FDC Weekly Meeting
Date: Feb. 7, 2008
Participants: Daniel, David, Mark, Simon, Roger, Brian, Elke, Kim, Chuck, Fernando, Curtis, Yves, Paul, Matt, Bill, Tim, Elton, Gerard
Next Meeting: February 14, 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 Gas Volume Definition
- 10 FDC Construction Space Request
- 11 FDC Mini-Review
- 12 Meeting on ASICs
- 13 Full-Scale Prototype
- 14 Drawings
- 15 Work List
- 16 Combined FDC/CDC Meeting
Test Frame and Prototype Wire Winding
- The purchase request for the Phase 1 and 2 wire winding has been signed by Allison Lung and passed onto the procurement folks at JLab and IUCF. The IU procurement office is reviewing the documents and providing a final budget. We expect that a signed contract for the wire winding will be in hand within the next several weeks. - DSC will be in contact with the IUCF folks to finalize a list of equipment and supplies that we will need to bring with us. Brian will procure any items that we do not have. - Brian needs to check whether he can actually go to IUCF for the week of the test frame wire winding given his ISM responsibilities. DSC will follow up on this.
Full Scale Prototype
- DSC is working on a stripped down budget for what we want to construct. The full-scale prototype will most likely consist of half a package (U-V-W) only. Once the final budget is approved by Elke, we will begin procurement of the pieces required.
- 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.
Composite Cathode Discussion
- Brian and Denny have completed construction of two composite rings for the cathode sandwich. They have used the 1/32-in thick G10 skins and a 5-mm low density Rohacell core. They are now working on laying out the first cathode boards (3 pieces with the dummy cathode boards). This cathode sandwich should be completed by Monday or Tuesday next week. - A second prototype will be constructed using our current thinking for the attachment and layout of the ground plane. - Brian will prepare a construction procedure document with a full set of photographs as he constructs the last prototype cathode. - Bill circulated a specification document for measuring the cathode surface flatness. This document was discussed and feedback was given. Bill discussed a laser interferometry system that might be able to perform our flatness measurement for the cathodes when they are in a vertical position (and should work on the Kapton/copper surface). This system could mount to the horizontal milling machine in the JLab machine shop. This machine has a 40-in movement range. The system should provide accuracy to better than 50 microns. The cost for the sensor and software is on the order of $2k. We would need to develop a frame to support the cathode frame. Brian and Bill should work together to come up with a complete budget estimate for this system and the associated measurements. Brian and/or Bill should talk to the JLab shop about the availability of the milling machine for the work we want to do.
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.
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.
- One minor complication that came up is that Brian's assembly jig does not allow for components to be on the boards. He has a clear idea of how the alignment jig needs to be modified to handle the stuffed boards and will lay out a design for discussion. - We will most likely stuff the prototype chamber boards here at JLab. DSC and Fernando will meet with Kim and the folks in her building that do this work to go over what is needed. This meeting will take place next week. We need Fernando to prepare a writeup to detail the board stuffing and cleaning procedures. - 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 finalized the HVTB design and the design for one of the STB boards. By tomorrow she should have completed the layout of the second STB. Fernando will look this over and give final blessings. Kim is working to get quotes for all of the wire frame circuit boards.
- Brian will mount the +/-75 deg cathodes for the small-scale prototype next week. Simon plans on installing them shortly after thereafter for testing.
Gas Volume Definition
- We have not yet converged on the gas distribution to the FDC packages. We had originally intended to feed each layer within a package with its own input and output lines. However, the differential pressure across the cathodes that is planned would cause a significant outward bowing of these planes. We then began to consider making each FDC package a single gas volume. However, there are concerns with the impedance and the ability to flow gas through the volume quickly. - A new idea came up to keep each chamber layer an individual gas volume with the ground plane the barrier. The cathodes would still have holes in the middle and possibly the edges on either side after the last cathode strip. The gas input line for each package would then be distributed in a parallel fashion to each layer in the foam behind the cathodes. This design might also call for a slightly thicker ground plane to handle any unbalanced pressure load between neighboring layers. We need to prototype this and make a decision on what we are going to build here.
FDC Construction Space Request
- DSC prepared a space request document for the FDC construction that will be given to Elke tomorrow. This document was reviewed and minor changes were added.
- The FDC technology choice mini-review took place last Friday. The review committee strongly endorsed our current design with two crossed cathode strips imaging the wires. The final report from the committee will be provided in about one week.
Meeting on ASICs
- Fernando has set up a meeting with Mitch Newcomer and Gerard to discuss the current studies with the ASIC and the design plans. This meeting is scheduled for Wednesday Feb. 13 at 2:00 p.m..
- We are working to complete the design of the full-scale prototype so that construction can begin in the next month. What we actually construct is predicated on how much money is available in the budget. DSC believes that the ABSOLUTE minimum that should be constructed is a pair of neighboring layers (4 cathodes, 2 wire planes). The preferable minimum is half a package (6 cathodes, 3 wire planes). - DSC will prepare a budget for half a package for Elke to review to make a decision based on what is available in the Hall D budget.
- 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.
Combined FDC/CDC Meeting
- The first 45 minutes of this week's meeting was a combined FDC/CDC meeting to go over issues common to both groups. The main discussion was on preparations for the upcoming tracking and charged particle PID review in March. David is leading the effort on the Monte Carlo to connect the physics requirements to the detector design specs. Matt Bellis is also working on things more from the PID standpoint. One of the main arguments that will be made for the March review is to compare the FDC/CDC specs (position, angle, momentum resolution) to those for BNL E852. Our specs are very similar. If they were able to perform successful PWA analyses, then GlueX will also be able to at similar levels. - Curtis and Yves also discussed the current situation with the CDC prototype tests. They are presently awaiting delivery of 18-m long Spectra-strip cables for test the system. Another issue with the CDC is to develop the algorithms and codes to test the dE/dX resolution of this detector. One thing that is missing is the ability to distribute a universal clock to the FADCs so that straws from multiple FADC modules can be linked together for a given event. Kim will work on this clock distribution board based on input from Gerard and Fernando. - We discussed the idea of z-vertex resolution for the CDC. One idea that Curtis has proposed is to link together pairs of straws at the downstream end of the CDC (linking straws that have a low probability of firing from real tracks at the same time). This linking could then allow for a charge division measurement to fix the z-coordinate of the track with reasonable resolution. The development of these ideas will not happen before the March review. - We discussed the notion of routing the FDC cables out the upstream end of the solenoid. The FDC group needs to provide Curtis and Yves with the amount of radial real estate needed for the FDC cables and cable support structure requirements to decide how many outer layers to remove from the CDC (either 1 or 2 layers).
Minutes prepared by Daniel. Send any comments or corrections along.