Difference between revisions of "Minutes 2-21-2008"
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* Take care of all cathode daughter board QA and board checkout for certification before installation in prototype. | * Take care of all cathode daughter board QA and board checkout for certification before installation in prototype. | ||
− | * Arrange for cathode daughter board stuffing at JLab (talk to Kim | + | * Arrange for cathode daughter board stuffing at JLab (talk to Kim as she is arranging this for the wire plane circuit boards). Develop stuffing and cleaning procedures document (consult with Fernando who is preparing a similar document for the wire plane circuit boards). |
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− | * Finalize cathode ground pour definitions and design to avoid | + | * Finalize cathode ground pour definitions and design to avoid anycathode current loops for protection from eddy currents induced with solenoid magnet quench. |
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− | * Finalize plans for connecting external ground to cathode boards | + | * Finalize plans for connecting external ground to cathode boards (consult with Fernando who is developing a plan for the wire plane and ground plane connections). |
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− | * Take the lead in the procurement of the cathode boards and the | + | * Take the lead in the procurement of the cathode boards and the cathode daughter boards |
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* Act as the contact for the cathode daughter board stuffing. | * Act as the contact for the cathode daughter board stuffing. |
Latest revision as of 11:49, 22 February 2008
FDC Weekly Meeting
Date: Feb. 21, 2008
Participants: Daniel, Mark, Simon, Brian, Kim, Chuck, Roger, Fernando, Bill
Next Meeting: February 28, 2008 @ 1:30 p.m.
Contents
- 1 Test Frame and Prototype Wire Winding
- 2 Full-Scale Prototype
- 3 Grounding Issues
- 4 Composite Cathode Discussion
- 5 Cathode Board Issues
- 6 Gas Volume Definition
- 7 STB/HVTB Issues
- 8 Cooling System Update
- 9 Small-Scale Prototype
- 10 FDC Mini-Review
- 11 Cathode Daughter Boards
- 12 Cathode Flatness Measurements
- 13 Meeting on LV/HV System Design
- 14 FDC Insertion Planning
- 15 Upcoming Reviews
- 16 Drawings
- 17 Work List
Test Frame and Prototype Wire Winding
- IUCF has just responded to JLab and they have provided a budget for the Phase 1 and 2 wire winding. It sounds like things are moving along and word will be sent around once we have a signed contract.
Full-Scale Prototype
- Elke has now given us a budget for construction of the full-scale prototype. The total amount is $150,000. This number is consistent with the budget estimate that DSC provided to Elke for construction of half of a full FDC package (U/V/W layers). - The procurement effort for the full-scale prototype is now proceeding in earnest. Kim has prepared a PR for the wire frame components and connectors that Elke has already signed. The PR for the wire frame circuit boards is now out for quotation and we expect a response by tomorrow. We will plan on order 5 full sets of circuit boards. Elke is ready to sign the PR as soon as our quote comes in. - DSC needs to provide Kim a handling and transport requirement document for the wire circuit board order. - Brian will prepare several PRs for the frame construction. This will include the G10 rings for the cathodes, wire frames, and spacers, the Rohacell foam for the cathode frames (4 mm thick), the spacers and wire frames (3.4 mm thick), and or the cathode backing (2 mm thick). - Brian will also prepare a PR for the construction of a second assembly station. This includes a second granite table and aluminum jig plate. This second station is essential to enable us to complete the construction of the prototype by June. - We are working with Roger to complete the design and layout of the cathode boards in the next 2 weeks (or less) so that procurement of the boards with 2 micron thickness can commence.
Grounding Issues
- The grounding scheme of the wire frame circuit boards has been settled. We have been sure to design the grounds so that the wire frame circuit boards do not present a current loop for protection from eddy current forces in case the solenoid quenches. The ground will be defined from an external source and single small spade connector will be soldered to each board. - The connection of the ground to the aluminized mylar ground plane is defined in principle, but the plan must be prototyped. Currently we will use the same spade connectors as for the wire frame ground. Several of these space will be included on the back of the cathode board G10 support skin using an epoxy connection. The two sides of the aluminized mylar gas window will employ conducting epoxy to make the ground connection. - The grounding scheme for the cathode was also discussed. The situation is a bit more tricky mechanically and we are looking to distribute the external ground to the cathode board ground pours through the cathode daughter board and rigid flex cables (being sure to keep this ground separated from the preamplifier daughter board ground). Roger will work with Fernando to finalize the specification. - For safety reasons we have decided to replace the 6.3 micron thick aluminized mylar ground plane with a 12.7 micron thick aluminized mylar ground plane. This was done to minimize the possibility of the ground plane (which is also a gas barrier between neighboring layers) of blowing in the case of overpressure.
Composite Cathode Discussion
- Brian has completed the construction of a composite cathode board. This board employed a butt joint between neighboring dummy cathode boards and a 2-mm thick low-density Rohacell backing. The foam core in the support ring was 5-mm thick (instead of the nominal 4-mm). Simon will put a photograph in the logbook. A couple of observations about this board. One is that this composite cathode has no degree of sagging or bulging when in the vertical position. Also the butt joint approach that Brian employed looks absolutely beautiful. The three piece circuit board really looks like a single board. Finally there were some noticeable wrinkles in the Kapton on the G10 skin in several places. Brian will look into this to remove this problem as he makes the second cathode board to complete the cathode sandwich. - The cathode is quite floppy and DSC is worried about vibrations from sources in the hall being transmitted to the cathodes. Tim has indicated that the only way that this could happen is if the resonant frequency matched the driving frequency. However, we still want some assurances that vibrations will not be an issue in our current design. Tim will do some calculations and Brian will follow up with him. Tim has also indicated that he has a list of all of the broadcast frequencies in the hall (pumps, etc.). We need to compute the natural frequency of our cathode design and then develop a simple mechanical test. - Brian will work on several things as he constructs the second cathode for the sandwich. One is to include a support ring for stiffness that goes between the 2 mm thick foam cathode backing and the ground plane. This is not part of the nominal design, but will be studies. Also he will attempt to seal the exposed Rohacell on the cathode backing with a thin layer of Kapton. This is something that we believe to keep the contaminants in the chamber volume contained.
