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 ps1=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.
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.
   • Exact order of runs will be posted on the whiteboard by the run coordinator.
   • Prescale the e-arm away, until it is set to positive polarity.
   • At the two largest angles we will also test with the 4-cm cell, if time is available. These tests run for about one-third the time given below for the 15-cm cell.
   • While the e-arm is being adjusted from one setting to another, prescale away the e-arm and take gamma-d data with hadron only.
   • Keep record of integrated hadron arm events on the whiteboard!
   • The e-arm times below are all in hours, for gamma+d / e+d / gamma+p(empty background) / e+p(background), and should be sufficient to give > 10 k gamma d events.

Instructions

If the gamma d data runs well and quickly, the spare time can be used either for a 1-pass gamma d measurement or for additional points of gamma p at this energy. The following plan is for the gamma p points.

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. If the current is below ~15 microA for gamma + hydrogen, the background runs may be run for about half as long at twice the current.
3. Avoid file splitting if possible. Stop and restart runs when needed.
4. 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.)
5. Comment: Pi+ background is kinematically allowed only for theta_cm > 90 deg, forward-angle data should be all protons