Difference between revisions of "Minutes-8-5-2010"

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#* 727 B.C. status
 
#* 727 B.C. status
 
#* equipment/materials needed for the production [http://www.jlab.org/Hall-D/detector/fdc/production/materials.txt Casey's list]
 
#* equipment/materials needed for the production [http://www.jlab.org/Hall-D/detector/fdc/production/materials.txt Casey's list]
# Electronics: update (Fernando)
+
# Electronics: update (Fernando) [https://halldweb.jlab.org/DocDB/0015/001567/001/FDC%20PCB%20QA.pdf doc1567]
 
# Engineering
 
# Engineering
 
#* Cathode foil: flex soldering/gluing, procurement status (Roger) [[http://solutions.3m.com/wps/portal/3M/en_US/electronics/home/productsandservices/products/ProductNavigator/TapeAdhesives/?PC_7_RJH9U5230GE3E02LECIE20KHO6_nid=R1DP54D6BCbeG7W0C8BLTFgl 3M conductive film]]
 
#* Cathode foil: flex soldering/gluing, procurement status (Roger) [[http://solutions.3m.com/wps/portal/3M/en_US/electronics/home/productsandservices/products/ProductNavigator/TapeAdhesives/?PC_7_RJH9U5230GE3E02LECIE20KHO6_nid=R1DP54D6BCbeG7W0C8BLTFgl 3M conductive film]]
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#* cosmic test update (Beni)  
 
#* cosmic test update (Beni)  
 
#* wire resolution results
 
#* wire resolution results
# Other
+
# Other: [http://www.jlab.org/~pentchev/FDC/LPentchev_CAARI2010.docx FDC paper]
  
<!--
 
  
 
= Minutes =
 
= Minutes =
Participants: Eugene, Fernando, Glenn, Roger, Casey, Mark, Bill, Beni, Simon, Vladimir Nelyubin, and Lubomir.
+
Participants: Eugene, Fernando, David, Glenn, Bill, Roger, Casey, Mark, Chuck, Beni, Simon, and Lubomir.
 
+
  
 +
We welcomed the new FDC construction coordinator, David Butler.
  
 
== Production ==
 
== Production ==
  
- No news about Blue Crab.  
+
- Bill: there will be a delay with the clean room construction, because some of the specifications (like +/-2% humidity control) were not realistic, which delays the bidding process. Eugene: the leading time is about 3 months, so expect it ready by December, although they will try to speed up the construction.  
  
- There will be a meeting, end of next week, including Tim and Tom about the FDC production and the tech labor. Bill prefers to start the production with 5 techs and then based on the performance, to adjust this number to have the chambers produced in time. Eugene suggested 20% contingency. According to the baseline the production should start in November 2010 and finish in October 2012, including the testing. The installation starts in January 2013.
+
- Casey created a list of equipment and materials needed for the production. Everybody is encouraged to look at the link above. We discussed what type of microscope we need for the wire and flex soldering. Casey who is expected to be the main user, wanted to have bigger working distance than the new Fernando's microscope. It will be nice also to have a fast camera to work in real time just looking at the screen.  
  
 
== Electronics ==
 
== Electronics ==
  
- Fernando: received the first article PCBs but has not looked yet; still waiting for F117 to be ready for use. Mark is helping in making space there. Fernando will test the boards by himself, including mechanical tests. If they pass, CEM will continue with the full production, then all the boards together will be send for stuffing.  
+
- Fernando reported on the acceptance test of the first article PCBs (see attached document). Overall the quality was good, the PDBs are accepted and the production should continue as scheduled. There were few exceptions, some of them minor, some easily fixable: on some of the boards the vias were not filled as required. One important issue was discussed: the material used in the boards is FR-4, but we required g10. We have to find out what's wrong with FR4 (water absorption, bromine content?) and see if we really need g10. Fernando will continue with electrical tests. After the meeting we went to F117 where Fernando showed the boards, their quality is certainly higher than of the boards used in the full-scale prototype.
  
- two vendors responded for the 18m cable assembly. If they both meet the requirements, the lower price criteria will apply. Bill was concerned about the length of the part of the cable on which the ground is removed. Fernando: that length is equal to the distance from the front of the magnet to the FDC package, there's no big change in the diameter of the cable, so it shouldn't be a problem to feed the cables between CDC and BCAL if taking the FDC upstreams for maintenance. No news about fADC.  
+
- One of the two cable companies was awarded, the price is 20% lower.
  
