Minutes 12-13-2007
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FDC Weekly Meeting
Date: December 13, 2007
Participants: Daniel, Brian, Simon, Roger, Kim, Chuck, Fernando, Bill, Mark
(Curtis, Yves, Gerard for FDC/CDC portion)
Next Meeting: December 20, 2007
Contents
Manpower Update
- DSC has talked to everyone matrixed into the FDC effort regarding work plans and time lines. The time lines that have been established will be revisited in January 2008 and modified to take into account the delays in the project.
Composite Wire Frames
- Brian has completed construction of 5 composite wire frames. Two low density Rohacell core frames and one medium density Rohacell core frame will be selected for the phase 1 winding project. - Brian has indicated that he is satisfied that he has developed a construction procedure that will be amenable to mass production of these frames. The alignment jig worked quite well and Brian has setting on employing Hysol epoxy for the construction. - The next step in the process is to deliver the frames to the JLab machine shop to add the o-ring grove on the back side and to add the through holes. This work will begin in January and take about two weeks to complete. - The storage/transport container that should have arrived at JLab last week has not yet shown up. Brian will look into this and make some calls.
Wire Stringing
- Work continues from the folks at IUCF to finalize a statement of work and budget that they are happy with. The first version of the SOW that they provided to me include language for Phase 1 only. I have asked them to modify this to include all three phases. Also the administrators have not fully accepted the budget that was prepared for the 3 work phases by the head of the wire chamber lab. They want to increase the contingency estimates as they are nervous about the current contingency levels (that DSC thought were quite reasonable). The bottom line is that we don't quite know what to expect for a budget from IUCF. However, it looks like we should receive it before the end of the year. At that point the JLab procurement folks will take over. They indicate that if things go smoothly, we should have a signed contract from both parties before the end of January 2008.
Composite Spacer
- Yesterday we found out that Kim had not received the information on the spacer ring that goes between the face of the wire plane and the neighboring cathode frame. Because she did not have this information, she had started to put components in the space occupied by the spacer ring. - The current design of the spacer ring is a composite annulus of I.D. 1022 mm and an O.D. of 1060 mm. The I.D. is set to clear the solder pads and the O.D. is set to go just beyond the through holes. Tim will look into whether we can slightly decrease the O.D. or add cut-outs (scallops) between the through holes to give Kim more room to layout the STB boards. Here real estate is a major issue in the space immediately between the daughter board connector and the outer edge of the spacer ring. - The spacer design includes an o-ring groove on each side to give a gas seal. In the current design, these o-ring grooves lie directly on top of each other. The depth of the groove goes through the G10 skin and into the Rohacell backing. These rings will require special handling to be sure they don't fall apart. However, he was fully convinced that they are structurally sound to handle the compression and to provide the light-weight spacer that is required.
O-ring Material
- We had a discussion on the choice of o-ring material. The two options are Viton or a silicone-based material. DSC is worried about the use of any silicone-based material that can come in contact with the chamber gas volume. This stuff is definitely chamber-unfriendly. - One of the biases toward silicon-based o-rings is that they are believe to be softer than other materials. Thus less force would be required to give a good gas seal. However, during the discussion it became apparent that the Viton o-rings come in different types, some of which are quite soft and should do the job for the FDC.
STB/HVTB Design
- Kim had a bit of a set back with the issue of the space required for the spacer (see above). This is a relatively minor issue for the HVTB boards, but is still an issue on the STBs. Is there enough real estate to lay out the traces and the required components. - The plan for wire frame stuffing is to do as much of this as possible before the wire winding. This is viewed as important to minimize handling of the wound frames. Also, the large-scale stuffing will have to be done by an outside company, and it makes no sense to send out frames with wires on them. This is asking for trouble. After the winding is complete, there will be a few remaining components to solder onto the boards, and that will be here at JLab. - Kim has nearly completed the design of the HVTB boards. She has a few issues with some resistors not being placed between the solder pads. There are some other relatively minor technical changes requested by DSC and Fernando, but these boards are converging nicely. - It was agreed by all that the positions of the daughter board connectors on the STBs can be viewed as final. Kim can now start the detailed work of laying out the traces from the HV-blocking caps to the daughter board connectors. The power and ground layout has been extensively discussed and we are converging on a good design in this regard. - As the circuit boards will not be done this year, we will seek to continue having Kim work on these boards at the 50% level for January 2008. This will allow her time to complete this work and oversee the procurement of the boards for the prototype.
