Instructions

1. There should be no coincidences, set prescale 5 to 65000.
2. The main experiment is hadron singles. Set prescale 3 to 1, and prescale 4 so that there are 100 Hz of trigger 4.
3. For the parasitic measurements with the e-arm, we want to set prescales so that there is not much dead time, < 10%. Setting ps=1 and ps2 for 100 Hz of T2 should work, but increase these if dead time exceeds 10%.
4. Beam current should be 25 - 30 microA, but decrease it if dead times from the hadron arm alone are large.
5. With current and time suggested, we should get about the number of good events with good FPP scattering suggested - see online replay instructions.
6. 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.
7. Do not file split. Stop and restart runs every hour.
8. After the e-arm polarity change to +, start running according to the time needs of the parasitic measurements.
   • Prescale the e-arm away, until it is set to positive polarity.
   • These measurements require about 10 minutes of gamma p, 2 hours gamma d, 1 hour of e d, 10 minutes of e p, and 10 minutes of e + C (raster off, i ~ 15 microA).
   • At the two largest angles we will also test with the 4 cm cell, if time is available.
   • While the e-arm is being adjusted from one setting to another, set for gamma - d, and take data with the e-arm prescaled away.

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 theta_cm > 90 deg, forward-angle data should be all protons