Difference between revisions of "Minutes-9-29-2011"

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September 22, 2011 FDC meeting
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September 29, 2011 FDC meeting
  
 
= Agenda =
 
= Agenda =
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# Engineering update (Bill)  
 
# Engineering update (Bill)  
 
# Electronics update (Chris)
 
# Electronics update (Chris)
−
# Chamber testing at EEL126 (Beni)
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# Chamber testing at EEL126  
 +
#* Status (Beni)
 +
#* Cathode resolution of the second cell (Lubomir) [http://www.jlab.org/htbin/PHYSICS/halld/enote112.pl?nb=notebook&action=view&page=578]
 
# Other
 
# Other
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<!--
 
  
 
= Minutes =
 
= Minutes =
  
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Participants: Eugene, Bill, Dave, Chris, Simon, Beni, Vladimir, Mark, and Lubomir. Vladimir is the new graduate student from MePhi Moscow.   
+
Participants: Bill, Dave, Chris, Simon, Beni, Vladimir, and Lubomir.   
  
 
== Production ==
 
== Production ==
  
−
- Dave: started checking the continuity before taking the frame out of the stringing table: on the wire frame for cell#5 (that was just finished) one broken wire was found and was fixed today. Epoxy will cure overnight and tomorrow we will put on the stringing table the wire frame for cell#3 to fix one wire there too. Wire frame for cell#4 is ready, just needs final cleaning. On the last cathode (for the first package) the rigid-flexes were glued to the cathodes. Next, they will be tested with a generator and then the daughter cards glued.  
+
- Dave: Working on the sixth (last) wire frame for the first package; all wires soldered and today will do tension measurements. The fifth wire frame will be populated tomorrow by Chris. On Monday we will do the wire deadening on that frame and then it will be ready for stacking. Started working on the end windows and first cathode for the package #2.
  
−
- We discussed the reason for these broken wires, so far we had always one broken wire per plane. On the last one found on the frame for cell#5, we looked with a microscope. The wire was broken at the end of the epoxy right where it touches the soldering pad. The wire tip was bent at ~90 deg at this place somehow. It was not clear if the tip was inside or outside of the epoxy. The wire was checked by doing tension measurements on it. The only operation that happened later was cutting the wires and then doing the continuity measurements. One explanation could be a cold solder and then the wire brakes when twisting it. Dave suggested also that if the wire is above the PCB it may not be fully covered with epoxy and is easily breakable a that point. 
+
- We have four cells in the first package as of Tuesday evening. Finally we fixed the gas leak in the second cell (at the third attempt): a bubble in the epoxy inside  the chamber (that seals the gap between the solid part of the g10 and the PCBs) made a path for the gas to leak. A missing part of the trace  on a signal wire in the third cell was fixed by Dave. All the channels of all the wire planes and cathodes were checked with a generator prior the installation. We had to replace the top spacer ring because it turned out after the first installation that the gas openings were not drilled there. Bill proposed to check the flow trough the gas openings relatively, using a rotarmeter with a fixed impedance.  
−
+
−
- End of last week we put three cells in the package after replacing two wires in the second cell and changing all the O-rings.
+
−
The first three cells were tested channel by channel by Vladimir. All were OK except no signal on one wire channel in the new third cell, most likely broken wire. The third cell was conditioned with HV relatively fast, but then suddenly developed very high current; we left it over the night at 1kV and then in the morning it was OK again.  
+
  
−
- We found again gas leakage with the three cells in about the same area as with the two cells. The amount of leakage was about the same (bubbling above 80-100 ccpm) as with the two cells, indicating that the problem is in the second cell. Bill suspects it is the seam on the wire frame between the PCBs that may have been somehow damaged during the installation. To fix the broken wire and look at the leakage place we decided to unstack the package down to the second wire frame. After finding the broken wire on the frame that is on the stringing table we decided to continue with this tomorrow.  
+
- Lubomir: we could not have the stack with the four cells bubbling when using a many-fold at the output. That's why we separated the outputs and put additional impedance at the output tubings: 2m long thin tubes. That resulted in almost equal pressure in all the chambers of ~30Pa at 40 ccpm total gas flow. The pressure inside the chamber was different by up to 10Pa when using the many-fold. No explanation of this effect, but just adding thin tubes at the output is a simple solution; at the same time it will prevent over-pressure.
  
 +
- Vladimir started already testing the package: yesterday he checked the third cell, today he was working on the second cell. The new fourth cells is not conditioned yet: we are at +1500/-500V now. Finally we have the 55Fe source (from RadCon) at Blue Crab and not only the testing is much faster but one can compare the amplitudes at the different channels.
 +
 
 
== Engineering ==
 
== Engineering ==
  
−
- Bill: the new fixture and hubs with adjustable height should be ready by the end of the month. Probably we will use them for the second package. The first fixture also can be refurbished to be used with the new hubs. Two more gusset rings ready tomorrow. Parts for the HV brackets and cooling system are also out for production. After the meeting: the package support brackets will be at JLab today.  
+
- Bill: has drawings of many parts and tools ready, but waiting for the new fiscal year: new hubs and fixture, cathode pusher, endoscope holder.
 +
 
 +
- Bill will design protective covers (out of some plastic). They will stay on the package during transportation and most of the tests can be done also with them. Bill also explained his ideas about the connections between the packages, the order of installation and the cabling. Since there will solid g10 cylinders between the packages we can remove the protective covers inside but will keep the two outer covers till the final installation.    
  
