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(gamma,p) Run Plan

(gamma,p) Run Plan
0.856 GeV systematics
  1. Nilanga Liyanage: optics
  2. call in Mark Stevens for polarity change
  3. During spectrometer ramp time before/after change...
    1. arc energy measurement
    2. BCM calibration
  4. Moller polarization measurement: may fit in earlier if convenient
  5. radiator recheck - decide foil to use for data
0.856 GeV gamma p

Instructions

  1. Estimated currents result in ~2 kHz DAQ rate. We are most interested in T3 and T5 triggers. Prescale T1, T2, and T4 triggers to ~ 100 Hz; these give us information on efficiencies. If dead time / trigger rates are high, lower currents (not below 1 microA) and / or prescale data. Current may be raised if rates are < 1 kHz.
  2. With current and time suggested, we should get about the number of good events with good FPP scattering suggested - see online replay instructions.
  3. Avoid file splitting if possible. Stop and restart runs when needed.
  4. The time estimate is based on scheduled time with 50% availability. Do not significantly shorten runs if count rate is larger than expected. If count rate is below estimates, run up to about two times longer, unless we are behind schedule.
  5. Radiator-out hydrogen runs should be about 60% as long as radiator-in runs, except all empty target runs should be for 10 minutes of data - do not worry about adjusting their time. 12C measurements are to determine y-target offsets, and should be run for 10 minutes each.
  6. For each angle / momentum setting, take a measurement on 12C solid target for ~10 minutes while the magnets are settling. This should be done with raster off. (This is used to check spectrometer offsets, which are not now regularly measured.)
  7. Comment: Pi+ background is kinematically allowed only for thetacm > 90 deg, forward-angle data should be all protons
Task Ie  Target  Radiator  th-e  p-e  th-h  p-h  FPP  Time Counts
(uA)  (%)  deg  GeV  deg  GeV  door  h or m good event+good FPP
120ocm 85 MeV off 2 12C out 42.29 0.595 55.77 0.484 1.5 5 ~10 k
" " dummy " " " " " " " -
" " 1H " " " " " " 30 m -
" " 1H 4% " " " " " 60 m -
" " dummy " " " " " " 5 m -
120ocm 15 MeV off 2 dummy 4% 40.69 0.652 55.77 0.514 1.5 5 -
" " 1H " " " " " " 60 m -
" " 1H out " " " " " 30 m -
" " dummy " " " " " " 5 m -
" " 12C " " " " " " 5 m -
105ocm 85 MeV off 2 12C out 53.32 0.556 48.24 0.598 1.5 5 m ~10 k
" " dummy " " " " " " " -
" " 1H " " " " " " 30 m -
" " 1H 4% " " " " " 60 m -
" " dummy " " " " " " 5 m -
105ocm 15 MeV off 2 dummy 4% 51.43 0.606 48.24 0.635 1.5 5 -
" " 1H " " " " " " 60 m -
" " 1H out " " " " " 30 m -
" " dummy " " " " " " 5 m -
" " 12C " " " " " " 5 m -
90ocm 25 MeV off 2 12C out 63.88 0.542 40.87 0.744 3 5 m ~10 k
" " dummy " " " " " " " -
" " 1H " " " " " " 30 m -
" " 1H 4% " " " " " 60 m -
" " dummy " " " " " " 5 m -
75ocm 25 MeV off 2 dummy 4% 77.76 0.481 33.69 0.847 1.5+3 5 -
" " 1H " " " " " " 60 m -
" " 1H out " " " " " 30 m -
" " dummy " " " " " " 5 m -
" " 12C " " " " " " 5 m -
60ocm 25 MeV off 2 12C out 93.69 0.422 26.70 0.938 6 5 m ~10 k
" " dummy " " " " " " " -
" " 1H " " " " " " 30 m -
" " 1H 4% " " " " " 60 m -
" " dummy " " " " " " 5 m -
45ocm 25 MeV off 2 dummy 4% 111.99 0.371 19.87 1.012 3+6 5 m -
" " 1H " " " " " " 60 m -
" " 1H out " " " " " 30 m -
" " dummy " " " " " " 5 m -
" " 12C " " " " " " 5 m -
0.856 GeV gamma d

Instructions

  1. Do this only at the end, if all runs well.
  2. We are only interested in hadron arm singles triggers, T3 and same T4. Prescale away T1, T2, and T5. Prescale T4 to ~ 100 Hz.
  3. Run deuteron photodisintegration at the largest current that keeps dead time small, < 10 %, but do not run above 30 microA.
  4. With current and time suggested, we should get about the number of good events with good FPP scattering suggested - see online replay instructions.
  5. The time estimate is based on scheduled time with 50% availability. Do not significantly shorten runs if count rate is larger than expected. If count rate is below estimates, run up to about two times longer, unless we are behind schedule.
  6. Do not file split. Stop and restart runs every hour.
  7. Do 40-MeV-offset setting first, and 95-MeV-offset setting if time is available.
Task Ie  Target  Radiator  th-e  p-e  th-h  p-h  FPP  Time Counts
(uA)  (%)  deg GeV deg  GeV door  h or m good event+good FPP
90ocm 40 MeV offset 30 D in - - 65.382 0.961 1.5 + 6 2 h ~20 k
" " H in - - " " " 10 m ?
" " H out - - " " " 10 m ?
spectrometer offset check (raster off!) 5 12C out - - " " " 10 m ~1 k
" 30 D out - - " " " 1.2 h ~4 k
90ocm 95 MeV offset 30 D in - - 65.382 0.928 1.5 + 6 4 h ~40 k
" " H in - - " " " 10 m ?
" " H out - - " " " 10 m ?
spectrometer offset check (raster off!) 5 12C out - - " " " 10 m ~1 k
" 30 D out - - " " " 2.4 h ~8 k