PVDIS 4-Pass (Resonances) Run Plan

• On Dec. 17 the accelerator will change Hall A to 4-pass, set the Wien angle such that Hall A has maximum longitudinal polarization, and measure the vertical component with one Mott measurement (to confirm it's <2%).
• Meanwhile, Hall A will 
• Survey left HRS angle (20 degrees);
• rotate both HRSs to 12.9 degrees;
• Check threshold of DAQ, plus miscellaneous work requiring (opportunitic) access.

• Kinematics: there will be two momentum settings on the left arm and one momentum setting on the right arm:
• Left arm (RES kine #3):
• P0=-4.0 GeV/c (Note: Left Q2 and Q3 can only be set to -3.66 GeV/c, use this value. Dipole and Q1 must set to -4.0 GeV/c).
• Expected electron rate: 857kHz (with Q2 and Q3 at the wrong settings there will be a 30% reduction in acceptance. So expect rate to be near 600kHz).
• Expected electron asymmetry and uncertainty: -76.7 ppm (6.5% ->7.2% with modified beam time)
• Expected pi/e ratio: <0.01
• Expected running time (calendar time): 31 hours (modified to 35 hours).
• Left arm (RES kine #4):
• P0=-3.55 GeV/c
• Expected electron rate: 566kHz
• Expected electron asymmetry and uncertainty: -69.3 ppm (6.5%)
• Expected pi/e ratio: <0.15
• Expected running time (calendar time): 57 hours (modified to 46 hours)
• Right arm (RES kine #5):
• P0=-3.10 GeV/c
• Expected electron rate: 466kHz
• Expected electron asymmetry and uncertainty: -61.7 ppm (6.5%)
• Expected pi/e ratio: <0.69
• Expected running time (calendar time): 87 hours
• Some things to pay attention to:
• Right arm will stay at kine #5 until 7am Dec. 22nd. Beam time allocation for left arm may need to be adjusted based on measured electron rates;
• Electron rate estimation here may not be reliable. Halog real rate (global electrons) from parity runs as soon as possible;
• If pion rates are higher than expected (use T1 rate - electron global rate, NOT the parity run pion global trigger rate), make a halog also.
• Swap beam IHWP halfway for each kinematics. 

• General procedure at each kinematics:
• If this is the first time putting beam on target, perform long recovery procedure until the VDC on run
• Take 500k T1 events on both arms for Q2 measurement/PID check, with a LD2 target (prescale away all other triggers);
• Move to Al dummy target, again take 500k T1 events at low current with VDC on (prescale away all other triggers);
• Take optics runs:
• Move to multi-foil carbon target, 
• Turn raster OFF
• start from 2uA, increase beam current such that T1 rates are about 1kHz.  But if this means a current of <2uA, use 2uA and set PS1 to the proper value such that accepted T1 rate is about 1kHz.
• take 250k T1 events on both arms, prescale away all other triggers;
• Do online analysis, halog plots of y_tg vs. ph_tg  and react_z for both spectrometers.
• Repeat this procedure with raster ON (same size as production)
• Put left arm sieve slits IN;
• Repeat the above procedure for multi-foil carbon target (both raster ON and OFF). Halog x-sieve vs. y_sieve for left HRS, and y_tg vs. ph_tg and react_z for both spectrometers.
• With the left arm sieve slits still IN, repeat the above procedure for LD2 target, with raster ON only. Halog x-sieve vs. y_sieve for left HRS, and y_tg vs. ph_tg and react_z for both spectrometers.
• Turn VDC OFF;
• Make sure raster is ON;
• Take a 30-minute parity run on Al dummy target using a 50uA beam, halog electron global rates;
• Move to LD2 target, start production.
• Note: the optics and Al dummy runs must be repeated when the left HRS is set to the 2nd setting (kine#4).

• Extra runs between the two left HRS kinematic settings: (the whole thing could take up to 1 shift, hence the reduced running time as shown above).
• Take optics, Q2 measurement, and productions runs at the following two magnet settings for the left HRS:
• All magnets set to -3.66 GeV/c. For currents please refer to this previous halog.
• Keep dipole and Q1 unchanged, change Q2 and Q3 settings to -3.349 GeV/c.
• The optics run procedure is the following (same as above):
• Turn VDC ON;
• Move to multi-foil carbon target, 
• Turn raster OFF
• start from 2uA, increase beam current such that T1 rates are about 1kHz.  But if this means a current of <2uA, use 2uA and set PS1 to the proper value such that accepted T1 rate is about 1kHz.
• take 250k T1 events on both arms, prescale away all other triggers;
• Repeat this procedure with raster ON (same size as production)
• Put in left arm sieve slits and repeat the measurement above for multi-foil carbon target. Halog x-sieve vs. y_sieve for left HRS, and y_tg vs. ph_tg and react_z for both spectrometers.
• The Q2 measurement is as usual: LD2 target, raster ON, VDC ON, take 2 microA (or appropriate currents to keep T1 rate below or near 1kHz). Take 250k T1 events only, prescale away all other triggers;
• Take 30 minutes of production data on LD2 target, with VDC OFF, at high current (100 microA or higher).