FDC Weekly Meeting
Date: April 24, 2008
Participants: Daniel, Simon, Fernando, Roger, Mark, Kim
Next Meeting: May 1, 2008 @ 1:30 p.m.
- 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 Drawings
- 14 Work List
- Roger heard back from the representative at Allflex. They have said that they can have our board material in house from Nippon Steel Chemical Co. by the end of May and deliver the boards to us within two weeks after this. Roger will work to complete the PR in the next few days. - Roger still needs to discuss with Allflex our electrical test/QA requirements. He needs a statement from Fernando. This will be built into the PR. - Roger still needs to discuss with Allflex our surface defect specifications and needs to prepare details on how the boards needs to be handled and prepared for shipping. He should start with the specs for the wire frame circuit boards that Kim used and they should be reviewed. This will be built into the PR. - The draft PR with all of the above issues and specifications included will be circulated internally for comment and feedback before this PR is signed and submitted. - 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.
- 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. - We had a meeting with Dennis Skopik on the clean room availability for the full-scale prototype construction. We expect that the negotiations are nearly complete and we should expect occupancy in the EEL building clean room (in the clean tent) in about 2 or 3 weeks. More to come once plans are finalized. - Brian talked to Casey in the machine shop about completing the modifications on our aluminum tooling plate for the wire frame construction. Casey thought it best to do this until just before construction. DSC has suggested that this work is completed first thing after Brian returns from IUCF (April 28-30) so that it is ready after Brian gets back to JLab from vacation on May 6. - 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.
Test Frame Wire Winding
- A phone conference with IUCF took place just after the meeting. Both wire planes are wound. The tension and wire placement measurements have begun. * The tension measurement is going very slowly due to the technique employed. Everyone is convinced that the results are reproducible. Preliminary analysis shows (for the wires measured) that the tension is stable to +/-10%. This seems to be reasonably under control. IUCF will complete the tension measurements for portions of only 1 of the planes today. * There are some issues with the wire placement measurements. Sizeable deviations from the nominal placement position have been seen in the measurements. IUCF claims that several effects may be responsible. One is that the wires were laid on the table with specifications but that there could be a problem with the measurements. We mapped out a strategy to test this theory by measuring the same plane in the same position but at different positions along the measurement system. A second theory is that the problems occurred due problems getting the wire plane to the correct vertical height under the wires before soldering. The third theory is that the wires were not laid down on the table accurately due to problems with the spooling system. ** IUCF will test the first theory day (about the problems with the measurements). They will wind the third frame that Brian brought after modifying the frame support to put the frame at the correct height relative to the wires. ** The last theory about the problems with laying the wires on the table is a bit trickier and we may not be able to solve in the short term. * Brian will be heading back to JLab tomorrow. He will bring back the wound frame with the low-density Rohacell core. This will enable us to test our proposed transport method. - IUCF is having a meeting tomorrow to go over the Phase 1 budget situation and how much money they have spent. The Phase 1 contract runs out on May 2. If they require a no-cost extension, then this can be done very easily. If they are not able to demonstrate that they can meet our specs and have run out of money, then we will need to discuss this internally. DSC transmit all of these points clearly to IUCF. - 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 setup in the shop. Brian will work to make a tensioned cathode without foam backing on his return from IUCF. 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. - Denny has the Acquity Laser system from Fernando and has it nearly fully set up trailer 94B. The sensor is attached on a precision vertical pole with its position controlled by a stepper motor. He has downloaded all of the GUI software from Acquity and has gotten it all working. He will pick up the two prototype cathodes and bring them out to the trailer. He has designed and constructed a support frame for the cathodes and will make final adjustments to it once he has the planes. In short, he is essentially ready to begin the flatness/bulge measurements. Results will be posted once they are available.
- Fernando has completed preparations of an overall Hall D grounding specification document (GlueX-doc-1021). This is needed for pre-brief material for the upcoming Systems Review on May 7. Please read it over and provide feedback to Fernando soon.
Cooling System Tests
- Denny has nearly completed the set up of the cooling system. He still has to include the thermistors for reading out the coolant temperature local to the preamplifier board. DSC has received the attachment brackets from Bill and passed them on to Fernando. Fernando will take care of the measurements. The tests will take place in F117. The cooling system will be moved over there once we have gotten the keys to this room (the order has been placed).
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.
- Last week we discussed the overlap design of the neighboring wire frame PCBs. It was agreed that this overlap is a critical part of the design and must be kept. - We reviewed the weak areas of the boards. DSC asked Kim to modify the ends of the STBs and HVTBS to add 3 mm of 1/32-in material to the ends before the overlap region to improve the strength. Kim did not think that this would improve things too much, but the corners of these boards have no 1/32-in material in contact with the portion removed for the lap joint. This leads to fragility and pealing of the boards. Kim will make the minor modifications to the STBs and HVTBs, as well as the corresponding adjustments to the filler boards. She has already checked with the board house on width, and we can add the few mm of width without any problems. - 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. - Roger was planning to do some test soldering for the rigid flex cables to a sample cathode board. No update was given during the meeting.
- Simon has gotten the readout of the cathodes working with the ASICs/shapers/FADCs. Some same pulses have been placed in the FDC elog. - Simon is now extracting from the data the amplitude distributions for the anodes and cathodes. 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.
- 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.
- 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.