Difference between revisions of "Minutes-6-24-2010"

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== Production ==         
 
== Production ==         
  
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- Bill: the PR for the clean room is in place but not for the ACs. We will need the AC, the one for the whole bay area, to start moving there some stuff that doesn't require clean environment. Teresa Danforth is the person to be contacted and Glenn will help us in that.
+
- Bill: the PR for the clean room is in place but not for the ACs. We will need the AC, the one for the whole bay area, to start moving there some stuff and do some dirty work that doesn't require clean environment. Teresa Danforth is the person to be contacted and Glenn will help us in that.
  
−
- Bill: the cathode production plan is in a good shape: Fast Track procedure will be posted soon. The wire stringing planing will require more information since we have not done the stringing. Therefore, first we need to start setting up the fixtures from UVA and exercising and then clarify the procedure.
+
- Bill: the cathode production plan is in a good shape: Fast Track procedure will be posted soon. The wire production planing will require more information since we have not done the stringing. Therefore, first we need to start setting up the fixtures from UVA and exercising and then clarify the procedure.  
−
- The PR for the clean room was submitted at the end of last week. The specifications and estimate are linked above. The estimate is for $250K for the clean room, including the electrical installations, excluding the AC. According to the schedule, the installation must be completed and the room commissioned on Sep. 13 this year. The CC will take care of the network, including wireless. We will buy a color laser printer/copier/scanner for ~$700, i.e. low quality. 
+
  
−
- We discussed the place to start setting up the wire stringing before going off-site. The two options: F117 and 126 in the EEL building. Fernando is concerned there will be no space in F117, wire stringing will take 2/3 of the space there. He will prepare a floor plan for F117 for the PCB testing. Casey and others emptied a table in F117. Mark had an idea to use two such tables and the thick aluminum plate (used now for vacuuming) for the wire stringing. F117 is cleaner than 126, but we discussed if we need a clean space, since we just want to try the stringing procedure, not to make real chambers. We want to build a new design one layer prototype, but this probably can't be done in F117. Lubomir was concerned that if there's a delay moving off-site we will have to build the prototype again in 126. We will discuss this on the next meeting also when Bill is back.  
+
- We will start setting up the stringing in the tent in 126. The other option, F117, is no longer an option since there's not enough space. We decided to use the granite table in 126 for stringing. We are going to put wheels on that table. For the cathode production we will need another two granite tables. Lubomir: According to Eugene there are money for equipment so that we can buy two granite table right now. Glenn confirmed that and said that he could sign for Eugene, who is away from JLab till July 7. The plan is to put the tables directly in 727 B.C.  
  
 
== Electronics ==
 
== Electronics ==
  
−
- fADC125: Gerard is working with Bryan Moffit and wants to repeat the rate test that Bryan did with his code. Fernando suggested not to discuss this at this meeting. High signal cutoff problem: in the distribution of the maximum wire signal (page 486, FDC logbook) we see a cutoff at about 11000 fADC units (~270mV), more pronounced at higher sense wire voltages (>2225V). The fADC cutoff and, approximately, the pre-amp saturation are  at 2^14 = ~16000 and it is visible for both top and bottom strips. Fernando will investigate the wire board, since it is suppose to saturate at the same (>400mV) voltage as the cathode boards. Also we expect to see a peak (as Gerard noted) at the cutoff region, because the signals that saturates will have similar maximal values. There's no obvious peak there even at 2275V. Gerard said there's smearing by a up to 20% because of the sampling and suggested to use quadratic interpolation to find the maximum. Lubomir will do it.
+
- fADC125: Lubomir did further studies of the cutoff seen in the spectra from the wires. As suggested by Gerard on the last meeting now a quadratic interpolation is used to find the maximum from the fADC samples. At page 498 in the FDC logbook, shown are the maximum signal distributions separately for all the channels. The cutoff position varies from channel to channel somehow  and probably
  
 
- While Gerard was on the phone, Lubomir presented the results of the fADC tests. During the last (almost) week, the fADC125 was powered continuously, the temperature on the board was ~53degC always and there were no problems with the operation. The plateau, gain and strip resolution vs HV were studied (page 487 in FDC logbook) in order to choose the operational HV. Using lower threshold (~5mV at the fADC input) moves the beginning of the plateau down to ~2000-2050V (field voltage at 500V). However, the strip resolution get worse if lowering the HV. The resolution levels out above ~2225V, so probably ~2225V will be the operational HV. At this voltage some good fraction of the signals most likely saturates. Gerard asked if we are going do particle ID using dE/dX in which case probably we need even lower amplification. Beni and Simon explained that at the forward region the particles are minimum ionizing, so the signals will be similar the these with cosmics. Lubomir is concerned that now the cathode pre-amp cards are at their lowest possible setting (2.6mV/fC) for the high gain region. Fernando will look what modifications can be done so that we can lower the amplification with small steps if needed.  
 
- While Gerard was on the phone, Lubomir presented the results of the fADC tests. During the last (almost) week, the fADC125 was powered continuously, the temperature on the board was ~53degC always and there were no problems with the operation. The plateau, gain and strip resolution vs HV were studied (page 487 in FDC logbook) in order to choose the operational HV. Using lower threshold (~5mV at the fADC input) moves the beginning of the plateau down to ~2000-2050V (field voltage at 500V). However, the strip resolution get worse if lowering the HV. The resolution levels out above ~2225V, so probably ~2225V will be the operational HV. At this voltage some good fraction of the signals most likely saturates. Gerard asked if we are going do particle ID using dE/dX in which case probably we need even lower amplification. Beni and Simon explained that at the forward region the particles are minimum ionizing, so the signals will be similar the these with cosmics. Lubomir is concerned that now the cathode pre-amp cards are at their lowest possible setting (2.6mV/fC) for the high gain region. Fernando will look what modifications can be done so that we can lower the amplification with small steps if needed.  

Revision as of 15:41, 25 June 2010

June 24, 2010 FDC meeting

Tentative Agenda

  1. Production
  2. Electronics
    • fADC125 status (Gerard, Fernando)
    • ground modifications
  3. Cathode redesign: finalizing (Roger, Bill)
  4. Full-scale prototype tests
  5. Other


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