November 11, 2010 FDC meeting
- Production (David)
- Blue Crab status sketch
- Frame lamination
- Production plan
- Electronics (Fernando, Chris, Roger)
- Update on PCB inspection
- Cathode foil production
- Rigid-flex procurement
- Engineering (Bill, David, Beni)
- Wire stringing status model ; stepper motor controller.
- Full-scale prototype tests
- timing with fADC125 (Beni)
- cathode resolution studies (Simon and Lubomir) FDC Log Book, pages 537-539
Participants: Eugene, Fernando, Bill, Casey, Mark, Chris, Roger, Al, Simon, Beni, and Lubomir.
- They are going to install phones and work on the Internet today at Blue Crab. We can now use heaters at low temperatures; must be above 60degF for gluing.
- By next Wednesday expect to have all the wire frames laminated. 18 frames came back from Vision machine after fly cut. They started there also the cathode frame production.
- Dave made the next version of the production plan. We start production in March 2011, the first package will be ready by September 2011 and then every ~4 months we plan to have a new package. According to the plan we will produce chamber by chamber serially, so that we can test them at the same time.
- Chris received all the populated PCBs. The inspection showed that the packaging was not done correctly (as for the first article) and as a result 8 PCBs (3+3+2 of different types) had broken tips up to 1.5". Bill thinks that this is not crucial and one should be able to glue the PCBs together. The main problem is that the PCBs have much more flux than the first article PCBs; the latter also were not acceptable. Fernando discussed the issue with the company and we will ship all the PCBs back for cleaning. In addition Chris found some other problems that are not crucial (Fernando). Find many pictures from the PCB inspection at M:\halld-electronics\Documents\FDC\Populated FDC First Articles on Windows, or at the /group/halld-electronics/Documents/FDC/Populated FDC First Articles on linux.
- Roger received the Gerber files from Allflex adjusted to the production, for final approval. Bill and Fernando looked at them and agreed. The first cathode foils will be produced in the week of 11/29-12/3. The rigid-flex contract was awarded with a company also near Minneapolis. We will have the first article also by the end of the month.
- Cathode foil inspection: George Jacob suggested moving the two tables inside the Hall B clean area in the evening before the week of 12/6-12/10, using the roll-up door, so that the particle count goes down by 12/6. We have one 2x5' table and need to find another one. Fernando: need to check the connectivity (resistance if measurable) for each strip, but also between the strips; the latter was an issue before. Fernando will send David the QA procedure for the cathode foils and the PCBs.
- Bill showed his model of the wire stringing table (linked above). He made improvements in the height adjustment of the strongback. The movement system will be attached to the sides of the table and movable over the chamber. There were different suggestions how to install it so that it's not obstructive when stringing. We discussed also how to calibrate/set starting point for the position measurements.
- Stepper motor controller: Beni tried to use JLab controllers from the target group to control the motor. It works only without using the encoder. Therefore, we will order a new controller from "Cross-Automation" for ~$3k. As for the software, it comes with low level, AcroBasic, and high level, AcrView software. There are drivers also for LabView (Dave) and we will ask for help from somebody in the lab familiar with LabView.
- Using laser sensor for position measurement: The laser sensor we use for foil tension measurements has low sampling rate (~1kHz) which is not good enough to measure frequenses of the order of several hundred Hz (Fernando). We will try with a free sample 200kHz sensor (Bill) and if it works for us we will buy it.
Full-scale prototype tests
- Beni is using now both, fADC and discriminator cards, for timing at different places on the top and middle chamber. He will be able to compare directly their performance, but has some software problems.
- Fernando found that one of the connectors for the discriminator card in the middle chamber is noisy. Beni: checking the connectors should be included in the QA procedure.
- Lubomir studied the cathode resolution as function of the strip multiplicity for different thresholds (page 539) using cosmics data. The strip multiplicity in the Simon's MC simulations (page 537) of ~4.5 corresponds to about 15mV threshold at 2 10^5 gas gain. At 40mV threshold the mean multiplicity goes down to ~3 but the resolution gets worse. The GlueX event size is dominated by the size of the data from the FDC cathodes. Therefore, this is a trade between resolution and event size.