Difference between revisions of "Minutes-2-17-2011"

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== Production ==
 
== Production ==
  
- Dave: the stringing table and the cathode tensioning system are the only main items not yet moved to Blue Crab. The stringing table will be modified before moving there: 6 holes in the granite have to be drilled and different other new pieces mounted there. Will have three computers in the clean room, one new and another two used, all Windows. The temperature in the clean room is lower than the required one and the vendor will fix the problem tomorrow. It turned out the temperature control is not in the clean room and we are not supposed use it.     
+
- Dave: the stringing table and the cathode tensioning system are the only main items not yet moved to Blue Crab. The stringing table will be modified before moving there: 6 holes in the granite have to be drilled and different other new pieces mounted there. Will have three computers in the clean room, one new and another two used, all Windows. The temperature in the clean room is lower than the required one and the vendor will fix the problem tomorrow. It turned out the temperature control is not in the clean room and we are not supposed to use it.     
  
 
- The plan for the next month work at Blue Crab includes: cathode frame inspection, building PCB rings, cutting, aligning, and gluing cathodes. We will start with old PCB and
 
- The plan for the next month work at Blue Crab includes: cathode frame inspection, building PCB rings, cutting, aligning, and gluing cathodes. We will start with old PCB and
Line 31: Line 31:
  
 
- Dave's working on the procedures/travelers, we can't start production without these documents.
 
- Dave's working on the procedures/travelers, we can't start production without these documents.
 +
 +
- Bill asked if we need summer students for some work starting end of May.
  
 
== Electronics ==
 
== Electronics ==
Line 36: Line 38:
 
- Chris: 50 cables were reworked, but 13 of them came short by a foot. It turned out those are CDC type cables. Even if the length is not critical, we decided not to accept such cables for the FDC. Simon was concerned that we need a plan how to bundle, run the cables. Bill has some preliminary drawings, but everybody agrees that this is important.
 
- Chris: 50 cables were reworked, but 13 of them came short by a foot. It turned out those are CDC type cables. Even if the length is not critical, we decided not to accept such cables for the FDC. Simon was concerned that we need a plan how to bundle, run the cables. Bill has some preliminary drawings, but everybody agrees that this is important.
  
<!--
+
- The rigid-flex will be produced as it was in the first article. We requested additional 140 flexes to be used for exercising and as spares in case of cathode foil failure. In total we will have 615 flexes.
  
 
== Engineering ==
 
== Engineering ==
  
- Bill is working on several modifications of the stringing system:  
+
- There was a long discussion what we have learned from the stringing:
* protector cover for the wires needed during the soldering,
+
* modification of the pin rail to correct for the pitch that is ~250 microns off,
+
* monuments to be attached to the granite table and the strongback (three on each) and will be used as reference points to align the strongback to the wire positions,
+
* tool to be used for taping the wires down.
+
  
- Lubomir showed results for the position and tension measurements (page 551) on the first (test) wire plane built at JLab. First plot: deviation from the nominal position vs nominal position. It shows 1) a slope that can be explained by an angle of 25mrad (as shown on the second plot) of the measurement direction, or by a pitch bigger than 5mm; 2) there's jump in the positions close to the middle of the chamber, a result of one pitch being off by ~250microns (as measured with a micrometer), the change of the pitch is the same for the field and sense wires. We discussed what is the best way to correct for the offset: to cut and re-adjust the pin jig, or just to build a new pin jig. Bill will discuss it with the machine shop people.
+
# Bill questioned whether the wire vibration (used in tension measurement) is the reason for the several broken wires between the epoxy and the solder. Suggested using computer to control the amplitude and frequency of the generator. Dave will try connecting to the generator with LabView. Lubomir thinks the wires were broken by the leads while trying to keep them on the solder. The use of conductive rubber (from Fernando) will prevent this because one can put the leads away from the soldering pad. Bill suggested using pogo pins so that fewer people can do the measurements.
 +
# To prevent wire breaks at that place we can put later additional epoxy to cover the wires at that region, but Bill wants to avoid having epoxy on the solder.
 +
# Bill wants to try soldering before gluing. Lubomir: in this case it will be difficult to cover the wires to prevent from solder balls, without touching the wires.
 +
# We discussed again different types of solder and epoxy we and other groups have used.
 +
# Bill wants to make tools for the wire taping.
 +
# Lubomir is concerned having magnets (for the weight shield) close to the weights because of the possibility for attracting the weights and wire breaking.
  
- Tension measurements of all the wires of the test wire plane are shown at the bottom plot at page 551. Generally the tensions of the shortest wires deviate from the mean which can be explained by not using the right length, or other effects like the edge of the board affecting the vibrations. As Bill predicted, we found that the epoxy itself is not strong enough to keep the tension especially on the field wires. We were able to measure the tensions only after soldering the wires. The other problem was that the tension of the sense wires were 50% higher. After the meeting Lubomir found it was his fault, just using wrong density for the sense wires. The picture that is linked above is now the correct one.
+
- Bill wants to know if we can use aceton, it's need for the cathodes. Lubomir will study this issue.  
  
