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Data Taking and Special Runs

Data Taking Runs
Should run for parallel and perpendicular polarization for each kinematics, with open collimator, raster on, beam current 15 $\mu A$. For parallel kinematics, (target is in longitudinal polarization), polarization of the beam and the target needs to be reversed half way.

To reverse the polarization of the beam and the target, the following procedure needs to be followed:

For perpendicular kinematics, because there is no half waveplate for tranverse lasers, target polarization cannot be reversed. For the current quater waveplates setting, holding field should always be 270$\circ$. Never rotate field to 90$^\circ$. Optics runs
For each kinematics, take 15 minutes of $^{12}$C data with open collimators, no raster.

Acceptance runs
At kinematics x=0.33, do a momentum scan at (1$\pm$0.02)P$_0$=1.2936 and 1.3464 (GeV/c) with open collimator. $^{12}$C target, raster on, beam current 25$\mu A$. Run 1.6 hours (2.7 hours), and total number of events (both e$^-$ and $\pi^-$ no less than 0.7M for each point;

Reference Cell Runs
For each kinematics, do one run using N$_2$, and one run using $^3$He, with open collimators and raster on;

Momentum and angle changes
30 minutes for each momentum and angle change;

Target polarization measurement
Should do one NMR and one EPR measurement every 4 hours during the run, each will take about 20 minutes.
(Optional) Do continuous EPR monitoring every 4 hours, between two EPR/NMR measurements. Typically one continuous EPR monitoring takes 0.5 minutes, must be done with field feedback system on. More NMR, EPR measurements and other target tests need to be done during maintenance.

Target polarization change
Typically it takes 10 minutes to rotate the target polarization from perpendicular to parallel direction (and vice versa).

Other Special Runs
Moller: 1 hour, should be done
every 5 days;
after every spot change;
after every down time (maintenance or holiday);

Compton: continuous running during the experiment;

Beam energy measurement: 1 hour (ep) + 1 hour (ARC), should be done
at the beginning of data taking (6 GeV);
after every down time (maintenance or holiday);

BPM calibration: $\sim$ 5 minutes
Should check BeO target position and do BPM/harp once everyday.

OTR Measurement: 30 minutes Should be done once a day.

Before commissioning, do one survey at $20^\circ$;
On 06/19/01, do one survey at $45^\circ$ during 4 hours' weekly maintainance, then change spectrometer momentum (polarity) and spectrometer angle to $35^\circ$;
On 07/13/01, do one survey at $35^\circ$;
Then change spectrometer angle to $45^\circ$, do another survey;
On 07/19/01 (end of run), do one survey at $45^\circ$.

next up previous contents
Next: Run Plan Up: E99117_runplan Previous: Commissioning   Contents
Xiaochao Zheng 2001-06-09