Difference between revisions of "Minutes-12-6-2012"

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#* Package testing (Lubomir)
 
#* Package testing (Lubomir)
 
# Corrosion [http://www.jlab.org/Hall-D/detector/fdc/corrosion/Spreadsheet.pdf tests] (Lubomir)
 
# Corrosion [http://www.jlab.org/Hall-D/detector/fdc/corrosion/Spreadsheet.pdf tests] (Lubomir)
−
# Engineering  
+
# Engineering (Bill)
 
# Electronics (Chris, Nick)
 
# Electronics (Chris, Nick)
−
# Tests at EEL126 (Lubomir)
+
# Tests at EEL126 [https://halldweb.jlab.org/elog-halld/FDC FDC E-log]
 
# Other
 
# Other
−
 
−
<!--
 
  
 
= Minutes =
 
= Minutes =
  
−
Participants: Eugene, Dave, Chris, Nick, Vlad, Simon, Beni, Glenn, and Lubomir.
+
Participants: Eugene, Bill, Dave, Chris, Nick, Simon, Beni, and Lubomir.
  
 
== Production ==
 
== Production ==
  
−
- Dave: now the techs are back and we are working on package #2. Tina and Mike are cutting/gluing new foils; Anatoly tested already the six new foil sets that we have received. Anatoly started gluing the daughter cards on the cathodes that were done before. Priority is to finish the two type-3 cathodes that will be needed in any package configuration.
+
- Dave: priority is to finish the two type-3 cathodes so that we can build three cells from package #2. The first type-3 will be ready on Monday, then we can start the installation. Working on all the other cathodes for this package. Since Tina and Mike will start working also on BCAL we'll have to find a way to finish at least the package#2 cathodes, that has to be done by the end of January.  
  
−
- On package #1 Vlad installed the ground connections before Thanksgiving, then this week we installed the cooling loops and yesterday Chris and Nick started working on the HV cabling. The package will be ready at the beginning of the next week. We decided not to install the cooling manifolds so far: we don't need them now and in case we need to open the package we will not be able to re-use the cooling tubes. On package #3 it turned out the splittings of the cooling tubes are in wrong places due to misinterpreting the drawings. Correcting this will take ~2 days but will do it later.
+
- Package #4: the broken wire (top cell) was replaced and the package put together last Friday. This week the top cell was tested: all channels working fine, very low currents of 15/-4nA, oxygen after six days flushing ~160ppm. The plan is to take the package from the installation table and start putting the other subsystems. The problem is that we still don't have the clips.
  
−
- Package #4 was assembled (the two missing cells) just before Thanksgiving and flushed with gas over the holidays: now oxygen is 151ppm. Vlad tested all the cells: currents on cells from #6 to #2: 21/-3, 44/-4, 42/-3, 50/-3, 110/-100 nA. Three cathode channels with bad contacts between the daughter cards and the pre-amps found; after removing/inserting the pre-amps they start working.  
+
- All the subsystems on package #1 were installed.
  
−
- On cell#1 package #4:HV could be applied only to several HV sectors +/-HV1, +/-HV4, and +HV3. On the rest we found shorts between the HV and the lower cathode and therefore we opened it today: as expected we found a broken wire, field 47. It is not clear when and how the wire broke. Certainly it was in place when the wire frame was installed in the package, but later after closing the package somehow it broke in the middle, the only explanation so far that it may have had a kink in this place (Casey). Also some wire frame deformation must be involved, say even on the pins it stayed deformed but after tightening the package got flat and the wire broke? The tension of the wire was 122g very close to its neighbors. Casey is replacing already the wire; the plan is to finish it by tomorrow so that we can put the package together before the weekend.
+
- Package #3: as explained in entry #98, the package was connected to the Nitrogen dewar with a rotameter at 30sccpm, and there was an over-pressure over the last weekend. We measured the pressure at the output of the rotameter: 360Pa, so the pressure in the chamber must have been lower than that.
  