 
== Electronics ==
 
== Electronics ==
  
−
- Anatoly tested several fresh PCBs: no broken resistors, but few resistors down to 50%. So, most likely the resistors were broken by us while making the frames, but the resistors with deviations from the nominal value came from the manufacturer. Fernando was surprised (before the meeting) and suggested replacing those that are more than 10% off, although these are current limiting resistors, i.e. not so critical. No explanation how this may have happened during the population of the boards, since these resistors are at different places on the different boards.
+
- Chris working on the extension board to look directly at the signals from daughter cards; had questions about the pin configuration that we need.
 +
 
 +
- For the first package tests we need the pre-amp card to hold the cooling tubes that we will use also as a ground. These could be also dummy cards and we discussed what is the best approach. Without information from Fernando when we will have we the pre-amps ready we could not decide. So far we have 10 first article cards.  
  
 
== Chamber testing at 126  ==
 
== Chamber testing at 126  ==
  
−
- Beni raised several issues about the testing set-up. Designed with Mark a frame for the cable trays. Not clear how to organize the low voltage supply, should discuss it with Fernando. Also there's no final design yet of the cooling system; we discussed also what liquid to be used. fADC125: Gerard thinks the last FPGA (that gets the data from all the channels) doesn't have enough power for the needed functions and has to be replaced with a better one (according to Cody). The modifications will delay the production. The hope is that there will be pre-production of 20 units and we can use a good fraction of them for the FDC tests.
+
- Beni and techs made a lot of progress in 126: new cable frame is installed, now working on the cables and the new crate, need more F1TDC.
−
 
+
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- Lubomir: we moved the second cell from 126 to Blue Crab and opened it. The wire plane had ~2 MOhm between field and sense wires on HV sector #4 and that was confirmed after opening. A spot was found close to a field and sense wire at the signal side in the same sector. Also some corrosion is visible on the soldering pads close to the spot, indicating it could be reactive. Trying to clean that spot reflects directly the resistance. Not clear what the material is: semi-transparent like epoxy or Humi-seal?, can be removed by a wooden stick. Not clear at all how did it get there inside the gas volume.
+
  
 +
- Lubomir showed results about the resolution of the second cell (page 578 FDC electronic logbook). Eugene needed such plots for the Lehman review. Beni will modify also some of his results at pages 572-573, about the chamber efficiency and drift time spectra.
 +
 
 
== Other ==
 
== Other ==
  
−
New pictures of the three cell package are linked above.
+
No meeting next week due to the collaboration meeting at the same time.
−
 
+
−
-->
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Latest revision as of 10:13, 30 September 2011

September 29, 2011 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
    • Status
    • First package tests (Lubomir)
  2. Engineering update (Bill)
  3. Electronics update (Chris)
  4. Chamber testing at EEL126
    • Status (Beni)
    • Cathode resolution of the second cell (Lubomir) [1]
  5. Other

Minutes

Participants: Bill, Dave, Chris, Simon, Beni, Vladimir, and Lubomir.

Production

- Dave: Working on the sixth (last) wire frame for the first package; all wires soldered and today will do tension measurements. The fifth wire frame will be populated tomorrow by Chris. On Monday we will do the wire deadening on that frame and then it will be ready for stacking. Started working on the end windows and first cathode for the package #2.

- We have four cells in the first package as of Tuesday evening. Finally we fixed the gas leak in the second cell (at the third attempt): a bubble in the epoxy inside the chamber (that seals the gap between the solid part of the g10 and the PCBs) made a path for the gas to leak. A missing part of the trace on a signal wire in the third cell was fixed by Dave. All the channels of all the wire planes and cathodes were checked with a generator prior the installation. We had to replace the top spacer ring because it turned out after the first installation that the gas openings were not drilled there. Bill proposed to check the flow trough the gas openings relatively, using a rotarmeter with a fixed impedance.

- Lubomir: we could not have the stack with the four cells bubbling when using a many-fold at the output. That's why we separated the outputs and put additional impedance at the output tubings: 2m long thin tubes. That resulted in almost equal pressure in all the chambers of ~30Pa at 40 ccpm total gas flow. The pressure inside the chamber was different by up to 10Pa when using the many-fold. No explanation of this effect, but just adding thin tubes at the output is a simple solution; at the same time it will prevent over-pressure.

- Vladimir started already testing the package: yesterday he checked the third cell, today he was working on the second cell. The new fourth cells is not conditioned yet: we are at +1500/-500V now. Finally we have the 55Fe source (from RadCon) at Blue Crab and not only the testing is much faster but one can compare the amplitudes at the different channels.

Engineering

- Bill: has drawings of many parts and tools ready, but waiting for the new fiscal year: new hubs and fixture, cathode pusher, endoscope holder.

- Bill will design protective covers (out of some plastic). They will stay on the package during transportation and most of the tests can be done also with them. Bill also explained his ideas about the connections between the packages, the order of installation and the cabling. Since there will solid g10 cylinders between the packages we can remove the protective covers inside but will keep the two outer covers till the final installation.

Electronics

- Chris working on the extension board to look directly at the signals from daughter cards; had questions about the pin configuration that we need.

- For the first package tests we need the pre-amp card to hold the cooling tubes that we will use also as a ground. These could be also dummy cards and we discussed what is the best approach. Without information from Fernando when we will have we the pre-amps ready we could not decide. So far we have 10 first article cards.

Chamber testing at 126

- Beni and techs made a lot of progress in 126: new cable frame is installed, now working on the cables and the new crate, need more F1TDC.

- Lubomir showed results about the resolution of the second cell (page 578 FDC electronic logbook). Eugene needed such plots for the Lehman review. Beni will modify also some of his results at pages 572-573, about the chamber efficiency and drift time spectra.

Other

No meeting next week due to the collaboration meeting at the same time.

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