 
== Engineering ==
 
== Engineering ==
  
- Cathode foils: we discussed Roger's PR for the cathode foils. Next week he will generate a sole-source PR. One set of panels will be packed in one tube. We discussed some procurement related issues, like small businesses, priority. The cathode foil PR will have 1st priority, Bill will change the priorities for the wire and cathode frames from 3 to 1.
+
- Cathode foils: the PR submitted, waiting for signatures. Roger discussed with Allflex people the grounding of the flexes that is done by vias which can be very costly. Different ideas were exchange: to make the flex longer on the sides and fold it, to use double-sided flexes and connect the two sides with conductive glue at the periphery of the flexes. Roger got also important information from Allflex: conductive film that conducts in one direction only (3M company) can be used instead of the cathode soldering. Has to be heated to 400 deg F, but Bill says this should be OK. Bill will ask for samples and we will start playing as soon as we have the first article cathode foils.
  
- Wire stringing: Bill had concerns about the precision of the position system at UVA (see pictures attached above). Vladimir explained how the system works and answered Bill's questions. They have measured the resolution to be 25 microns. Vladimir thinks it can be improved (as Bill suggested), but it is good enough for our purposes. Bill was concerned also about the space the system will occupy and that we have to move it around the table. Different options were discussed: moving the table, using two cameras. Bill: if he would start from scratch, he would build different system with better resolution. The plan is to get the system at JLab, check the resolution and then to decide what to do. Vladimir also explained how the tension measurement works: apply sine voltage on an electrode on the top of the chamber and pick up the signal from another electrode on the top of the wire to look for resonance.  
+
- The mylar windows of the FDC packages (2 per package) have to be thicker, as Bill requested. We agreed that their thickness can be increased from 1/2 mil to 1 or 2mil which is a small change compared to the target thickness.
  
- The next step withe the cathode frame prototyping would be to glue the flaps on the back of the frame and then to glue the mylar foil which is now glued to the transfer ring.  
+
- Wire stringing: the strongbacks from UVA have arrived. Bill also will order the pieces needed to attach the pin-rails to the granite table.  
  
 
== Full-scale prototype test  ==
 
== Full-scale prototype test  ==
  
- Lubomir studied with Garfield the drift velocities and the magnetic field effects for different gas mixtures: 90/10, 70/30 and 40/60% Ar/CO2 (see pictures attached). 90/10 is the best from velocity point of view, since it is almost constant with respect to the electric field, while 40/60 exhibits strong dependence. As for the Lorentz angle, it is a factor of two bigger for 90/10 than for 40/60 and hence the deflection of the trajectories due the magnetic field will be bigger. The effect of these two factors on the drift time resolution are demonstrated at page 507 of the FDC logbook: plotted are the drift time spectra for the two gas mixtures with and without magnetic field. The resolutions are better for 90/10 even the increase of the drift time is much bigger for 90/10 compared to 40/60. Simon: we should consider also the shift in the position along the wire. Eugene: we might benefit from bigger shifts when solving left/right ambiguity. There's also the question of stability of operation with less quenching. Beni will switch to 90/10 mixture at the end of the week. Lubomir also studied the effect of the field wire voltage. The best drift time resolution is achieved with the field wires at zero voltage, in which case there are no filed lines between the field wires and the cathode and the field is more cylindrically symmetric which results in better resolution.  
+
- Beni connected the new oxygen sensor. The instructions how to read it in case of different gases are posted at the FDC logbook page 511. Indeed, the measurements confirmed that we have oxygen contamination of the order of 0.1% that explains the mean charge vs drift time dependence.  
  
- Beni is working with the bottom layer: same high efficiency, hasn't studied yet the top/bottom asymmetry we observed for the top and middle layers. Beni si varying now the field voltage and after that he will switch to 90/10 gas mixture.
+
- Now we have an estimation for the wire resolution, using two chamber layers with parallel wires and external tracking with the IU chambers. Beni showed several plots from the FDC logbook explaining the procedure. The mean resolution is about 200 microns and varies with the distance to the wire. There's a systematic deviation from the expected by the external tracking angle, that can be corrected for, but has to be understood.
 