- A new type of conductive glue came from CMU used in the CDC and we will try it soon. Beni: it is used at different places in the straws but they don't measure the conductivity of the connections. Curtis: Correction, CMU measures that each straw is electrically connected to its donut after the glue has cured. What is not measured is the connection from the donut to the endplate as the risk in damaging the inside of the straw is larger than the risk of the donut to feed-thru to endplate connection being problematic. We also note that the glue joint is not conductive until after the glue has cured for 24 hours.
+
- The CMU conductive epoxy will be tested soon. We can have more from CMU.
  
== Full-scale prototype tests ==
+
== Chamber testing ==
  
- Lubomir showed few more plots (bottom two plots on page 550) demonstrating how the ratio top/bottom strip signals changes over the plane for the individual wires. On the bottom chamber the effect (if any) is much smaller. We discussed different ways of troubleshooting the problem: changing the flow in the chamber in different ways, measuring the pressure in the chambers, disassembling the ground/cathode plane package.
+
- Beni started discussing what is needed for the full package tests that will start in the middle of the next year (see the above link). It will be a multi-crate system that require new modules. The only concern so far are the F1TDCs that will not be ready by that time. Instead we have to use the old F1TDCs with translation boards.
  
-->
+
- Lubomir is scanning the middle chamber. The variations of the bottom/top strip ratio are as big as for the top chamber.

Latest revision as of 10:14, 18 February 2011

February 17, 2011 FDC meeting

Agenda

  1. Production (David)
    • Blue Crab status
  2. Electronics (Fernando, Chris, Roger)
    • Rigid-flex and foil production status
    • Other
  3. Engineering (Bill, David, Lubomir)
  4. Chamber testing
  5. Other


Minutes

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

Production

- Dave: the stringing table and the cathode tensioning system are the only main items not yet moved to Blue Crab. The stringing table will be modified before moving there: 6 holes in the granite have to be drilled and different other new pieces mounted there. Will have three computers in the clean room, one new and another two used, all Windows. The temperature in the clean room is lower than the required one and the vendor will fix the problem tomorrow. It turned out the temperature control is not in the clean room and we are not supposed to use it.

- The plan for the next month work at Blue Crab includes: cathode frame inspection, building PCB rings, cutting, aligning, and gluing cathodes. We will start with old PCB and damaged cathode foils and then use the new/good ones. The ultimate plan is to build parts for one chamber that has to be tested before the mass production.

- Dave's working on the procedures/travelers, we can't start production without these documents.

- Bill asked if we need summer students for some work starting end of May.

Electronics

- Chris: 50 cables were reworked, but 13 of them came short by a foot. It turned out those are CDC type cables. Even if the length is not critical, we decided not to accept such cables for the FDC. Simon was concerned that we need a plan how to bundle, run the cables. Bill has some preliminary drawings, but everybody agrees that this is important.

- The rigid-flex will be produced as it was in the first article. We requested additional 140 flexes to be used for exercising and as spares in case of cathode foil failure. In total we will have 615 flexes.

Engineering

- There was a long discussion what we have learned from the stringing:

  1. Bill questioned whether the wire vibration (used in tension measurement) is the reason for the several broken wires between the epoxy and the solder. Suggested using computer to control the amplitude and frequency of the generator. Dave will try connecting to the generator with LabView. Lubomir thinks the wires were broken by the leads while trying to keep them on the solder. The use of conductive rubber (from Fernando) will prevent this because one can put the leads away from the soldering pad. Bill suggested using pogo pins so that fewer people can do the measurements.
  2. To prevent wire breaks at that place we can put later additional epoxy to cover the wires at that region, but Bill wants to avoid having epoxy on the solder.
  3. Bill wants to try soldering before gluing. Lubomir: in this case it will be difficult to cover the wires to prevent from solder balls, without touching the wires.
  4. We discussed again different types of solder and epoxy we and other groups have used.
  5. Bill wants to make tools for the wire taping.
  6. Lubomir is concerned having magnets (for the weight shield) close to the weights because of the possibility for attracting the weights and wire breaking.

- Bill wants to know if we can use aceton, it's need for the cathodes. Lubomir will study this issue.

- The CMU conductive epoxy will be tested soon. We can have more from CMU.

Chamber testing

- Beni started discussing what is needed for the full package tests that will start in the middle of the next year (see the above link). It will be a multi-crate system that require new modules. The only concern so far are the F1TDCs that will not be ready by that time. Instead we have to use the old F1TDCs with translation boards.

- Lubomir is scanning the middle chamber. The variations of the bottom/top strip ratio are as big as for the top chamber.