RescatteringPlan

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Main :: Auxiliary Measurements

  1. General: L-HRS only. Integrating mode. All data taken with target lock at nominal, raster nominal, lead target, beam current 2 uA. All parity mode runs are short (2-3 minutes) since the yield is the observable. Each setting of dp will include both the modified septum current and the nominal 333 A septum current.
  2. Nominal dp
    1. Take a run at 2 uA (detectors at production gain.)
    2. Establish Gain 1:
      • Start a parity DAQ run in production mode which will be used to help tune new detector voltages. Raise HV for main detector PMTs and At PMTs by about 250 V (factor of 2^5~32) to get back near original signal size. Compare readout voltage to original (85uA) voltage to get within a factor of two (but less than 7V readout).
    3. take another nominal spectrometer (dp=0) run at the new detector HV. (Gain 1)
  3. Change spectrometer setpoints to 1.35x nominal. Cycling the quads as usual.
    • Establish Gain 2:
      • raise MD and A_t PMT voltages by 250 more volts (do not exceed 2000V max). (Gain 2)
    • Turn on S0 and S3 voltages.
    • Turn on VDC and GEM Voltages.
    1. Start counting mode daq with T1, T2, and T3 triggers
    2. Take a short (2-3min) parity run
    3. Reduce the septum to nominal 333A. Take another short (2-3min) parity run
    4. end the counting mode run.
  4. Set next setpoint on the table, working down in dp from 1.25 through the 1.02 setpoint. For each step:
    1. Lower the magnet currents as given in the table. Raise the septum from 333 A to the table value, via 400 A to cycle.
    2. check T1 trigger rate <600kHz. If more, turn off VDC voltage. If T1 trigger rate>2MHz, also turn off scintillator HV and GEM HV.
    3. Start an counting mode run
    4. take a short (2-3 min) parity run.
      • if MD main detector voltage > 1 V, turn down to original (Gain 1) setpoint and repeat this run.
    5. Reduce the septum to nominal 333A. Take another short (2-3min) parity run
    6. end the counting mode run.
  5. Repeat the above for 1.01 and nominal setpoints, except now verify that
    • Scintillator, VDC, and GEM HV are all off. No need to run the counting DAQ
    • Main Detector HV are in the original (Gain 1) configuration. If they have not been lowered yet, be sure to have a run at the same magnet settings with both HV settings.
  6. when back to nominal, test is complete. Backout by returning MD HV to nominal.
  7. Final step is to thread the beam through the Compton. Amali asked to be called 30 minutes before this happens.
setpoint .. septum ...... Q1 ........ Q2 ........ Q3  ........  Dipole ...	
............. [A] ....... [A] ....... [A] ....... [A] ...... [GeV] ..... [A] 						
.. 1 ........ 333 ..... 118.50 .... 407.70 .... 450.76 .... 0.95285 .. 318.79
.. 1.35 ... 449.55 .... 159.98 .... 550.40 .... 608.53 .... 1.28635 .. 430.37
.. 1.25 ... 416.25 .... 148.13 .... 509.63 .... 563.45 .... 1.19106 .. 398.49
.. 1.15 ... 382.95 .... 136.28 .... 468.86 .... 518.37 .... 1.09578 .. 366.61
.. 1.10 ... 366.30 .... 130.35 .... 448.47 .... 495.84 .... 1.04814 .. 350.67
.. 1.07 ... 356.31 .... 126.80 .... 436.24 .... 482.31 .... 1.01955 .. 341.11
.. 1.04 ... 346.32 .... 123.24 .... 424.01 .... 468.79 .... 0.99096 .. 331.54
.. 1.02 ... 339.66 .... 120.87 .... 415.85 .... 459.78 .... 0.97191 .. 325.17
.. 1.01 ... 336.33 .... 119.69 .... 411.78 .... 455.27 .... 0.96238 .. 321.98
.. 1 ........ 333 ..... 118.50 .... 407.70 .... 450.76 .... 0.95285 .. 318.79