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(gamma,p) Run Plan

(gamma,p) Run Plan
1.267 GeV gamma d

Instructions

  1. 6 msr collimator.
  2. There should be no coincidences, set prescale 5 to 65000.
  3. There are no parasitic e-arm measurements, set PS1 = PS2 = 65000.
  4. Our interest is hadron singles. Set prescale 3 to 1, and prescale 4 so that there are 100 - 200 Hz of trigger 4.
  5. Beam current should be 25 - 30 microA.
  6. With current and time suggested, we should get about the number of good events with good FPP scattering suggested - over the entire range of photon energies - see online replay instructions.
  7. 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. Estimates will be updated later.
  8. Do not file split. Stop and restart runs at least every hour.
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 70 MeV off 25 - 30 2H 6% - - 60.52 1.216 1.5+3+9 14 h ~ 350 k
" " 1H " " " " " " 3 h ~ 8 k
" " 2H out " " " " " 5 h ~ 45 k
" " 1H " " " " " " 2 h ~ 2 k
spectrometer offset check " 12C " " " " " " ~ 10 m ~10 k
ep elastic false asym /Ac Q2=0.3486 2 1H out 29.220 1.0812 58.506 0.619 1.5 1 h 7 M
ep elastic false asym /Ac Q2=0.246887 1 1H out 23.909 1.1354 63.544 0.514 1.5 1 h 7 M
ep elastic false asym /Ac Q2=0.2205 1 1H out 22.434 1.1495 65.009 0.484 1.5 1 h 7 M
1.267 GeV gamma p

Instructions

  1. If there is spare time before the energy change, we will try to obtain 1 - 2 data points for gamma + p. Start at the forward angles - the bottom of the following table.
  2. 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 T3 and T5 as well. Current may be raised up to 30 microA if rates are < 1 kHz.
  3. Avoid file splitting if possible. Stop and restart runs when needed.
  4. Currents are for radiator in with 1H target. It is preferred to run other runs with twice the current, for half the time - but not less than ~10 minutes.
  5. The time estimates here should give reasonable data, but all of these points are unscheduled, and to be run on an if-available-time basis. The counts given are an estimated number of trigger-3 events passing non-FPP cuts. You may stop the runs early, after reaching ~1.5 - 2 times these numbers of counts.
  6. 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 5-10 minutes each, for each angle / momentum setting. These solid target runs can be done 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 75 MeV off ~10 12C out 35.59 0.929 54.593 0.6632 1.5 5 m ~10 k
" " dummy " " " " " " 10 m 30 k
" " 1H " " " " " " 20 m 700 k
" " 1H 6% " " " " " 60 m 6M
" " dummy " " " " " " 10 m 150 k
105ocm 50 MeV off ~10 dummy 6% 45.28 0.860 46.709 0.8398 1.5+3 10 m 150 k
" " 1H " " " " " " 60 m 6 M
" " 1H out " " " " " 20 m 700 k
" " dummy " " " " " " 10 m 30 k
" " 12C " " " " " " 5 m 10 k
90ocm 40 MeV off ~7 12C out 56.53 0.763 39.216 1.0063 3+6 5 m ~10 k
" " dummy " " " " " " 10 m 15 k
" " 1H " " " " " " 20 m 400 k
" " 1H 6% " " " " " 60 m 4 M
" " dummy " " " " " " 10 m 100 k
75ocm 25 MeV off ~5 dummy 6% 69.54 0.661 32.044 1.1676 1.5+3+6 10 m 100 k
" " 1H " " " " " " 60 m 4 M
" " 1H out " " " " " 20 m 400 k
" " dummy " " " " " " 10 m 20 k
" " 12C " " " " " " 5 m 10 k
60ocm 25 MeV off ~3 - 5 12C out 85.24 0.557 25.246 1.3023 1.5+6+9 5 m ~10 k
" " dummy " " " " " " 10 10 k
" " 1H " " " " " " 20 m 200 k
" " 1H 6% " " " " " 60 m 2 M
" " dummy " " " " " " 10 m 50 k
45ocm 25 MeV off 1 - 2 dummy 6% 104.02 0.467 18.704 1.4142 1.5+3+6+9 15 m 50 k
" " 1H " " " " " " 60 m 2 M
" " 1H out " " " " " 20 m 200 k
" " dummy " " " " " " 10 m 10 k
" " 12C " " " " " " 5 m ~10 k