Event size estimation

 Estimation of FGT event size for pp events @ 500 GeV is 20KB/eve after ZS, physics event will use 80% of this volume.

  1. empty event: 3.7KB Concluding: for 3-sample empty events we need 3.7 KB   300*(2+2+2+2)+30000*(2+2+2+2)/200+100=3700 bytes.
    • total # of channels: 128 ch X 10 APV x4 quad x 6 disks = 30K channels.
    • zero suppression (ZS) is  aiming to keep 1/100 of ADC channels, set to about 3 sigma above ped. Needs testing with data & real electronics, time stability, beam halo, AC-noise . Perhaps we can ZS more.
    • with ZS we need 4 bytes per hit:
      • we need 2 bytes (log2(30k)=14.9) for channel ID
      • ADC value needs up to 12 bits, assume we write it as 16 with 4 bits unused, as with ESMD
    • we may want to keep ADC for 3 time slots per event (using 25 ns integration window) increasing hit size to 8=4+2+2 bytes.
    • it is enough to keep 1/1000 events w/o ZS for monitoring of pedestals
    • event header needs 100 bytes

    2.  

  2. pp data taking
    • assume every track fires 5 strips (will be more at Rin and less at Rout due to varied width of phi strips)
    • trigger event is always embedded in 6 minBias pileup events 
      • at top RHIC luminosity we have 1.5 minB interactions per bXing
      • 300 nsec of analog pulse --> need to account for 4 pre-trigger bXings --> 4x1.5=6 minB eve/trig eve 
      • based on OLD Pythia simulations (obsolete disk size & location) @ 500 GeV one expects 1 track per quadrant per minB event.
      • conclusion: 1440 ADCs will fire due to underlying pileup event   (4 tracks * 6 disks * 2 planes *6 events *5 strips= 1440 

       

    • W-trigger will fire mostly on jets, ASSUME HT consumes lot of jet energy and there is 10 charged (low pT) tracks in such jet. 10 tracks * 6 disks * 2 planes * 5 strips= 600 ADCs. 
      • total physics event content will be 2000 ADC channels. This requires 16KB (2000 *8 bytes)

    3.  

  3.  Heavy Ion even - no study was performed so far.