Difference between revisions of "Minutes-1-23-2014"

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# Other
 
# Other
  
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= Minutes =
 
= Minutes =
  
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Participants: Eugene, Fernando, Dave, Nick, Chris, Simon, Bill, Beni, and Lubomir.
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Participants: Eugene, Fernando, Dave, Nick, Chris, Simon, Beni, and Lubomir.
  
 
== Installation ==
 
== Installation ==
  
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- The top two quadrants were cabled (see first three pictures attached); Mike Klopf was working till his last minute at JLab, to arrange the cables nicely and uniformly (first picture). Nick is almost done with routing the second quadrant to the electronics. Casey and Tina are working now on the bottom right quadrant and have cabled already two packages (second picture).  
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- The third quadrant (down left) has been connected to the detector side (see pictures attached). To keep the cables flat on the mesh, Casey uses long zip ties; we want to make sure that at the inner side of the mesh (second picture) these ties do not touch the CDC. Starting Monday, Nick and Chris (with the help of Casey and Tina if needed) will start routing these quadrant below the platform to the electronics side. Before that, over the weekend, Beni will test the second half of the quadrant (packages 3 and 4) with the mini-DAQ.
  
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- Discussions about the routing of the LV cables. They all have to run to the left side (looking downstream) and it is not clear yet how they will be attached to the face of the magnet in their final position. Therefore, Tom prefers to disconnect them from the LV panel during insertion and then route them again to the panel. Fernando, Bill and other disagree; Beni showed on a drawing how to route the bottom half in order to avoid disconnection from the panel. Lubomir discussed if the extra length of the big bundle at the top right cable tray is enough for the FDC insertion (third picture).
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- The HV was stable at +2100V/-500V without any trips from last Thursday (1/16) till Tuesday (1/21). On Tuesday Lubomir increased it to +2200V/-500V and it was stable over the night for all the channels, except four channels where the negative HV had to be lowered by 100V to have it stable. On Wednesday morning suddenly all the positive HV channels were turned off and it is not clear how, because the lab was closed and there was nobody in the Hall. We suspect it was a power glitch, but then why the negative HV channels were still on. Beni suggested checking if the ROCs did restart at the same time which may suggest it was a power problem.  
  
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- On Monday we changed the gas to 40/60 Ar/CO2 pre-mixed bottle. The flow was initially increased from 400 to 1000 sccpm (using another mass flow controller with 6000 sccpm range and another rotameter), but at this point the bubblers stopped bubbling: the same old story and we suspect again that somehow gas channels with high impedance are created, making connection from the bubble meniscus to the air. Finally the flow was set to 800 sccpm (200 sccpm per package) so that the bubblers can work.
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- On Wednesday also the gas bottle was empty. Since there were no techs to crane a new bottle, Lubomir switched to another bottle used before which was empty by Thursday morning. It turned out that one bottle (Ar/CO2 40/60 pre-mixed) at 800 sccpm is good for four days. We decided with Tom to have always one extra, full bottle, craned on the platform, so that we can change the gas without the techs being there.
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+
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- Since Wednesday  nominal HV, +2100/-500V, has been set on all channels except one (fourth picture showing its current) with +2000/-500V and there were no trips for more than 24 hours. After the meeting that channel was also set to the nominal HV and is stable: '''all the HV channels are now operational at the nominal HV and gas mixture.'''
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== Engineering ==
 
== Engineering ==
  
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- On Wednesday morning we found the chiller off with an active alarm. It turned out that there was disruption in the chilled water supply for several minutes that most likely caused the chiller to fail. The top half of the LV channels were on at that night which increased the Fluorinert temperature to 27degC (as measured with the chiller when it was re-started). Everybody agrees that we need a hardware shutoff of the LV crate in case the chiller fails and this is urgent. Details, how to do this, were discussed at another meeting organized by Hovanes right after the FDC meeting.
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- Bill was not at the meeting
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- Even if the chiller failed due to the water disruption, Bill wanted to make sure that the chiller itself didn't contribute to that. Dave measured the temperature difference of the water in/out of the chiller and it was 31degF. According to Bull this means we have ~0.5 GPM water flow, while it is recommended to be 1.3 GPM to have smaller temperature difference. Bill is looking for a flow meter to measure the actual water flow.     
 
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- Gas system: Bill sent to Brooks one of each: mass flow controller, control unit and cable. Certainly there's a problem, most likely in the control unit. Other than that, most of the gas stuff is ready, still needs to be tested. So when we fix the flow controllers, the system can be used in principle with a manual control and using one bottle (of each, Ar and CO2) at a time. Because of the high flow we use now one bottle per week. According to Dave we expect the next gas delivery for Feb. 5 and we have a little more than one bottle in the moment. Again, we need to find a temporary solution till Feb. 5, either reducing the flow or flushing with Nitrogen and postponing the tests.
 
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- Bill talked to Jim Dahlberg, but there are no results yet from the last survey!?
 
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== Electronics ==
 
== Electronics ==
  

Revision as of 18:52, 23 January 2014

January 23, 2014 FDC meeting

Agenda

  1. Installation [1],[2] (all)
  2. Engineering (Bill)
  3. Electronics [3] (Chris, Nick)
  4. Mini-DAQ results FDC E-log (Beni)
  5. Other


Minutes

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

Installation

- The third quadrant (down left) has been connected to the detector side (see pictures attached). To keep the cables flat on the mesh, Casey uses long zip ties; we want to make sure that at the inner side of the mesh (second picture) these ties do not touch the CDC. Starting Monday, Nick and Chris (with the help of Casey and Tina if needed) will start routing these quadrant below the platform to the electronics side. Before that, over the weekend, Beni will test the second half of the quadrant (packages 3 and 4) with the mini-DAQ.

- The HV was stable at +2100V/-500V without any trips from last Thursday (1/16) till Tuesday (1/21). On Tuesday Lubomir increased it to +2200V/-500V and it was stable over the night for all the channels, except four channels where the negative HV had to be lowered by 100V to have it stable. On Wednesday morning suddenly all the positive HV channels were turned off and it is not clear how, because the lab was closed and there was nobody in the Hall. We suspect it was a power glitch, but then why the negative HV channels were still on. Beni suggested checking if the ROCs did restart at the same time which may suggest it was a power problem.

- On Wednesday also the gas bottle was empty. Since there were no techs to crane a new bottle, Lubomir switched to another bottle used before which was empty by Thursday morning. It turned out that one bottle (Ar/CO2 40/60 pre-mixed) at 800 sccpm is good for four days. We decided with Tom to have always one extra, full bottle, craned on the platform, so that we can change the gas without the techs being there.

Engineering

- Bill was not at the meeting


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