Cathode Board Issues
- Roger has agreed to take on the following responsibilities:
- Contact flex board material supplier and flex board manufacturer to converge on the following issues:
- flatness specifications - elimination of cathode surface defects - handling procedures and requirements - transport requirements for boards - pre-made holes in cathode boards - QA plans and board checkout requirements at board house - minimum copper thickness (we would love to get our hands on boards with 0.5 micron and 1 micron copper for testing)
- Develop QA and board checkout document for the cathode flex boards upon delivery.
- Take care of all cathode flex board QA and board checkout for certification before cathode construction.
- Develop QA and board checkout document for the cathode daughter boards upon delivery.
- Take care of all cathode daughter board QA and board checkout for certification before installation in prototype.
- Arrange for cathode daughter board stuffing at JLab (talk to Kim as she is arranging this for the wire plane circuit boards). Develop stuffing and cleaning procedures document (consult with Fernando who is preparing a similar document for the wire plane circuit boards).
- Finalize cathode ground pour definitions and design to avoid anycathode current loops for protection from eddy currents induced with solenoid magnet quench.
- Finalize plans for connecting external ground to cathode boards (consult with Fernando who is developing a plan for the wire plane and ground plane connections).
- Take the lead in the procurement of the cathode boards and the cathode daughter boards
- Act as the contact for the cathode daughter board stuffing.
Gas Volume Definition
- Bill has completed a parasolid model that he will give to Dave Meekins to complete the flow/pressure calculations. We need to decide soon what the holes in the cathodes need to be. We are already planning for the inclusion of a beam hole in the cathode. However, there is also space available between the last cathode strip on either side of the board and the edge of the G10 support skim. Do we need to have these opened up? - Bill has worked with a local company to do some test laser cutting through a cathode board sample. After adjustment of the laser power, clean and precise cuts were possible. Roger will interact with the cathode board manufacturer to see what they can do. If this also a laser cutting procedure, we can just have them do the work to reduce handling of these fragile boards.
STB/HVTB Issues
- DSC, Fernando, Kim, and Roger will be meeting with Greg Arnold from the accelerator to discuss the needs and plans for stuffing of the wire frame circuit boards. Greg's group is available for this work. This meeting will be on Monday next week and we will also get a chance to look at their facilities.
Cooling System Update
- Bill has devised a test set up for study/testing of the preamplifier board cooling system. Denny is putting this together in his spare time. He has been working in Hall B and will be back with us next week.
Small-Scale Prototype
- Brian has been delayed in assembling the +/- 75 deg cathode boards. He has the boards and support frames in hand, and will get to this mounting shortly.
FDC Mini-Review
- The committee report from the mini-review has not yet been delivered. As soon as it appears, it will be circulated to everyone for review.
Cathode Daughter Boards
- Roger has nearly finalized the cathode daughter board design and he has now included the ERNI connectors. We still need to finalize how to get the external ground to the boards. Roger is also working with Chuck to ensure that there are no clearance/positioning issues with his cathode daughter board design.
Cathode Flatness Measurements
- Bill has been in contact with the machine shop. In addition to the horizontal mill machine, they also have a coordinate measurement machine that might be more appropriate for our needs. We discussed the problems with the laser measurement system that Bill found and have to overcome the hurdle of how to read this out or how to coordinate the CMM output with the laser position. Brian will explore getting a software person from his side. Perhaps also Elliot could be of assistance here. Bill will continue to gather information so that we can converge on a solution.
Meeting on LV/HV System Design
- The next meeting with Joe, Fernando, and DSC on the layout and design of the LV and HV systems for the tracking chambers will take place on Monday. We are working with Joe to finalize the system design. Over the last two weeks we have made the decision to reduce the number of LV cables in the system by a factor of two. The ERNI connectors were ultimately felt by Fernando to have too much redundancy. This redundancy can be reduced to feed more preamplifier cards with a single power line.
FDC Insertion Planning
- We discussed in general terms the issues with the installation of the FDC from the upstream end. We need someone to concentrate on all of the associated issues with this plan. What is the clearance needed for the FDC cables outside of the CDC? How will the cables be managed and strung so that the FDC can be inserted and extracted without touching the cables (and without destroying the detector)? What will the shell about the CDC look like? Joe Beaufait's name came up as a natural for this work. We need to find out if he is available to take on this work in a serious manner.
Upcoming Reviews
- The combined tracking/PID review for Hall D is scheduled to take place on March 27 and 28. At this point, we are converging on a charge and the list of speakers. We have to prepare talks and backup materials for the FDC, CDC, and charged particle PID systems. The details will be worked out over the next week or so and preparations will continue from now until the review. - In preparation for the meeting, we will need an updated set of design drawings for the FDC web site. New drawings from the mechanical model will need to be provided that reflect the current design.
Drawings
- DSC has collected all of the available FDC subsystem design drawings and placed them on the FDC website. The URL is: http://www.jlab.org/Hall-D/detector/fdc/drawings.html. Folks should go through the drawings and let DSC know what drawings and/or categories are missing for a complete design set. - Also folks should send DSC the lastest design drawings where there have been changes to keep this web site up-to-date through the review season.
Work List
- 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.