+
- Beni set up the oxygen measuring system, first using the old oxygen sensor. The readings were controversial and now he is acquiring the parts needed to connect the new oxygen sensor.
+
  
 
== Other ==
 
== Other ==
  
At the end Vladimir suggested to use the milling machine system (with 1mil=25 microns accuracy) in the machine shop to check the UVA position measuring system.
+
Lubomir will have a talk at a conference (CAARI2010) next week, the contributed paper is linked above; comments and remarks are welcome. Whether there will be a FDC meeting next week will be decided later next week.
 
+
-->
+

Latest revision as of 12:39, 14 March 2017

August 5, 2010 FDC meeting

Tentative Agenda

  1. Production
    • 727 B.C. status
    • equipment/materials needed for the production Casey's list
  2. Electronics: update (Fernando) doc1567
  3. Engineering
    • Cathode foil: flex soldering/gluing, procurement status (Roger) [3M conductive film]
    • Mylar window thickness
    • Wire stringing update (Bill)
  4. Full-scale prototype tests [FDC Log Book, pages 509-512]
    • oxygen contamination measurements (Beni)
    • cosmic test update (Beni)
    • wire resolution results
  5. Other: FDC paper


Minutes

Participants: Eugene, Fernando, David, Glenn, Bill, Roger, Casey, Mark, Chuck, Beni, Simon, and Lubomir.

We welcomed the new FDC construction coordinator, David Butler.

Production

- Bill: there will be a delay with the clean room construction, because some of the specifications (like +/-2% humidity control) were not realistic, which delays the bidding process. Eugene: the leading time is about 3 months, so expect it ready by December, although they will try to speed up the construction.

- Casey created a list of equipment and materials needed for the production. Everybody is encouraged to look at the link above. We discussed what type of microscope we need for the wire and flex soldering. Casey who is expected to be the main user, wanted to have bigger working distance than the new Fernando's microscope. It will be nice also to have a fast camera to work in real time just looking at the screen.

Electronics

- Fernando reported on the acceptance test of the first article PCBs (see attached document). Overall the quality was good, the PDBs are accepted and the production should continue as scheduled. There were few exceptions, some of them minor, some easily fixable: on some of the boards the vias were not filled as required. One important issue was discussed: the material used in the boards is FR-4, but we required g10. We have to find out what's wrong with FR4 (water absorption, bromine content?) and see if we really need g10. Fernando will continue with electrical tests. After the meeting we went to F117 where Fernando showed the boards, their quality is certainly higher than of the boards used in the full-scale prototype.

- One of the two cable companies was awarded, the price is 20% lower.

Engineering

- Cathode foils: the PR submitted, waiting for signatures. Roger discussed with Allflex people the grounding of the flexes that is done by vias which can be very costly. Different ideas were exchange: to make the flex longer on the sides and fold it, to use double-sided flexes and connect the two sides with conductive glue at the periphery of the flexes. Roger got also important information from Allflex: conductive film that conducts in one direction only (3M company) can be used instead of the cathode soldering. Has to be heated to 400 deg F, but Bill says this should be OK. Bill will ask for samples and we will start playing as soon as we have the first article cathode foils.

- The mylar windows of the FDC packages (2 per package) have to be thicker, as Bill requested. We agreed that their thickness can be increased from 1/2 mil to 1 or 2mil which is a small change compared to the target thickness.

- Wire stringing: the strongbacks from UVA have arrived. Bill also will order the pieces needed to attach the pin-rails to the granite table.

Full-scale prototype test

- Beni connected the new oxygen sensor. The instructions how to read it in case of different gases are posted at the FDC logbook page 511. Indeed, the measurements confirmed that we have oxygen contamination of the order of 0.1% that explains the mean charge vs drift time dependence.

- Now we have an estimation for the wire resolution, using two chamber layers with parallel wires and external tracking with the IU chambers. Beni showed several plots from the FDC logbook explaining the procedure. The mean resolution is about 200 microns and varies with the distance to the wire. There's a systematic deviation from the expected by the external tracking angle, that can be corrected for, but has to be understood.

Other

Lubomir will have a talk at a conference (CAARI2010) next week, the contributed paper is linked above; comments and remarks are welcome. Whether there will be a FDC meeting next week will be decided later next week.