Difference between revisions of "Minutes-12-5-2013"

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= Agenda =
 
= Agenda =
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# Installation status ,[http://www.jlab.org/Hall-D/detector/fdc/installation/FDCin_upstream.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCpulling_in.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCin_downstream.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCin_downstrea2.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDC_installation.pdf] (all)
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# Installation status [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCin_upstream.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCpulling_in.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDCin_downstrea2.JPG], [http://www.jlab.org/Hall-D/detector/fdc/installation/FDC_installation.pdf] (all)
 
# Engineering (Bill)
 
# Engineering (Bill)
 
#* FDC survey [http://www.jlab.org/Hall-D/detector/fdc/installation/DT_D1519.xlsx]
 
#* FDC survey [http://www.jlab.org/Hall-D/detector/fdc/installation/DT_D1519.xlsx]
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# Electronics (Chris, Nick)
 
# Electronics (Chris, Nick)
 
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# Mini-DAQ [https://halldweb1.jlab.org/wiki/index.php/First_Tests_in_Hall-D] (Beni)
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# Mini-DAQ [https://halldweb.jlab.org/wiki/index.php/First_Tests_in_Hall-D] (Beni)
 
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# Other
 
# Other
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= Minutes =
 
= Minutes =
  
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Participants: Bill, Dave, Nick, Chris, Simon, Vlad, Beni, Elton, Hovanes (for the LV control discussions) and Lubomir.
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Participants: Bill, Dave, Nick, Chris, Simon, Beni, and Lubomir.
  
 
== Installation ==
 
== Installation ==
  
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- Dave: right now techs are working on the mesh, it will be finished by the end of the day or tomorrow. Tom prefers only after that the FDC to be moved on the platform (today or tomorrow morning). In the mean time Tom and Dave tested the cooling system for leakage with He at 10-15 psi using the big testing unit used for the magnet. A leak was found in the connection of one of the manifolds and Casey fixed it. Dave made the houses and the fittings needed to connect the FDC to the chiller once it is on the platform. As of yesterday we have also chilled water and the connections to the chiller are ready.
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- The work on the mesh was finished just before Thanksgiving. LV cabling: over the weekend Vlad connected 11 out of 14 bundles for the cathodes (each 8 cables) at the detector side. The three remaining bundles are at the bottom of the FDC; in addition 24 cables for the anode LV and threshold have to be connected.  
  
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- We discussed details how to connect/bundle/route the LV cables. The cables will be laying on the floor all over the platform for some time and we want to make sure the cables and especially the connectors are at a safe place. Most likely we have to run the individual cables around the pair spectrometer magnet (these are 18m long cables) and then bundle them in groups of 8 or 9. The exact procedure will be clear once we start cabling. We should have then the bundles routed so that they don't interfere with the signal cables. We want to use regular cable ties at least close to the connectors (for strain relief), but then along the mesh we cab use Velcro ties (Nick has now narrower ties with bigger friction).
+
- On Monday there was an attempt to insert the FDC into the bore but it was difficult to move it. After some fixes done by Bill and some improvements, there was another attempt to insert it: this time the reflector holders at the top side were very close to BCAL, one of them broke at the epoxy after hitting a screw from a BCAL electronics box. The holder was re-glued and the top of the holders only at the top FDC side were filed taking out several mm. Finally on Tuesday the FDC together with the mesh were inserted in the magnet and surveyed there (see pictures above). 
 +
 
 +
- Today the FDC was pulled/pushed out of the magnet and placed in a position for cabling. Before that openings in the platform were made to get access to the bottom side. Also scaffolds were install at the floor below the FDC and the mesh. Lubomir started working on the LV cables at the bottom side. The plan is to finish connecting the LV cables to the detector by Monday. Then we will connect them temporary to the LV panels and start testing. For that we will need the cooling system and Bill and Dave are going to connect it tomorrow.
  
 
== Engineering ==
 
== Engineering ==
  
−
- The raw data from the last survey is now available (attached above, all the numbers are in meters). At a first look the thicknesses of the packages are OK, +/- 0.3mm from the nominal, but this requires more studies. The main question was if the prisms can be used to measure the z positions with a few hundred microns resolution, but the data we have are not enough to make a conclusion.  Still one can see that the z positions of the prisms at one package vary by up to 6mm but Bill says this is possible given the way the prisms are glued to the gussets. The distances between the packages from the SMR and from the prism measurements are similar (up to few mm) for the package #1-#2 and #2-#3. There's about 4cm difference for the distance between #3 and #4, but there one has to take into account the SMR holder sizes. Certainly all this require careful analysis.
+
- Bill: there are discrepancies in the survey results and Bill is going to work on the survey data; we are also waiting for the results of the survey done on Tuesday. Since the reflector holders only at one side hit the BCAL it means FDC is not on the same axis (by ~5 mm?), hopefully it is closer to the beam axis.
  