−
== Cathode corrosion test ==
+
== Electronics ==
  
−
- Vlad: test #3 (Ar/CO2 gas, at ~70degC). Two samples failed before Thanksgiving (14 days from the start of the tests): one EPDM and the other dummy, i.e. no O-ring on the sample, just a strip with two wires soldered to the ends. The second EPDM sample is OK already 23 days. We assume it was the solder that failed again; it failed before at 100degC in four days. From these results one estimates about 0.5eV activation energy, which means this type of soldering on 2 micron copper would fail after ~190 days at room temperature, good we don't solder on 2 micron copper! As for the Viton+Apiezon the highest estimate so far is that it will survive for at least ~1300 days.
+
- Chris: delay with the clips due to lack of material. They made only 135 (out of 500) and Chris asked them to ship these; plus about 50 here could be enough for one package. Nick populated one more set of PCB and will do another (the last) one soon. Chris and Nick finished the HV cabling on package #1.
  
−
== Engineering ==
+
- According to Beni, Cody made progress in coding the firmware for fADC125 and will do some tests in 126.
  
−
- Without Bill not much to say.
+
== Cathode corrosion test ==
  
−
== Electronics ==
+
- Lubomir: test #3 (Ar/CO2 gas, at ~70degC). One more sample failed over the weekend, 25 days after the start of the test: one of the two Viton samples, second Viton is OK. Again we suspect it is the solder that failed.
  
−
- Chris: the ground clips were shipped will be here soon. Finally the daughter cards arrived and we started using them at Blue Crab. However, it turned out they have not been tested. Chris/Nick will take them n
+
== Engineering ==
−
ext week for testing, except the cards that were put on one cathode that will be tested at Blue Crab.
+
  
 +
- Bill ordered fiducial stuff the parts for the package spacers. All the parts for the cooling, except the chiller, are here. Will talk to the survey people about the details.
  
 +
- Bill complained about many corrupted files on the M-drive in the halld_engineering directory. Most of them have also files with the correct versions, but some, including several FDC procedures, don't.
  
 
== Tests at EEL126 ==
 
== Tests at EEL126 ==
  
−
- The third package was moved from 126 to Blue Crab before Thanksgiving. Before that Lubomir collected ~5 days data with the special three-cell-cathode configuration (as explained before in Elog #96) needed to extract the time-to-distance function and estimate the wire resolution. The new results with higher statistics and better track quality are shown in entry #97: the polynomial parametrization of this function is given there; the average wire resolution is estimated to be ~230 microns. This is an upper estimate since the cathode resolution is expected to be worse than the one estimated from the pickle-fence histogram.
+
- The two AC units in 126 are now installed, both the inside and outside parts, but not connected electrically; will happen next week.
  
−
- The A/C units for 126 were delivered today and the the plan is to start the installation on Monday. Tomorrow the techs will be there to clean the place: shelves, tool boxes etc.  
+
- Lubomir showed latest results for the wire resolution using the three-cathode configuration for the third package; details in the FDC Elog #99. After extracting experimentally the time-to-distance function using cathode information only, then the track can be reconstructed with a minimum number of cells. This first step is needed to find the offsets of all the wire planes. Then one can do the track fitting using all the planes except one (cell #2) on which we study the resolution. The residuals for cell #2 showed better resolution (second plot in #99), ~190 microns on average, than obtained before for cell #3. In case of cell #3 one had to take into account the strip resolution, and the value for that was too optimistic, this can explain the cell #2/3 resolution differences. Now the resolution is closer to that obtained with the prototype but without the time-to-distance conversion, except at big distances from the wire. There the field is not homogeneous and the statistics is very poor, both these can explain the problem.
  
−
- Related to that we decided to postpone the move of the first package for testing to 126. First, there will be installation work there, second, we expect the HVAC to be down for the Christmas holidays as it was last year. We will still have time to test package #1 in January and package #4 in February. By that time we will be ready with package #2.  
+
- The offsets of the wires were found w.r.t. frame defined by cells #1 and #4 and they are: -282, -116, +409, +147 microns for cells #2,3,5,6. So, somehow cell #5 is off by 200-300 microns. By design this should not happen if the strong-back doesn't move w.r.t pin-rails. The strong-back is attached to the granite table with micrometers that are locked, but Dave said sometimes these needed to be adjusted. We discussed if the Beni's results about deviations from 60deg cell rotation may have the same origin and related questions about surveying and extracting the offsets from the data.
  