Cathode Boards
- The positions of the daughter board connectors are not yet final on the cathodes. They were recently repositioned to be compatible with the cooling system developed by Bill. However, he forgot to take into consideration the fact that the cathode board is a three-piece design. Bill and Chuck will look into the problems and report back to the group on the issues and what can be done about them.
Upcoming Work
- Brian will start work next week on the construction of our first composite cathode sandwich. So far, only sandwiches made with solid G10 rings have been attempted. - Brian will mount the +/-75 deg cathodes for the small-scale FDC prototype on the associated frames in the first part of January. - Simon will give an update next week on his analysis of the B-field test data to let us know where we stand and what is left to do. - We discussed the offer of additional help for the FDC system from the accelerator group and could not come up with anything at the current time.
Drawings
- The folks responsible for the individual design aspects for the FDC should provide a complete set of design drawings (even if they are preliminary to DSC). We need to understand where we are at in the design and what areas we have not covered.
Cathode Board Readout
- Roger has completed his design plans for the scheme to connect the cathodes to the daughter board connectors. The solution is a simple circuit board that the daughter board connector is mounted to. This circuit board includes a few resistors for addressing the daughter board card. The flex cable will attach to this board and be soldered to the cathode. The circuit board that Roger has designed will attach to the back of the G10 skin that supports the cathode. - At the present time, he has submitted his circuit board design for quotation. He expects to complete procurement before the end of the year. The plan is to put together a mechanical prototype of this connection scheme to see how and if it will work for the FDC.
Other Updates
- The next FDC Monte Carlo meeting will take place tomorrow. Progress reports will be made on the continuing development of the track finding and fitting algorithms and the issues with modeling the chamber response in the magnetic field.
Combined FDC/CDC Discussion
- We discussed the current status of the ASIC/daughter board tests that are ongoing at CMU. So far the output of the amplifier board is totally dominated by noise. The CMU folks are working on this to track down the source/s. The FDC group will install their daughter boards on the small-scale prototype early next week if all goes according to plan. As it is crucial to get this all working, Fernando and Gerard will be very hands on, both at JLab with the FDC and at CMU with the CDC. Mitch will need our feedback on the ASICS by no later than March 1, 2008. Fernando will circulate a document on what tests need to be performed for feedback to Mitch. This document will be circulated in the next few days. Note that at the current time, Mitch is working to understand why the measured power dissipation of the ASICS is larger than what he had simulated. - Curtis indicated that we will need to complete another version of the Hall D design report in time for the March chamber review. - We reviewed the plans for the FDC cooling system designed by Bill. CMU would like to employ a forced-air cooling system. Bill and Fernando will be doing some thermal tests with the daughter boards to give feedback to this plan as well as the FDC cooling design load. - We discussed briefly the plans for the LV and HV systems and the associated grounding requirements. Fernando is thinking about this at the current time. DSC will be meeting with Joe Beaufait soon to start work on the design of these systems. - We discussed chamber installation and alignment systems briefly. Neither the FDC nor CDC folks have thought too hard on the details and specifics of either topic. However, both groups do have some documented descriptions of how things should be installed and aligned in general. Over the next several months, we will work to flesh these ideas out. - We discussed monitoring and time histories. Both groups will first need to prepare a list of what they would like included in the monitoring and time histories. We can then approach the Hall D slow controls group (O.K., ..., Elliott) about our ideas.
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.