FDC Weekly Meeting
Date: March 6, 2008
Participants: Daniel, Simon, Brian, Kim, Chuck, Roger, Fernando, Bill
Next Meeting: March 13, 2008 @ 1:30 p.m.
- 1 Test Frame Wire Winding
- 2 Full-Scale Prototype
- 3 Composite Cathode Updates
- 4 Grounding Issues
- 5 Gas Volume Definition
- 6 Cathode Board Discussion
- 7 STB/HVTB Discussion
- 8 Dry Air Flow
- 9 Small-Scale Prototype
- 10 Cathode Flatness Measurements
- 11 LV/HV System Design
- 12 FDC Insertion Planning
- 13 FDC Mini-Review
- 14 Gas System Design
- 15 Upcoming Reviews
- 16 Drawings
- 17 Work List
Test Frame Wire Winding
- After some back and forth with the procurement folks at JLab and at Indiana, we have a version of the contract that Elke has given approval for signature. As soon as we have a signed contract, word will be circulated. - DSC has sent the wire frame design drawings to Keith Solberg at IUCF. They want to prepare a support structure for the wire frames that can be used during the wire attachment phase and also get the wire position measurement system up and running before Brian heads to Indiana. It is not fully clear when this will be, but the earliest would be in about 2 weeks. - Brian has prepared a slide with two samples of our sense wire (20 micron diameter gold-plated tungsten) and two samples of our field wire (80 micron diameter gold-plated copper-beryllium) to be studied in the electron microscope (belonging to W&M). Jose Riso, a Hall B engineer, will be handling this work. He will reported back to us on the wire quality and surface finish. - Brian should be in contact with Karen Kephart at FNAL regarding a procedure for the wire deadening (the electroplating process). This procedure should be attempted with our prototyped here at JLab in the first part of this year to finalize the procedures involved. - Brian will photograph completely all phases of the different aspects of the wire winding and wire deadening studies.
- Procurement for the full-scale prototype continues in earnest. The PR for the wire frame boards has now been signed and the boards should be delivered by March 27 (5 sets of boards). - The PR for the G10 has been prepared and the order is out for quotes. - The Rohacell order has been signed and has gone out. - The cathode boards and cathode daughter boards should be going out for quotes in about 1 week of time. The cathode board design is waiting for Chuck to weigh in on where the 10th cathode daughter board can go (this is for the ground connection). - Brian will put together an order for a second construction table (granite surface plate and aluminum construction jig) once it is clear that we will have a place to put it. DSC has already made a specific request to Dennis Skopik for temporary space in the clean room for this second station. The other station should be going into the clean room tent at some point for the prototype construction phase. - Bill will put together a PR for two rails and the rail attachment assemblies that he has designed. - Some known delivery time lines: Wire frame boards by March 27, 50-pin connectors for wire frames this week, 50-pin connectors for preamp daughter boards by July, ERNI connectors by the end of May, HV capacitors by May 9.
Composite Cathode Updates
- No further progress has been made on completing the construction of the full cathode prototype sandwich (cathode-ground plane -cathode). Brian will get back to this at some point soon. - There are several other studies that need to be finalized with this cathode sandwich. One is to finalize the gas port attachment scheme. Another is to come to some conclusion on the vibration studies. The vibration studies will only commence after we exhaust the possibilities of getting a calculation of the natural cathode frequency done in house. Chuck has been in contact with Ed Daly from accelerator about doing some calculations, but no committments have been made. - Another thing that Brian will study is to seal the back side of the exposed Rohacell. This piece is the 2-mm thick cathode backing structure. He will laminate on a thin Kapton sealant layer (thickness to be determined, but less than 1-mil). - Brian is currently organizing a stretching test of our full-scale cathode boards. Due to the very tight tolerances on the cathodes, stretching or distortion of thes boards during the construction procedure could be quite problematic. We do not expect that Kapton will be able to stretch too much, but this needs to be quantified. Brian will do a measurement using the CMM in the JLab machine shop. He will measure the length of a bare piece of the board material, and then he will wet it down to a surface plate, roll out the wrinkles, and measure the length of the board again. Any effects due to stretching will then be discussed as to their impact on the design. If the stretching is negligible, then we can request that the cathode board holes be pre-made by the board house. - Roger will get a piece of scrap cathode boards to do some soldering tests with the rigid flex cable.