−
- Beni plans to re-adjust the range of all mass flow controllers. The dynamic range is a factor of ten. A balance has to made if we want to be able to use gas mixtures in the range from 40/60 to 90/10 Ar/CO2 and a spare factor in case we want to increaser the flow to compensate for eventual gas contamination. After the meeting Beni and Lubomir decided: 1) to be able to change the gas mixture from 40/60 to 90/10, 2) have 250 sccpm nominal flow per package, 3) to have the possibility to increase the flow by a factor of 1.6 from the nominal, 4) to have identical flow controllers for Ar and CO2. The safety factor of 1.6 may seem low, but the point is that we know the gas contamination is now low, it is defined by the sealing technology used, and we don't expect significant deterioration.
+
== Other ==
 +
- Beni is working on the HV GUI for the FDC.  
  
−
-->
+
- Next FDC meeting will be January 3, due to the physics Christmas party next Thursday.

Latest revision as of 02:07, 1 April 2015

December 6, 2012 FDC meeting

Agenda

  1. Production Construction Tracking
    • Production status (Dave)
    • Package testing (Lubomir)
  2. Corrosion tests (Lubomir)
  3. Engineering (Bill)
  4. Electronics (Chris, Nick)
  5. Tests at EEL126 FDC E-log
  6. Other

Minutes

Participants: Eugene, Bill, Dave, Chris, Nick, Simon, Beni, and Lubomir.

Production

- Dave: priority is to finish the two type-3 cathodes so that we can build three cells from package #2. The first type-3 will be ready on Monday, then we can start the installation. Working on all the other cathodes for this package. Since Tina and Mike will start working also on BCAL we'll have to find a way to finish at least the package#2 cathodes, that has to be done by the end of January.

- Package #4: the broken wire (top cell) was replaced and the package put together last Friday. This week the top cell was tested: all channels working fine, very low currents of 15/-4nA, oxygen after six days flushing ~160ppm. The plan is to take the package from the installation table and start putting the other subsystems. The problem is that we still don't have the clips.

- All the subsystems on package #1 were installed.

- Package #3: as explained in entry #98, the package was connected to the Nitrogen dewar with a rotameter at 30sccpm, and there was an over-pressure over the last weekend. We measured the pressure at the output of the rotameter: 360Pa, so the pressure in the chamber must have been lower than that.

Electronics

- Chris: delay with the clips due to lack of material. They made only 135 (out of 500) and Chris asked them to ship these; plus about 50 here could be enough for one package. Nick populated one more set of PCB and will do another (the last) one soon. Chris and Nick finished the HV cabling on package #1.

- According to Beni, Cody made progress in coding the firmware for fADC125 and will do some tests in 126.

Cathode corrosion test

- Lubomir: test #3 (Ar/CO2 gas, at ~70degC). One more sample failed over the weekend, 25 days after the start of the test: one of the two Viton samples, second Viton is OK. Again we suspect it is the solder that failed.

Engineering

- Bill ordered fiducial stuff the parts for the package spacers. All the parts for the cooling, except the chiller, are here. Will talk to the survey people about the details.

- Bill complained about many corrupted files on the M-drive in the halld_engineering directory. Most of them have also files with the correct versions, but some, including several FDC procedures, don't.

Tests at EEL126

- The two AC units in 126 are now installed, both the inside and outside parts, but not connected electrically; will happen next week.

- Lubomir showed latest results for the wire resolution using the three-cathode configuration for the third package; details in the FDC Elog #99. After extracting experimentally the time-to-distance function using cathode information only, then the track can be reconstructed with a minimum number of cells. This first step is needed to find the offsets of all the wire planes. Then one can do the track fitting using all the planes except one (cell #2) on which we study the resolution. The residuals for cell #2 showed better resolution (second plot in #99), ~190 microns on average, than obtained before for cell #3. In case of cell #3 one had to take into account the strip resolution, and the value for that was too optimistic, this can explain the cell #2/3 resolution differences. Now the resolution is closer to that obtained with the prototype but without the time-to-distance conversion, except at big distances from the wire. There the field is not homogeneous and the statistics is very poor, both these can explain the problem.

- The offsets of the wires were found w.r.t. frame defined by cells #1 and #4 and they are: -282, -116, +409, +147 microns for cells #2,3,5,6. So, somehow cell #5 is off by 200-300 microns. By design this should not happen if the strong-back doesn't move w.r.t pin-rails. The strong-back is attached to the granite table with micrometers that are locked, but Dave said sometimes these needed to be adjusted. We discussed if the Beni's results about deviations from 60deg cell rotation may have the same origin and related questions about surveying and extracting the offsets from the data.

Other

- Beni is working on the HV GUI for the FDC.

- Next FDC meeting will be January 3, due to the physics Christmas party next Thursday.

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