Difference between revisions of "Minutes-8-30-2012"

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= Agenda =
 
= Agenda =
# Cathode production [http://www.jlab.org/Hall-D/detector/fdc/production/FDC_Construction_August_30_2012.xlsx Construction Tracking] (Dave)
+
# Production [http://www.jlab.org/Hall-D/detector/fdc/production/FDC_Construction_August_30_2012.xlsx Construction Tracking] (Dave)
 
# Cathode corrosion
 
# Cathode corrosion
 
#* Recent test results: [http://www.jlab.org/Hall-D/detector/fdc/corrosion/2012-08-30_09.26.58.jpg]
 
#* Recent test results: [http://www.jlab.org/Hall-D/detector/fdc/corrosion/2012-08-30_09.26.58.jpg]
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# Electronics (Chris, Nick)
 
# Electronics (Chris, Nick)
 
#* PCBs
 
#* PCBs
# Third package tests [https://halldweb1.jlab.org/elog-halld/FDC FDC E-log] (Beni)
+
# Third package tests [https://halldweb.jlab.org/elog-halld/FDC FDC E-log], [https://halldweb.jlab.org/elog-halld/FDC/71 Entry 71](Beni)
 
# [http://www.jlab.org/Hall-D/detector/fdc/general/tdr.pdf TDR, pages 132-145] (Lubomir)
 
# [http://www.jlab.org/Hall-D/detector/fdc/general/tdr.pdf TDR, pages 132-145] (Lubomir)
 
# Other
 
# Other
 
<!--
 
  
 
= Minutes =
 
= Minutes =
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== Production ==
 
== Production ==
  
- Dave: using the new tool to hold the cathodes flat, two cathodes moved to tables and the cards are being glued there.   
+
- Dave: working on all the cathodes for package #1. Using the new tool to hold the cathodes flat, two cathodes moved to tables and the cards are being glued there. Will have cathodes for the first, second, and third cells by next Tuesday, next Thursday, and next next Tuesday respectively. This is assuming one cathode per day, which is limited by the tools that we use now.
  
- The third package is ready with the subsystems: grounding, cooling tubes, HV cabling. The plan is to move it to 126 tomorrow. The grounding worked fine, Vlad put ~100 clips for grounding as planned and another ~100 attached close to both sides of the cards (where possible and needed) to prevent the cathode deformation at the periphery. As Casey suggested, we used a new method to install the cooling tubes. We tightened the bracket on one card in the middle of the tube and installed the rest of the brackets loose. Then, going from the middle card toward the two ends of the tube we tightened the rest of the brackets. Thus, the copper tubes apply some pressure on the cards; before we had problems with some of the cards being pulled by the tubes. Gluing of the back brackets with green epoxy to the tubes was done at the end. In 126 after installing the cables we should experiment how easy will be to remove the extra clips we put on the card sides.
+
- Wire frames: Chris will put the resistors on the first PCB set next week. Then we will start laminating the wire plane #29, we have a frame for it. The other three G10 wire frames will come from the machine shop in ~2 weeks. Fernando and Bill confirmed that the new PCBs can be used.  
 +
 
 +
- Roger got quotations from Allflex and Flexible Circuits, the two Minnesota companies that made the cathode foils and the rigid-flex assemblies. According to Allflex they have material for 18-19 foils and we asked for 20. We will need the foils for some of the cathodes on package #2. Based on Dave's estimations for the refurbishment of the first package and then completion of the fourth one, we will need the foils sometime in November-December. In any case it's better to submit the PRs now and contact Eugene to use funds (~$26K) from FY12, if possible?
  
 
== Cathode corrosion ==
 
== Cathode corrosion ==
  
- New SEM results from Olga (follow the above link) for the samples from the Vlad's test with the vacuum chamber; the chamber had water inside and the temperature at end of the day (lamps were off overnight) was close to 100degC. The test was done for about 4 days:  
+
- The last test with the vacuum chamber: we had a sample with Viton+Apiezon, three O-ring pieces across a strip using the strong (red) clamp and keeping it for one week at high temperature and humidity, the longest time so far. The picture of the sample is linked above: copper changed color everywhere except at the place where the Apiezon was applied. Several dark lines are visible at the O-ring positions. Two on the sides are darker, probably they took the main pressure from the clamp. Only in the middle we see some very small holes through the copper, visible only with a good back-light. Olga will do SEM analyses.
  
