FDC Weekly Meeting
Date: April 10, 2008
Participants: Daniel, Simon, Fernando, Roger, Bill, Mark, Jim
Next Meeting: April 17, 2008 @ 1:30 p.m.
- Fernando provided some contact information for several companies (Microconnex, Multek, Minco) over the weekend. Roger has initiated contact with representatives for each of these companies. It looks like Microconnex cannot handle boards anywhere near our size. Multek is a sister company of Sheldahl and they are interested in our project. They are looking to see what they have in stock and look more into their capabilities. They will contact Roger again shortly. Minco has not yet been contacted. In making these contacts, Roger was turned onto a company called Allflex that could possibly do our etching. They told him to contact Nippon Steel Chemical Co about providing the material. Roger has made contact with Nippon and is waiting to hear back from their sales representative. - Jim has heard from from his contacts at HERMES regarding polyimide film. They do not know of any companies that can provide the 1-mil Kapton with 25 micron copper. They did provide some follow up questions for us to answer. - Gerard has raised some points regarding material specification for the cathodes and that we need to put together a specification document. His concern was the minimum isolation resistance between adjacent strips at a specific test voltage. We will work to prepare a specification document based on input from the board house on their "standard" electrical checks. We will be sure that our required specifications are built into the contract. - One possibility that has come up is to move to a cathode with 5 micron of Copper if we can eliminate the 2-mm thick backing. This represents only a very modest increase in materials. It may be our only option ultimately. However, we shall see. - Fernando will do some calculations for the strip-to-strip capacitance to study signal propagation and noise. This work will begin after the systems review on May 7. In the mean time, Fernando will be given some cathode samples from the small-scale prototype. He will measure the strip-to-strip capacitance and scale the numbers up for the full-scale boards. Brian will provide the samples for Fernando. - Roger's test fixture for solder studies with the rigid-flex assemblies has arrived. This will be passed off to Greg Arnold's group to complete.
- The G10 order should have arrived and Brian will find out. Brian has all of the parts and pieces to begin construction of the full-scale prototype wire frames. DSC will work with Brian to prepare a construction time line for the wire frames so that they are ready to go to IUCF for the Phase 2 shortly after the completion of the Phase 1 winding. - The HV capacitors are expected to arrive by the end of May. These are the only components that have not yet been delivered. - The order for the cathode rigid flex assemblies (cathode daughter boards and cathode ground boards) has arrived. - No progress has occurred on modifying the aluminum construction jig as Brian has not yet gotten to this. Hopefully we can converge on completing this work before Brian goes to IUCF. - Clean room occupancy: Jack Segal is aware that we will need the space shortly. If possible, we would like to move all prototype detector construction into the clean tent. Only the mechanical prototypes should be done in the shop. - Second construction station: Brian will soon get to this PR. - Greg Arnold has asked us to provide information on what work we will need his group to perform and what the timelines are. Kim has provided information for the wire planes. Roger needs to provide information for the cathode planes and cathode daughter boards ASAP. - The rails and bearings could have been delivered. Bill will check into this. The folks at FSU will manufacture the attachment pieces once Bill provides drawings. This will happen after the review. - Fernando reported that the tool to attach the connectors to the SpectraStrip cable has finally arrived. No more c-clamps and prayers.
Test Frame Wire Winding
- Work at IUCF continues. The wire winding machine, tension measurement system, and wire position measurement system are all operational. IUCF is testing the wire position measurement system with an existing wire plan to finalize the measurement procedure and the parameters for the equipment. They are presently working on the construction of a support frame for the wire winding and the measurements. It looks like they will be ready for Brian to arrive on April 21. They hope to have the two planes wound by April 25. Note that IUCF has received the wire frames and strongback that we shipped out there. - 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
- Brian and Denny prepared another cathode plane, but there was a problem with the epoxy sample used and it did not harden. The cathode planes were therefore peeled off the frame. Brian and Denny will start again. - Brian is working to set up the laser measurement system from Acquity Laser that we received so that we can do some measurements of our cathode planes in a vertical position. We are concerned that the plane is too "floppy" and has too much gravitational sag (the old beer gut problem). The measurement should quantify this problem. - Brian will also work to make a "tensioned" cathode plane without the Rohacell backing. How much can we tension the planes without distorting the electrodes (or only distorting them within allowed tolerances)? Is the Rohacell (only 2-mm thick) actually worsening the problem? Of course, if we can successfully design a cathode plane without the Rohacell backing, the issue of sealing the Rohacell becomes moot.
- Fernando will supply an overall grounding specification document very soon. He is working on it.
Gas Volume Definition
- Dave Meekins has finally managed to get a model of the gas volume that his program can handle. This version is only twice the size of the nominal design. In this model, there is only the central beam hole in the cathode and the gas inlet is at the bottom of the space between the ground plane and the cathode plane. The gas outlet is at the top of the space between the neighboring cathode and ground plane. The results employed a 40/60 Ar/CO2 mixture. - We have received results with 3 volume exchanges per day and with 12 volume exchanges per day. A first glance at the results shows the at low flow rates, the gas is quite non-uniform and is quite unsatisfactory in terms of ensuring a uniform gas distribution in our drift space. The severity of the problem is reduced significantly at the higher flow rate, but is still not satisfactory. - What we need is for the calculation to tell us what a reasonable design should be for distributing gas in our chambers. - We need to work to come up with a design that allows the gas inlet and outlet on the spacer frame. This will allow for a single design for all layers. It may also be that we will need multiple gas inlets. Bill believes that this design can work with our current cathode design if we can allow for cathode through-holes at the top and bottom of the cathodes. The only space available is in the G10 frames, this needs to be looked into so that we can converge on a design.
- Kim has worked with Greg Arnold to update Fernando's original cleaning and soldering specification document for the wire frame PCBs. Fernando has review it and posted it on the GlueX portal as GlueX-doc-1016.
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 managed to restore his DAQ system after he got the new (used) computer. He has started a new run with the 40/60 gas mixture with the Hall B SIP preamplifiers and the charge integrating ADCs. This configuration will be studied before moving back to the ASICs.
- Fernando has prepared a document listing the studies necessary to complete with the ASICs for both the FDC and CDC. The goal is to complete this list of measurements in about one month. The main questions to be addressed are the dynamic ranges for the FDC anodes and cathodes. This information needs to be provided to Mitch Newcomer so that he can update the ASIC design for the June submission deadline. - The initial studies with the small-scale prototype will be carried out with the SIPs and charge-integrating ADCs to determine the dynamic range for required for both the anodes and cathodes. More details will be included in future minutes as we make progress with the measurements.
- The combined CDC/FDC meetings will be on Monday afternoons at 1:30 p.m.. A schedule for the rooms has been sent around. We will hold our first meeting on April 14. An agenda will be prepared and circulated. - DSC has provided an updated system budget to Elke. The big changes to the CD-2 baseline budget were the doubling of costs associated with the wire frame circuit boards and the addition of Roger's cathode daughter boards (which were not included at all in the original budget). These cost increases were balanced by a significant reduction in the signal cables costs. The overall budget was essentially unchanged compared to the 2007 version.
- 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.