wire planes. We will do some more practice on the Phase 1 winding planes to finalize the technique and to prepare a procedures document.
Cathode Construction
- We reviewed the cathode R&D timeline. Folks are reminded to pass on
progress updates to Chuck every Wednesday. The current schedule is
being kept on the mdrive at:
* Location: M:\halld\Individual-Schedules\FDC or for more sophisticated
folks, /u/group/halld/Individual-Schedules/FDC
- We spent some time reviewing the basic cathode design and where the nominal
tension number of 500 N/m came from. Whether the final value ultimately
is lower or higher remains to be seen. It depends on the half gap, the
quality of the cathode boards, and the glue seams.
- Progress updates:
* The cathode edge cutting system continues to be tested. The system seems
to work well. Bill and Mark have made some test cuts with our dummy
cathode boards and are looking at them with a camera mounted to a mill
in the JLab machine shop. The edge looks well defined to the level of
+/- 3 mils. Work continues to improve the cathode positioning procedure
relative to the cutting blade. We are trying to rig up a camera to allow
us to easily view the position of the cutting head relative to the edge of
the strip along the full length of the board. A few small pieces are in the
machine shop and should be in our possession shortly. Hopefully we will be
far enough along to test cut one set of the 5 micron "real" boards next week.
* No progress on completing the cathode construction document. Stay
tuned.
* We are working to prepare three G10/foam laminates for prototype cathode
cathode boards. The first is now out of the machine shop and had the
second G10 annulus laminated on. There was a problem with the jig plate
used for the vacuum bagging that added a distortion to the frame. It should
still be perfectly useable for the mechanical tests. A new base for the
cathode vacuum bagging procedure has been prepared in the shop and will be
used for our next frame. The first frame is now being machined to include
the gas through-holes. This frame should therefore be as realistic as
possible.
* Today the Kapton cathode membrane that is in the tensioning fixture set to
500 N/m will be attached to the frame. This procedure will use weights placed
on top of the frame to apply pressure. Ultimately Bill would like to use
pressure applied by one or two air bladders. As we do not want to wait to
proceed, we will likely go the air bladder route if the frames survive the
mechanical loads. Tomorrow we will see if the frame handles the tension load
of the membrane and measure the in-plane and out-of-plane distortions.
We will make up a second frame on Monday or Tuesday of next week. The
associated Kapton cathode membrane for this frame is already put together
and rolled up for storage. Brian used the cathode edge cutter to make
a three piece panel for the second frame.
* Roger has completed modifications for one of the three cathode panels
to allow for stretching perpendicular to the strips of up to 4 or 5 mm
and parallel to the strips of 2 to 3 mm. He sees no problems modifying
the other two boards. We need to get a progress update on this work as
Roger was not present today. We want the remainder of the cathode order
to go out by the end of this month.
* We discussed plans for using an optical system to measure the
cathode board distortions after they have been tensioned. Presumably
we could use the horizontal mill in the machine shop using their
camera system. This will most likely be needed in about 6 weeks.
* The clearance issue that Bill raised at our last meeting between the
cathode daughter boards between neighboring layers in the middle of the
cathode sandwich can be solved by flipping the artwork on the cathode
daughter board cards. Bill has verified this will work for all clearance
issues. Roger will go ahead and make the necessary changes.
* Brian has tried to find a roll of 12.7 micron aluminized mylar for our
ground plane material but is not having luck so far. All we have on hand at
present is 6.3 micron material and we will use this in the mechanical
cathode sandwich prototype.
* We will need to place an order soon for more G10 annuli for the cathode
frames (the larger pieces). Bill will put together a PR shortly after
Mark checks our inventory. This is confusing as we should have ordered
all of the necessary G10 stock with our last order in December.
- We discussed how we want to store the cathode frames after they are made. The
consensus was that they should like be stored locked into a flat position. We
should avoid unnessary flexing of the frames from the flat to distorted positions.
Cathode flatness measuring system
- Documentation of the system continues. See the FDC wiki page for details. - Brian has completed a PR for a second laser for the FDC work.
Spacer Design
- The spacer frames are now under construction in the JLab machine shop. They should be in our possession very shortly.
Stack Assembly Procedures
- DSC, Brian, 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 used to compress the stack. We will be receiving some samples shortly and will carry out some loading tests.
Cooling System Tests
- Fernando is in the process of writing up the results from his cooling system studies. Stay tuned for the GlueX note. - Bill has done some ANSYS modeling to better study the connector that goes from the daughter board card to the cooling loop. These will be added to Fernando's note.
Documentation
- 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.
Cosmic Ray Test Stand
- We will be moving the FDC cosmic ray test stand from the Test Lab back to the EEL building. This move should be probably take place in April. - 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. - We would like to put together a bench test plan for the full-scale prototype within the next couple of weeks. This preliminary test plan will be used to provide information on what test stand fixtures to support the chamber we will require. Bill can then work on the design and get things prepared in the shop. Also, we would like to layout a design for the electronics before too much longer so that we can reduce time from when the full-scale prototype is constructed to when we get into the test plan.
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.
