E01-017(g6c) Running Condition

• Trigger

  ASYNC TRG

  • MOR

  The photon range of interest for E01-017 is for photon energy greater than 4.8 GeV. We will thus keep only the first 12 T-counters (up to 0.84xE_beam) of the tagger into the MOR. All others will be disconnected from the MOR (and need to be terminated with 50 Ohms). We will nevertheless keep HV on all T's, to have them in the scalers (and read all E/T in the DAQ). (tagging range: 0.84 to 0.95 of E. Running a 5.734 GeV electron beam will produce a photon beam in the energy range [4.8, 5.45] GeV. No prescale will be used.

  Two ASYNC will be set:

  ASYNC 1 ------> MOR(1-12)*ST(2/3) initial values MOR 200MeV (thr.) 10ns (width) ST 200MeV (thr.) 15ns (width)

  ASYNC 2 ------> MOR(1-12)*ST(1/3)

  they differ only on the ST coinc.The production trigger will be determined on commissioning. Initial delays: MOR (2ns) and ST(14ns) from last run.
  Cable lengths from the Tagger electronics region to the forward carriage, measured by pulsor(ns):
  [1-61] MOR: 105
  [1-12] MOR: 102
  [ST 1/3]: 109
  [ST 2/3]: 113.2
  
  • CLAS-DAQ L1 Trigger

  g6c production trigger (at high current) two_sectors_async(1or2) -> bit 1 , no prescale. There are two files from last g6b run

  g6_TWOSECTOR_ASYNC2

  g6_TWOSECTOR_60_ASYNC2

  both make coincidence with async2. the sencond uses only TOF paddles in the 60 degree forward direction (without 6 last TOF counters) there are also g6_open (unbias)

• Radiator
  • production

    2x10^-4 or 3x10^-4

  • normalization

    10^-5

• Torus Field

  1/2 B_max

  I_torus= 1688 A

• Collimator

2.8 mm

• Rate Consideration

  WE WILL STRIVE FOR THE MAX PHOTON FLUX

  The desired photon flux is of 1.5-2.0x10^7 ph/sec in the tagging range [0.85,0.95]*5.734 GeV. This requires a 60nA electron beam flux. We will run at the max DAQ rate (4000Hz) and dead times of about 80%

  Level 2: Need to load right configuration. We are requiring any two sectors. We will need to have a Level 2 that provide "one DC track" in any of two (or some other combination: talk to Dave or Elliot)

• Normalization

  Same as g8 procedureBernhard Mecking's notes

• Target

  LH₂ target, 18x3 cm cylindrical cell (same as g8), pulled back upstram by 100cm from the center of CLAS.

• Start Counter

  The main high voltage values (V):

  
  Sector1: -1980
  Sector2: -1960
  Sector3: -1910
  Sector4: -1900
  Sector5: -1850
  Sector6: -1975
  
  

  The -800V booster voltages are also Connected. Current booster voltage settings (V):

  
  Sector1: -750
  Sector2: -750
  Sector3: -750
  Sector4: -750
  Sector5: -750
  Sector6: -750
  
  

  The trigger electronics:

  The analog signals from the two sides of each pair are summed using a Phillips 740 Quad Linear FIFO module. The summed output is discriminated using a Phillips 730 module and the 3 resulting signals(one for each pair) are OR-ed together (2 out of 3) to provide the start counter trigger signal. Pair 3 is configured differently from the other pairs: we are using the out-bar of the FIFO because the incoming pulses are positive polarity.
  
  

  The trigger thresholds (mV):

  
  Pair1: (sectors 1&2): LLT=65, ULT=130
  Pair2: (sectors 3&4): LLT=65, ULT=130
  Pair3: (sectors 5&6): LLT=20, ULT=40
  
  The trigger discriminators are Phillips 730 Tri-Mode discriminatiors, which are operating in the ARC(Amplitude Risetime Compensation) mode with a 4 ns additional internal delay. The Threshods for pair 3 are different because we are discrimination the sum of two dynode signals, whereas the bases for the other 2 pairs are configured such that the trigger and the data signals are the same.

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