GEM Meeting/20190329

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  • Chandan : Test Lab update slides


  • Chandan: Presented GEM DAQ deadtime measurement. With the MBTL fast readout (80MB/s) we receive about 250 Hz data trigger rate without deadtime (using 18 APVs and two MPDs). The busy signal from TIR for this setup is 3 ms. With the SST Fastreadout the busy signal became 800 us. Half of this time the MPD is processing data. So we are close to the limit. If we add SBS GEMs it will be worse!!
    • Bryan: Are we reading all the GEMs and APVs (88) uisng one crate? If yes, whatever effort we are putting to improve deadtime with 18 APVs doesn't make sense.
    • Dustin: Nilanga is interested to move his SSP system to JLab and test with our stand.
  • Dustin:Can we test the common mode correction using all 128 strips and see if the default zero-suppression (with MPD firmware) would work for cosmic or not. Though Kondo strongly disagree to use online zero-suppression with default MPD firmware.
    • Seamus: Tao will do this analysis.
  • Dustin: It would be worth to test merge the PREX and SBS system together and test before installation.
    • Seamus: Most likely that will not happen.
  • Chandan: For counting mode DAQ, which ADC would you prefer? fastbus ADC or flash ADC? - Bob prefers flash ADCs since they are simple and fast.
    • Seamus: What was used in PREX1? Dustin, would you check this?
    • Bryan: HAPEX experiment used the fastbus ADCs.


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