FDC Weekly Meeting
Date: Feb. 14, 2008
Participants: Daniel, Mark, Simon, Brian, Kim, Chuck, Fernando, Bill
Next Meeting: February 21, 2008 @ 1:30 p.m.
- 1 Test Frame and Prototype Wire Winding
- 2 Full Scale Prototype
- 3 Cathode Boards
- 4 Composite Cathode Discussion
- 5 Gas Window/Frame Design
- 6 Cooling System Update
- 7 STB/HVTB Issues
- 8 Small-Scale Prototype
- 9 FDC Construction Space Request
- 10 FDC Mini-Review
- 11 Meeting on ASICs
- 12 Meeting on LV/HV System Design
- 13 Mechanical Prototype Proposal
- 14 FDC Insertion Planning
- 15 Upcoming Reviews
- 16 Drawings
- 17 Work List
Test Frame and Prototype Wire Winding
- IUCF is now reviewing the paperwork that we sent them on the Phase 1 and Phase 2 winding of the prototype planes. We expect to hear back from them this month. DSC has been contacted by the IUCF folks and expects that there will be some back and forth on the language before anything is signed. It seems clear that no winding will take place this month. An update will be given when more news is available. - DSC has contacted the IUCF folks about what supplies they want us to bring for the Phase 1 winding. This information will be passed on to Brian when it is available. - Brian has checked with Stan and the ISM team that he is serving on and has said that there will be no problems with him traveling to IUCF when the Phase 1 winding takes place. - DSC has asked Brian to check the sense and field wire quality. DSC has contacted Steve Christo from Hall B about the possibility of checking the wire under an electron microscope here at JLab.
Full Scale Prototype
- DSC has completed a stripped down budget estimate for a half package full-scale prototype. This information has been sent to Elke for review. When we hear back from her on the money available in the budget, we will iterate on our plans if necessary and then move immediately to begin the procurement phase for the prototype.
- Roger will take over all aspects of the cathode flex boards. He is already responsible for the design, but he should take care of paperwork, procurement, QA planning, etc. Roger should also work now to contact the cathode board material supplier and the circuit board company to get them to understand our flatness requirements. Why do the boards come to us with clear surface defects and can these be eliminated? We also need to work with these companies to specify board handling and transport. - Roger needs to find out what QA tests will be done by the board house to verify the quality of the boards (complete set of resistance checks would be a minimum). - Roger needs to find out from the board house whether we can have the cathodes delivered with the cut-outs already in place at the center and possibly the edges of the boards for gas flow. - Roger needs to be on contact with both the flex board material supplier and the board house on the minimum copper thickness that we can get on the cathodes. We sure would like the option of 0.5 micron or 1 micron thick copper strips (assuming that the 2 micron copper thick strips show no problems in the small-scale prototype). - Roger was away on vacation this week, but we still had a lengthy discussion on the ground pour layout on the cathode boards. We want to have as large a ground pour area as possible, and we also need to take care that we do not have a complete current loop for eddy currents in the case of a solenoid magnet quench. Roger is aware of these issues, but we need to have a separate meeting with him to finalize the cathode layout. - We discussed briefly the plans for connecting the ground between the three separate flex boards that make up one cathode board. The current idea is to rely on a thin layer of conducting epoxy, but this needs to be finalized and prototyped. - DSC would like Roger to prepare a document on QA for the cathode boards when they are returned from the board house. This document should be reviewed by Fernando.
Composite Cathode Discussion
- Brian and Denny continue work on the composite cathode sandwich prototype. Progress has been minimal in the past week as Brian has been out sick. At the current time, one cathode plane has been prepared from the three separate pieces of dummy flex board, and these have been epoxied to the composite ring. The 2-mm thick Rohacell backing has been glued into place. The next cathode board will be laid out tomorrow and finished on Tuesday of next week followed by attachment of the ground plane and the connection of the two cathode planes into a sandwich. We still need to finalize how we will connect the external ground to the ground planes and to prototype this design. - Brian will prepare a construction procedure document with a full set of photographs as he constructs the last prototype cathode. - Bill is responsible for preparing a document to lay out the costs associated with the laser interferometry flatness measuring system that he has identified. This document should also include a brief description of the measurement requirements and measurement plan. This will be discussed in the group and iterated on before being passed on to Elke for review. If the budget is reasonable, Elke will give the green light to begin procurement. Bill should also talk to Casy Apeldorn in the JLab machine shop about our plans and need for the horizontal milling machine. Of course, any expected charges from the machine shop should be included in the budget estimate.
Gas Window/Frame Design
- With the new idea of having each FDC package as a single gas volume, we need to design the gas windows and frames. Brian will come up with a design and circulate for comment. When the design is finalized, we can have Chuck put it into the CAD model. We still need to determine the thickness of the gas windows. - We again reviewed the new plans for the gas volume definition and Brian will plan on designing a gas port system for inclusion in the Rohacell of the cathode frame (between the cathode flex boards and the ground plane). - We would still like to model the gas flow with this new design. Some combination of Bill and Chuck need to develop a model to give to Dave Meekins to run his flow calculations on. We want to make sure that we have good flow and gas distribution through our active gas volume. This is also necessary to finalize what holes are needed in the cathode planes.
