FDC Weekly Meeting
Date: June 19, 2008
Participants: Daniel, Simon, Fernando, Kim, Roger, Micah
Next Meeting: June 26, 2008 @ 1:30 p.m.
- Roger has basically completed the cathode design drawings. He still has to make the Gerber files. He will send the design drawings to Fernando for final blessing before submission. Roger will also do a final check with Bill regarding the cathode hole locations before submission. - Roger is working with the Allflex representative to find whatever information is available from Nippon on the raw material specifications. - We discussed a suggestion from Allflex to split our PR in half. We discussed order two full sets of the 2 micron boards and the 5 micron boards and then do an extensive series of electrical and other QA checks before submitting the remainder of the order. This was viewed as a good thing for us to ensure that we do not spend all the money and have nothing to show for it should there be problems in the manufacturing process. - Roger passed on our list of handling specifications to Allflex and he will discuss with them any details that should be further investigated before ordering. - Roger believes that the cathode board PR should be completed and on Elke's desk before our next group meeting. - Additional solder tests of the rigid-flex assembly to the cathode board mock up will proceed after Roger gets the hot air pencil from Fernando. This work will wait until the cathode board PR is completed. - 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. Chuck is responsible for looking into this and letting us know. - Brian will modify his Lucite box design for storage of the completed cathode planes. The cathode planes can stack upon one another (unlike the strung wire frames). He will make some minor modifications to the existing box drawings and prepare the PR. This work will proceed in July when Brian gets back to town. - Bill found a precision straight edge 1.5 m long for $750. We can decide in the upcoming weeks if this is appropriate to purchase to cut our cathode boards to width.
- Greg Arnold's group completed the HV capacitor soldering on 5 sets of boards for the full-scale prototype. All boards have been delivered to Simon for storage. - The order for the 5 ft x 5 ft granite table has now gone out. The table will take 4 to 6 weeks to arrive. - The work to modify the existing aluminum tooling plate and make a second are in the queue in the JLab machine shop. This work should be completed within about 2 weeks. - Brian found that the power cord for the clean tent did not reach any of the recepticles in the clean room. He made a request to plant services to have an outlet installed. No update on this work. - Brian and Bill will work to update our wire frame construction sequence document. Brian will provide a first draft to Bill who will work to polish it up. We would like to provide this to Casey so his group (and of course ours) can full understand the procedures. This work has not yet gotten underway.
- No work done on cathode prototyping this week. Still need to pursue techniques to tension cathodes to a particular (pre-determined) point. We still need to pursue mechanical solutions (fixed weights to define the tension). More work when Brian returns from vacation. - We will try to develop a cathode tension measuring system using our laser measurement head. The procedure will be to direct a puff of air at the center of the cathode and measure the amplitude fluctuation vs. time through the laser measurement system. Fitting this amplitude distribution will give us (hopefully) the fundamental frequency that we should be able to convert into the membrane tension. More to come.
Test Frame Wire Winding
- We had a teleconference with IUCF and DSC and Keith at IUCF are working to put together an agreed upon task list that IUCF can use to provide a budget estimate for the completion of Phase 1. We expect to have a final task list completed this week and the Phase 1 continuation budget estimate in hand by the end of next week. - In the past week, the IUCF folks have figured out that the problem with the tension measurements was due to how well they controlled the air puff at the wire location. They have modified the system and have verified that the wire tensions are within reasonably well-controlled limits. For all intents and purposes, it looks like the problems with the wire tension are solved. - We have one frame ready to go to IUCF for the continuation of Phase 1. A second wire frame is being worked on in the JLab shop to add the through-holes to the frame. It is not yet clear when this will be completed, but we expect within two weeks. - 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.
Cathode Flatness Measurements
- Micah is working on upgrading the system readout electronics. He will also prepare a time line for the system work so that we can have a rough idea how he plans to make progress and complete the system upgrade and complete the required suite of measurements before the end of the summer when he disappears. - Micah will also put together a list of things that need to be purchased so that we can start the procurement process as soon as we can.
Cooling System Tests
- Denny reassembled the preamplifier cooling system in F117 and set the flow and temperature. Fernando is getting ready to perform the cooling system measurements. Bill has ordered a flow control valve that will arrive shortly and be installed in the system.
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 when we get a chance.
- 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.
- Simon and Fernando have redone the grounding layout on the small-scale prototype in an attempt to reduce the noise contributions to the FADC spectra. Their work has resulted in a noticeably quieter chamber response. This work was initiated after some concerns about the raw FADC spectra (those without a timing window cut to select out the good events). Cosmic ray data are now being acquired to double-check Simon's earlier data to ensure that the conclusions on the ASIC dynamic range do not change. Simon has also collected some 55-Fe source data. The pulse initially saturated the FADC (coming in a 2 V!). He attenuated the signals by a factor of two to fit them into the FADC range (which is 1 V). If we are to use this data to measure the chamber gain, we need to be able to see two energy peaks in the ADC spectra, but right now, only a single peak can be seen at about 800 mV in the ADC spectrum. Simon is investigating this at the current tme. - Simon has posted a first version of the FDC ASIC writeup. This work is posted as GlueX-doc-1070. Folks should look this over and provide feedback. This note still is missing the final specification for cathode and anode dynamic range, but Simon is working to converge on this.
- 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.