- Fernando will supply an overall grounding specification document by next week (probably). - Fernando was given a piece of our ground plane material of size 1m x 2m to measure the surface resistivity of this material. - Kim has distributed samples of the male and female versions of the faston connectors that we are nominally planning on using to make the ground connections to the wire frame boards, the cathode boards, and the ground planes.
Gas Volume Definition
- Bill has provided Dave Meekins with our parasolid model to study the gas flow. Dave has gotten started on the calculations. The first model that he has includes the central beam hole in the cathodes, as well as a series of holes on both sides of the cathodes between the last cathode strip and the G10 frame. The goal of these studies is to finalize the layout of the cathode penetrations to allow for good flow through the chamber.
Cathode Board Discussion
- Before we can submit the cathodes for manufacture, we need to finalize our discussions with both the board material supplier and the board house regarding our flatness and handling specifications. DSC has drafted a document and has circulated for feedback. We need to complete this document this week so that Brian can pass it on. - We are still trying to find a supplier of the cathode board material with thinner copper. We are pursuing a number of leads, but nothing positive yet. Fernando and Roger are doing the leg work on this front. - Roger will prepare the QA/stuffing/cleaning documents for the cathodes and cathode daughter boards referencing the global document that Fernando has already posted (GlueX-doc-991).
- The PR has been signed and the board order is out with San Francisco circuits. Kim will prepare a document on board QA/stuffing/cleaning for Greg Arnold. - We finalized the plans for the first phase of board stuffing. - Kim has passed onto Brian the details for the needed modifications to the aluminum tooling plate jig for wire frame construction. This work is needed for the jig plate to clear the pre-stuffed components on the circuit boards. The work will be completed within the next month.
Dry Air Flow
- Chuck is responsible for sketching out the design of this system. The nominal plan is to add duct work from the CDC electronics cooling system and flood the solenoid with this flow. This is for local environment control for the FDCs.
- Problems came up with the soldering of the connectors to the cathode boards. Both boards have been mounted to their G10 frames. Bill Gunning is doing the soldering. With conventional soldering, the 2-micron copper strips cannot take the 700 deg heat from the iron. Brian is acquiring some low-temperature solder to attach the connectors. If this does not work well, we will pursue the attachment using conducting epoxy.
Cathode Flatness Measurements
- Bill is pursuing getting our cathodes measured for flatness at a company in North Carolina (Hexagon Metrology). If this does not pan out, he will move to procure a measurement system that we can install at JLab (a fairly inexpensive system that can be mounted on the CMM or horizontal mill in the JLab machine shop).
LV/HV System Design
- Fernando has updated the design documents (covering both the FDC and CDC). See GlueX-doc-966 and GlueX-doc-967. We are nominally planning on using a CAEN HV system and a Wiener LV system.
FDC Insertion Planning
- We had a planning meeting discussing detector installation and cabling, focussing on the detectors that go into the solenoid. We made a number of initial decisions for the design to proceed. These decisions were 1). The FDC is installed from upstream, 2). The cables from the FDC will exit the BCAL from the upstream end, 3). The FDC will be made capable so that it is removed from the downstream end of the solenoid for repair, 4). The CDC and FDC will not be hard coupled mechanically in any way. We also discussed an initial design direction for the FDC cable system and how the cables are locked into rails on the inside face of the BCAL. - Note that there is nominally 45 mm between the outside shell of the CDC and the inside face of the BCAL.
- The final report of the FDC mini-review has been made available to all. The bottom line is that they endorsed our nominal design as the better approach compared to a wires-only design.
Gas System Design
- Brian will work to complete a design of the gas system for the tracking chambers on the May time scale.
- The combined tracking/PID review for Hall D is scheduled to take place on March 27 and 28. At this point, we have converged on a charge and the list of speakers. The talks are being prepared and dry-runs are scheduled for next week. Completed details are given on the Hall D web site (http://www.jlab.org/Hall-D/guest_secure). - In preparation for the meeting, we will need an updated set of design drawings for the FDC web site. New drawings from the mechanical model will need to be provided that reflect the current design. - A new version of the FDC TDR has been posted on the portal (GlueX-doc-754-v5). Folks should look over the sections that are relevant to their work and provide feedback to DSC. This is the critical pre-brief document for the upcoming
- 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.