Difference between revisions of "Minutes-5-1-2008"
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- The final report of the committee that reviewed the Hall D PID | - The final report of the committee that reviewed the Hall D PID | ||
system and chambers was circulated. The marks for the reviewed | system and chambers was circulated. The marks for the reviewed | ||
− | systems | + | systems were high. |
==Drawings== | ==Drawings== |
Latest revision as of 20:25, 15 May 2008
FDC Weekly Meeting
Date: May 1, 2008
Participants: Daniel, Simon, Fernando, Roger, Kim, Bill
Next Meeting: May 15, 2008 @ 1:30 p.m.
Contents
- 1 Cathode Planning
- 2 Full-Scale Prototype
- 3 Test Frame Wire Winding
- 4 Stack Assembly Procedures
- 5 Composite Cathode Updates
- 6 Grounding Issues
- 7 Cooling System Tests
- 8 Gas System Design
- 9 Gas Volume Definition
- 10 STB/HVTB Discussion
- 11 Cathode Board Discussion
- 12 Small-Scale Prototype
- 13 PID/Chamber Review
- 14 Drawings
- 15 Work List
Cathode Planning
- Roger is working to complete the cathode board PR in the next several days. The goal is to have this on Elke's desk before the start of next week's systems review (which starts on Wednesday). - Roger has prepared a draft of some language for the PR that includes material handling language, electrical testing requirements (prepared by Fernando), and information on packing and shipping. On the shipping front, we were not sure if it was best to ship the cathodes flat or to have them rolled on a cylinder. Roger will talk to the Allflex company's sales representative for information. - As we are still not fully sure of the performance of the 2 micron Cu boards, we are still considering 5 micron Cu boards as an option (if we can make the boards without the 2-mm Rohacell backing, then the thickness is about the same). We thought that our best course would be to order boards with both 2 micron and 5 micron Cu. DSC talked to Elke about this, and she thinks this is a sensible approach. She wanted to better understand the costs. Roger is talking to the Allflex folks about prices and we will know more early next week. - No progress has been made during the past week on additional solder tests of the rigid-flex assembly to the cathode board mock up. Greg Arnold's group will begin this work after the solder pencil that they order arrives. This should be shortly. - Note that due to the height of the solder connection between the cathode board and the rigid flex assembly, we will have to revisit the design from the standpoint of adding clearance pockets on the surfaces that mate up against this solder region. This discussion will begin when Brian is available.
Full-Scale Prototype
- Outstanding procurements for the full-scale prototype: * The HV capacitors will be delivered to us in about 1 month. * The 2nd construction station PR has not been started. Brian will get to this when he is available. * The rails will actually not be delivered until mid-May. * The rail attachment assemblies are not ready for FSU to work on until Bill has time to complete the relevant drawings. * We are still awaiting delivery of the 2-mm Rohacell for the cathode backing. - DSC talked to Jack Segal during the week about our occupancy date for the EEL clean room tent. If all goes according to plan (and negotiations are still ongoing), we will be able to take over the tent in about 2 weeks. - Simon talked to Casey in the JLab machine shop about the modifications of the aluminum tooling plate used for the wire frame construction. Before he begins, he will need Brian to provide a detailed drawing. This still needs to be done. DSC will get Brian on this when he gets back to town. - Brian will begin wire frame construction for the full-scale prototype in earnest during the week of May 4. He expects the frame construction to take 3 days/plane. We will most likely prepare 4 wire planes for the prototype. - The keys to CC F117 are alledgedly available for folks to pick up. However, they are locked in the Forestry Building and we need to find someone who can let us in. More to come.