*Copper foil with EPDM inside: significant corrosion, a lot of sulfur present.
+
- This is the first time we had dark traces under the Vition+Apiezon O-rings, though the conditions of the above test were extreme and we see corrosion/oxidation everywhere on the sample. To make sure we have the right pressure on the Viton we started a new test with a real spacer ring "inserted" through the vacuum chamber and applying pressure on it with a lead brick.
+
*With the EPDM of the gasket, part of the foil strips were inside the gas chamber and part exposed to the air: no sulfur seen at the air side and a lot of it at the gas side. However, inside the gas volume there was moisture and the temperature was much higher than outside. We had seen corrosion before also in the samples placed in air with some water put on the foils and no heating. We will do more tests.  
+
  
*Copper foil with Viton: some traces visible, almost no sulfur there but some chlorine. Tim suggested cleaning the O-rings before installation.
+
== Conductive tape studies ==
  
*With Viton and Apiezon: no visible corrosion, only copper and carbon lines are visible, but the grease was not cleaned. Olga will repeat the measurements after cleaning it. 
+
- Vlad did the same ball counting studies as before, but with another cathode (#4, one of the worst: top of former package #1) this time using improved technique in removing the conductive tape and measuring the resistances. The correlation between the resistances and the ball numbers is much more evident now (profile plot above). Again we have about 0.5-2 Ohms per ball and all the resistances above several Ohms (~10-15%) can be explained by loose contacts between the balls and the cathode traces. The highest resistance on this cathode was 50 Ohms.
 
+
- The first testing chamber with production wire frame and cathodes was opened yesterday, exactly 4 weeks operating with HV and gas. Some traces from the EPDM O-ring are visible but it doesn't look like the corrosion on the first and second packages. We conclude that the humidity is an important factor. No traces on the cathode against the Viton+Apiezon O-ring are visible. The test with the small-scale prototype is running two weeks, haven't opened it yet.
+
 
+
- Tim for the humidity conditions in the Hall: nominally it will be less than 45%, but he can't exclude some periods when it might be higher. There will be dry air blowing through the magnet. We should avoid opening the Hall doors for a long time during the installation.
+
  
 
== Engineering ==
 
== Engineering ==
  
- We will have two strong-backs to be used to grab the cathodes from both sides and keep them flat. We discussed how to support the cathode periphery when using the strong-backs. Casey made a table with rods that will be used to store the cathodes in a flat position.
+
- The cathode strong-back tool needs more suction cups. The six that we have now are enough for type-1 but not for type-2/3. Will have them on Tuesday and then can continue with the cathode production. Bill suggested installing a gauge to make sure the vacuum is OK before lifting the cathode.
 
+
- The rings for the cathode strong-backs came from the REX company right after the meeting, but there were issues with the fittings for the suction cups; also the weight of the aluminum ring seams too big.  
+
 
   
 
   
 
== Electronics ==
 
== Electronics ==
  
- Fernando: wrong zip file was send to the company for the PCBs; now all the files have the correct names to exclude such a problem.  
+
- Fernando did some organization of the files for all the FDC electronic parts; he also got the latest versions from Roger. Now the production files are separated from the older versions.  
  
- Main discussion was what to do the with these four PCB sets. Mechanically, compared to the original PCBs, there is a small difference in the gas connector positions (about a mm); according to Tim it will work and mechanically the wire planes will be interchangeable. Fernando: some of the signal traces are at different positions and the gold-plated ground area is bigger; the traces going through that area have to be covered with conformal coating. There should be no differences in the HV PCBs, but Fernando will check all the boards and on Monday we will decide if these can be used. Eugene: if you spend more than two weeks on these boards we better purchase new ones, which however will be tricky (at the end of the fiscal year) and will delay the production. Lubomir and Dave: we will need the boards in two weeks, if not we have to re-work the schedule.
+
- Fernando explained the status with the fADC125. Beni and Cody did some tests: the problem is the bus communication, not in between the FPGAs.
  
== TDR ==
+
== Third package tests ==
  
- Lubomir received corrections from Bill and Simon, still some work remains to be done here.
+
- Third package was moved to 126 last Friday, started bubbling immediately, flushed with gas (40/60 Ar/CO2) over the weekend.  
  
== Other ==
+
- Beni: Nominal HV (+2100/-500V) was applied starting Monday without problems, except one negative (field wires) HV sector on the bottom (#6) cell that trips from time to time. For the overnight measurements there we applied +2250V on the sense wires only.
  
- Eugene urges us to do all the purchases for the FDC as soon as possible at least by the beginning of September; after that most likely there will be no money till the end of FY12.
+
- Linux DAQ works now for the TDCs only, there was a problem with byte swapping. First results are linked above from the FDC E-log:
 +
# Efficiency: much better than with the first package (means oxygen % very low) in the 95-100% range, and if needed we can increase the HV. However more studies are needed; the efficiency is not so great when applying timing cuts.
 +
# Noise in the second cell. After the meeting it turned out that we missed one ground connection there. After installing it the noise seamed to disappeared.
 +
# TDC spectra look nice and uniform with two peaks well defined, corresponding to the position of the sense and field wires. The spectrum for the HV sector without field voltage  is much wider.
 +
# Missing half of cell #3 due to translator board problem, now being repaired by Cody.
 +
 
 +
== TDR ==
  
-->
+
- Latest version posted. FDC electronics subsection: we should give details up to the pre-amp level. The rest of the electronics (fADC125, F1TDC, ...) should be in the "Electronics" section.

