In addition to the proton inclusive data for the GE/GM measurement, we will take several test measurements. Runs will be taken at different beam currents in order to verify our measurement of the dead time in the spectrometers. Data will be taken with a thin carbon target at all kinematics as a check on the spectrometer pointing. Finally, because we define the kinematics by the proton angle, we can use the measured proton momentum as a check on the kinematics. While for a single setting, it is not possible to disentangle a momentum offset from a scattering angle offset, the magnets settings stay the same when the scattering angle is changed, and so any momentum offset will be identical at all epsilon points for a given Q2. The reproducibility of the magnet settings, important if one of the magnet trips and has to be reset, is 10-4, small enough that it is not a significant problem for kinematics checks. This will allow us to use the reconstructed momentum as an additional check on the kinematics.
Finally, coincidence data will be taken at some energies as a check of the scattering kinematics, and as a measure of proton detection efficiency and absorption (though these corrections almost completely cancel in the extracted ratios). For Q2=1.45 GeV2, we will take singles and coincidence data at coincidence kinematics at 1, 2, and 3 passes. Comparing the elastic cross section as measured by the protons and the electrons at one kinematics allows us to measure the proton inefficiency (due mainly to absorption). By comparing electron singles to proton singles at multiple kinematics (with a fixed proton momentum), we can also check the radiative corrections, which are significantly different for electron and proton singles.
Checkout, calibration, and sieve runs at 1.16 GeV. |
20 hours | |
Singles and coincidence H2 data at 3 beam currents. |
3+1 hours | 24 hours |
Move spectrometers to coincidence Q2 = 1.45 and survey. |
6 hours | |
Coincidence run at Q2 = 1.45. |
2+1 hours | |
Move electron spectrometer to proton Q2 = 0.5 and survey. |
6 hours | |
Data run at Q2 = 0.5 and 1.45. |
1+1 hours | |
Change energy to 2.26 GeV and move spectrometers. |
8 hours | |
Data run at Q2 = 0.5 and 1.45. |
2+1 hours | |
Survey spectrometers. |
6 hours | |
Move spectrometers to coincidence Q2 = 1.45 and survey. |
6 hours | |
Coincidence run at Q2 = 1.45 |
4+2 hours | |
Change energy to 5.56 GeV and move spectrometers. |
8 hours | |
Data run at Q2 = 0.5 and 1.45. |
1+1 hours | |
Survey spectrometers. |
6 hours | 62 hours |
Move spectrometers to Q2 = 0.5 and 3.20 and survey. |
6 hours | |
Data run at Q2 = 0.5 and 3.20. |
10+3 hours | |
Change energy to 2.26 GeV and move spectrometers. |
8 hours | |
Data run at Q2 = 0.5 and 3.20. |
8+2 hours | |
Survey spectrometers. |
6 hours | |
Change energy to 3.36 GeV and move spectrometers. |
8 hours | |
Data run at Q2 = 0.5 and 3.20. |
12+3 hours | |
Survey spectrometers. |
6 hours | |
Move spectrometers to coincidence Q2 = 1.45 and survey. |
6 hours | |
Coincidence run at Q2 = 1.45. |
4+2 hours | 84 hours |
Move spectrometers to Q2 = 0.5 and 4.90 and survey. |
6 hours | |
Data run at Q2 = 0.5 and 4.90. |
20+5 hours | |
Change energy to 5.56 GeV and move spectrometers. |
8 hours | |
Data run at Q2 = 0.5 and 4.90. |
20+5 hours | |
Survey spectrometers. | 6 hours | 70 hours |
Total | 240 hours |