Test Frame Wire Winding
- The Phase 1 wire winding contract ended officially on Friday May 2. DSC has received a preliminary report on the status of the work, and this report will be improved by IUCF and updated over the next week. Basically they gave us what they had to fulfill the contract requirements, but it is not complete. - IUCF ended up winding 3 planes. Brian brought back two of them with him to study the transport scheme (looks like no wires broke on the 12 hour ride from Bloomington to NN). There were some problems that were found during the winding process: * The technique used to support the wire frames under the wires was non-ideal and this cause significant problems with the final wire placement on the boards. This problem was diagnosed after winding the first two wire planes. A modified procedure was used on the third plane with improved results. * The placement on of the field wires on the winding table, done after the sense wires were wound, had a minor problem. The technician did not account for the differences in wire size. Thus the wire spacing had an offset (too big on one side of the sense wire, too small on the other). This is not a real problem, and will be accounted for in future winding. * The wire placement distribution shows a fairly sizeable number of wires outside the +/-50 micron spec. The fraction of these outliers is about 10%. This is more than an order of magnitude too large. The folks at IUCF are investigating this, but believe that it may be caused by worn equipment on their wire spooling and winding equipment. * There was suspicion that the wire measurements had a correlation of where on the measuring machine the wire frame was placed. Data were taken to quantify this problem, but DSC has not gotten the analysis as of yet. * The wire tension measuring system was painfully slow, and so full tensions measurements on all wires were not completed. Kim provided the IUCF folks with the wire lengths, and they have taken hopefully sufficient tension measurement data to give us a feeling of what tolerance they can provide. We had requested +/-5%, but it may be that +/-10% is what their system can provide. We will know more shortly. * DSC will go over the Phase 1 data and meet with Elke to plan on when and if Phase 2 will take place. We need to be sure that IUCF can meet our specifications, both in terms of the detector requirements and the budget. * Finally, much thanks to Brian who spent a long week at IUCF representing our group. - DSC is working with Steve Christo to prepare a wire specification document for the tungsten and CuBe wires leading up to procurement. Steve is preparing a document for the Hall B chambers and we will most likely adopt this document for Hall D. DSC reviewed the existing Hall B documents to give folks a flavor of how these documents have been prepared in the past. We need to make decisions on what is required for the FDCs.
Stack Assembly Procedures
- DSC, Brian, Tim, 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.
Composite Cathode Updates
- Denny has extracted the tensioning system from mothballs and it is now being setup in the shop. Brian will work to make a tensioned cathode without foam backing on his return. In tensioning the cathode plane he will study how the 3 piece cathode reacts under tension. He will also measure the electrode distortion as the tension is increased. Note that after the meeting, there was some confusion on what was happening in the machine shop. Casey thought that he was supposed to do the tensioning exercise. There were clearly no plans in place for doing the measurements of the cathodes and Brian did not talk to Denny before he left town. DSC therefore put a hold on this work until Brian gets back. We do not want things done without a clear plan and communication is important. - Denny has the Acquity Laser system from Fernando and has it fully set up trailer 94B. He has done some test measurements and verified that the measurement results agree with crude measurements. DSC told Bill to go ahead and purchase the system from Acquity. After the test measurements, Denny started measurements on the two prototype cathode planes. Measurements will be available early next week.
Grounding Issues
- Fernando completed preparations of an overall Hall D grounding specification document (GlueX-doc-1021). He incorporated the comments that he received from the collaboration and posted a new version on the portal.
Cooling System Tests
- Denny completed the set up of the cooling system. He then packed it up and will move it to F117 after the system review. Fernando will take over the measurements and study the cooling properties with a fully loaded preamp daughter board in place.
Gas System Design
- Vladislav (Slava) Razmyslovich is working on a preliminary layout of the gas handling system for the CDC and FDC in preparation for the upcoming systems review. We will sit down with him in a specialized meeting to review the design concepts after the review is over.
Gas Volume Definition
- No progress on new calculations during the past week. We will revisit the issue of modeling the gas in the drift cell region if the input is in the wire frame or spacer after the systems review.
STB/HVTB Discussion
- Kim has updated the wire frame PCBs to widen the STBs and HVTBs by 3 mm to beef up the overlap region. We will not work more on these boards until after study of the existing boards on the full-scale prototype. We can revisit the design of the overlap region again before production submission. - Kim needs to provide an instructional writeup for the Phase 1 and Phase 2 wire frame PCB component attachment. This is on her to-do list, but is not a high priority for now.
Cathode Board Discussion
- 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.
Small-Scale Prototype
- Work continues on characterizing the preamp daughter boards to specify the ASIC dynamic range for both the FDC cathodes and wires. Simon is extracting from the data the amplitude distributions. He should be close to completing this analysis of the data. He will circulate it for discussion. He will also circulate plots of the charge collected as a function of the readout time. - Simon, Fernando, and DSC will prepare a write-up of the analysis results and our analysis of the required dynamic range of the anodes and cathodes. Fernando will be in contact with Mitch Newcomer on our progress and plans. Our goal is to have a first draft of a report on this work by the end of next week. After the systems review, we will spend a few days to polish up the report and circulate it to a wider group for comments before passing the information on to Mitch.
PID/Chamber Review
- The final report of the committee that reviewed the Hall D PID system and chambers was circulated. The marks for the reviewed systems were high.
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 latest 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.