Cooling System Update
- Bill is working with Denny and Fernando to put together a test setup for the cooling system. This will include a water-based chiller borrowed from Hall A and a cooling loop with appropriate sized plumbing. Bill has already gotten several brackets that attach to the preamp that will clamp to the cooling loop. He has brackets made in copper and aluminum. The preamp card will be supplied by Fernando and is one of the version stuffed with 3 ASIC chips. The board will be outfitted with a thermocouple for temperature readback. The board will then be packed in some amount of insulation to mock up the real FDC environment inside the solenoid. - Bill will be in charge of the tests and will take all of the data relevant to be sure the cooling system can supply the required cooling power. He will also work to define the flow parameters of this water-based chilling system for the ultimate Fluorinert system that is planned. Bill will also document the test setup and take lots of pictures. - Due to lack of time, progress in this area was not discussed. We will bring it up at our next group meeting.
- We discussed the modifications needed in Brian's assembly jig for the circuit boards to clear the pre-stuffed components. The radius of the components will be different on the STBs and HVTBs. Kim will provide Brian with the clearance regions. Brian will also include some sort of alignment marks on the jig to ensure proper placement to avoid crushing the components. - We will stuff the prototype chamber boards here at JLab. DSC and Fernando will meet with Kim and Greg Arnold next week to discuss the plans and the issues. - Fernando will prepare a writeup to detail the board stuffing and cleaning procedures. This document should clearly delineate between the stage 1 board stuffing (pre-winding) and the stage 2 board stuffing (post-winding). It should also include clear handling instructions for the stage 2 winding to ensure that there are no possibilities of damaging the wire planes or breaking any wires. - Kim will prepare a QA manual for the wire frames to test them after we get them back from the board house. She will also be responsible for initial QA tests. - Kim has essentially completed the layout of the STBs and HVTBs (with one minor issue with the grounding on the HVTBs) and the board designs have been sent out for quotes. Kim has already received quotes from two sources for the board connectors and components. The prices are higher than anticipated due to the requirements of minimum order size. The components are very cheap, the issue is the connectors. One set of connectors that is required has a VERY long lead time of 3 months or more. Kim will move immediately to place this order. The rest we will decide on over the next several weeks. To keep costs low, we will probably use several different companies for the procurement of these parts to avoid the minimum order size issues as much as possible. - We discussed the issues of eddy current on the wire frame circuit boards in the case of a magnet quench. We have a design the presently does not have a complete loop, so we are satisfied here. The other issue that was discussed was the connection of the ground to the circuit boards. The ground will be connected via a spade-type connector that Fernando has identified. This same connector will be used on the cathodes as well. Ground will be distributed from circuit board to circuit board via the Erni-style connectors.
- Brian will mount the +/-75 deg cathodes for the small-scale prototype as soon as he is done with the composite cathode prototype. Hopefully (as I have been saying for several months), this will happen next week. We think that we have all the necessary parts gathered for this work. Simon plans on installing them shortly after thereafter for testing.
FDC Construction Space Request
- DSC prepared a space request document for the FDC construction that was given to Elke. She will pass this on to the facility management folks who will hopefully work with us to find the required space for construction.
- 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.
Meeting on ASICs
- We had a meeting with Mitch Newcomer and Gerard Visser on Feb. 13 to discuss the current studies and future designs plans for the ASICs. Mitch and his group still have a lot of design work to complete, although they have made progress in all areas and they know exactly what is left to be done and how long the work will take. - We have already made the decision to not submit the second version of our ASICS in April. The time is too short and we still have to much work to do. The next submission time is believed to be in June. - We need to clearly specify the gain requirements and dynamics range for the ASICS from both the CDC and FDC systems. It may be that the design that is required for the FDCs is not compatible with the design required by the CDC. The required tests for the CDC and FDC were discussed and clarified. - For the rest of this year, we will only have a total of 10 stuffed preamplifier daughter cards. The CDC folks only need 1 or perhaps 2 boards. The FDC folks would like 4 cathode boards and 1 anode board in order to fully outfit the small-scale prototype. We agreed that this will happen soon. Gerard has sufficient boards and parts for all of the needed shapers.
Meeting on LV/HV System Design
- Fernando and DSC met with Joe Beaufait this morning to continue our discussion on the design and layout of the FDC (and CDC) LV and HV systems. Joe was brought up to speed on the current design plans that have evolved slightly since our last meeting with Joe about 3 weeks ago. There was significant discussion on the number of cables that need to connect to the chambers and how much redundancy is needed in the system. We will converge on this and Joe will start preparing drawings. We will meet again within the next two weeks.
Mechanical Prototype Proposal
- DSC has prepared a request for funds and personnel for the construction of a mechanical prototype for the FDC. The proposal was briefly discussed and DSC forwarded the request to Elke after the meeting.
FDC Insertion Planning
- Bill discussed his idea for the rail system that the FDC will ride on inside the solenoid and his planned attachment scheme. This was met with favorable review. Bill still needs to decide on the size of the rails themselves. The rails that he is leaning towards are from Igus rail (the W series to be exact). - We need to define the required space for the FDC cable bundles that will reside outside the CDC. Chuck has already been looking into this, and has already been in discussion with Curtis. The CDC will be affected in that they will have to remove their outermost layer of straws. We need to have a final set of drawings and have a final group discussion on this issue before we get too far. - We need to have a discussion on the cable runs and plans for being able to install and extract the FDC system without having to disconnect the signal cables. Also during the insertion and extraction procedures, there can be no stresses applied to the preamp boards or cables. - Finally, we need to come up with a design for how we will bring the signal cables and power cables out of the solenoid. It appears that the gas and cooling lines could come out on the downstream side of the solenoid.
- 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.
- 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.
- 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.