−
- Important is that the prisms were survey from a big distance of 6-8 m, chosen by the survey people to have very similar angles w.r.t. prism surfaces. However we will not have that space between the FDC in the magnet and the FCAL in the current position. Bill will talk to the survey group to find if they have estimated the effect of distance to the targets. After the meeting Bill talked to Jim Dahlberg: the prisms are accurate at 100 micron level if viewed at +/-5cm transversely at 3m from the target; at +/- 10cm the accuracy is 170 microns.  
+
- We discussed how to scan the positions of the strips on the spare cathode. Lubomir obtained best resolution from the full package tests when decreasing the wire pitch by 10 microns which is unrealistic (1mm over the whole length!). We suspect it is the strip pitch that has to be modified and that's why this scan is very important. We want to measure the strip pitch along several lines (7 or 9) perpendicular to the strips. Bill will talk to the survey people about this.
  
−
- Once the mesh is installed Bill wants to make sure CDC will fit. A wooden disk with bearings inserted in the rails will be used for that. The disk will be inside the mesh while cabling the FDC so that we can do checks from time to time. Bill thinks that at least initially the cables shouldn't be connected to the mesh very tightly so that we have the freedom to shape the mesh if it is not cylindrical.
+
== Other ==
  
−
== Electronics ==
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- No meeting next week: Holiday party
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+
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- We have everything needed to start the cabling. According to Nick with the temporary 120V/20A power we can't have more than 4 LV modules in the crate, so we will be doing the LV tests in groups of several modules.
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+
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== Mini-DAQ ==
+
−
 
+
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- Beni installed the computer "joebesser" on the platform close to the north racks. Hovanes set-up and tested the  LV control system that can be used from "joebesser" under "halld" account. Since we have to change the LV module configuration and this requires ioc reboot, Hovanes gave us (at least temporary) privileges to do this.
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Latest revision as of 23:53, 31 March 2015

December 5, 2013 FDC meeting

Agenda

  1. Installation status [1], [2], [3], [4] (all)
  2. Engineering (Bill)
    • FDC survey [5]
    • Cathode scan [6]
  3. Electronics (Chris, Nick)
  4. Other

Minutes

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

Installation

- The work on the mesh was finished just before Thanksgiving. LV cabling: over the weekend Vlad connected 11 out of 14 bundles for the cathodes (each 8 cables) at the detector side. The three remaining bundles are at the bottom of the FDC; in addition 24 cables for the anode LV and threshold have to be connected.

- On Monday there was an attempt to insert the FDC into the bore but it was difficult to move it. After some fixes done by Bill and some improvements, there was another attempt to insert it: this time the reflector holders at the top side were very close to BCAL, one of them broke at the epoxy after hitting a screw from a BCAL electronics box. The holder was re-glued and the top of the holders only at the top FDC side were filed taking out several mm. Finally on Tuesday the FDC together with the mesh were inserted in the magnet and surveyed there (see pictures above).

- Today the FDC was pulled/pushed out of the magnet and placed in a position for cabling. Before that openings in the platform were made to get access to the bottom side. Also scaffolds were install at the floor below the FDC and the mesh. Lubomir started working on the LV cables at the bottom side. The plan is to finish connecting the LV cables to the detector by Monday. Then we will connect them temporary to the LV panels and start testing. For that we will need the cooling system and Bill and Dave are going to connect it tomorrow.

Engineering

- Bill: there are discrepancies in the survey results and Bill is going to work on the survey data; we are also waiting for the results of the survey done on Tuesday. Since the reflector holders only at one side hit the BCAL it means FDC is not on the same axis (by ~5 mm?), hopefully it is closer to the beam axis.

- We discussed how to scan the positions of the strips on the spare cathode. Lubomir obtained best resolution from the full package tests when decreasing the wire pitch by 10 microns which is unrealistic (1mm over the whole length!). We suspect it is the strip pitch that has to be modified and that's why this scan is very important. We want to measure the strip pitch along several lines (7 or 9) perpendicular to the strips. Bill will talk to the survey people about this.

Other

- No meeting next week: Holiday party

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