GEM Meeting/20190405

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Logistic information

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  • Siyu: PRex UVa GEM updateslides
  • Chandan: Test Lab update slides


  • Chandan: The Fastbus ADC (LeCroy 1881M) is good for Q2 measurement - based on specification on datasheet
  • Chandan: One of the PREX GEM detector has a board problem. It instroduces small (~5 pF) in series with the foil capacitance. Avoided by connecting two segments of the same foil and finally connected to the voltage divider using the existing good connection. The same detector has some wired pesdestal problem. It looks intrinsic to the detector.
  • Chandan: There are problem with the ISU daq3 computer. It cannot handle data rate more than 20 MB/s. Using different coda server, the present DAQ (18 APVs) can reach upto 1.3 kHz trigger rate without any dead time. Based on the tr busy signal, MPD data readout time and network cable transer rate, the maximum trigger rate for 84 APVs is estimated and that value is ~ 800 Hz (assuming using two crates with42 APV cards in each crate).
    • Seamus: Nilanga said in some HallA experiment they achieved 500 Hz trigger rate using 110 APV cards. We have to confirm how many crates they gave used and how many smaples/ strip they read during the experiment.
  • Seamus: Retrieve old PREX counting mode codes and working on that.
  • Siyu: Gave a update for SBS-GEM requirement.
  • Seamus: Tao has figured out the SLAC data mismatch problem.
    • Dustin:There were problem with cleaning buffer for every run. That has been taken care during data aquisition using plastic trigger. Probably we could modify the read-out lsit to solve the problem.


Dustin, Seamus, Ryan, Tao, Cameron, Siyu, Bryan, Chandan