Latest revision as of 05:48, 1 April 2015

August 30, 2012 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
  2. Cathode corrosion
    • Recent test results: [1]
  3. Conductive tape studies: [2], [3], [4],[5], [6] (Vlad)
  4. Engineering (Bill)
    • Cathode strong-backs
  5. Electronics (Chris, Nick)
    • PCBs
  6. Third package tests FDC E-log, Entry 71(Beni)
  7. TDR, pages 132-145 (Lubomir)
  8. Other

Minutes

Participants: Fernando, Bill, Dave, Elton, Simon, Chris, Vlad, Beni, and Lubomir

Production

- Dave: working on all the cathodes for package #1. Using the new tool to hold the cathodes flat, two cathodes moved to tables and the cards are being glued there. Will have cathodes for the first, second, and third cells by next Tuesday, next Thursday, and next next Tuesday respectively. This is assuming one cathode per day, which is limited by the tools that we use now.

- Wire frames: Chris will put the resistors on the first PCB set next week. Then we will start laminating the wire plane #29, we have a frame for it. The other three G10 wire frames will come from the machine shop in ~2 weeks. Fernando and Bill confirmed that the new PCBs can be used.

- Roger got quotations from Allflex and Flexible Circuits, the two Minnesota companies that made the cathode foils and the rigid-flex assemblies. According to Allflex they have material for 18-19 foils and we asked for 20. We will need the foils for some of the cathodes on package #2. Based on Dave's estimations for the refurbishment of the first package and then completion of the fourth one, we will need the foils sometime in November-December. In any case it's better to submit the PRs now and contact Eugene to use funds (~$26K) from FY12, if possible?

Cathode corrosion

- The last test with the vacuum chamber: we had a sample with Viton+Apiezon, three O-ring pieces across a strip using the strong (red) clamp and keeping it for one week at high temperature and humidity, the longest time so far. The picture of the sample is linked above: copper changed color everywhere except at the place where the Apiezon was applied. Several dark lines are visible at the O-ring positions. Two on the sides are darker, probably they took the main pressure from the clamp. Only in the middle we see some very small holes through the copper, visible only with a good back-light. Olga will do SEM analyses.

- This is the first time we had dark traces under the Vition+Apiezon O-rings, though the conditions of the above test were extreme and we see corrosion/oxidation everywhere on the sample. To make sure we have the right pressure on the Viton we started a new test with a real spacer ring "inserted" through the vacuum chamber and applying pressure on it with a lead brick.

Conductive tape studies

- Vlad did the same ball counting studies as before, but with another cathode (#4, one of the worst: top of former package #1) this time using improved technique in removing the conductive tape and measuring the resistances. The correlation between the resistances and the ball numbers is much more evident now (profile plot above). Again we have about 0.5-2 Ohms per ball and all the resistances above several Ohms (~10-15%) can be explained by loose contacts between the balls and the cathode traces. The highest resistance on this cathode was 50 Ohms.

Engineering

- The cathode strong-back tool needs more suction cups. The six that we have now are enough for type-1 but not for type-2/3. Will have them on Tuesday and then can continue with the cathode production. Bill suggested installing a gauge to make sure the vacuum is OK before lifting the cathode.

Electronics

- Fernando did some organization of the files for all the FDC electronic parts; he also got the latest versions from Roger. Now the production files are separated from the older versions.

- Fernando explained the status with the fADC125. Beni and Cody did some tests: the problem is the bus communication, not in between the FPGAs.

Third package tests

- Third package was moved to 126 last Friday, started bubbling immediately, flushed with gas (40/60 Ar/CO2) over the weekend.

- Beni: Nominal HV (+2100/-500V) was applied starting Monday without problems, except one negative (field wires) HV sector on the bottom (#6) cell that trips from time to time. For the overnight measurements there we applied +2250V on the sense wires only.

- Linux DAQ works now for the TDCs only, there was a problem with byte swapping. First results are linked above from the FDC E-log:

  1. Efficiency: much better than with the first package (means oxygen % very low) in the 95-100% range, and if needed we can increase the HV. However more studies are needed; the efficiency is not so great when applying timing cuts.
  2. Noise in the second cell. After the meeting it turned out that we missed one ground connection there. After installing it the noise seamed to disappeared.
  3. TDC spectra look nice and uniform with two peaks well defined, corresponding to the position of the sense and field wires. The spectrum for the HV sector without field voltage is much wider.
  4. Missing half of cell #3 due to translator board problem, now being repaired by Cody.

TDR

- Latest version posted. FDC electronics subsection: we should give details up to the pre-amp level. The rest of the electronics (fADC125, F1TDC, ...) should be in the "Electronics" section.