Settings for fpp_scat_4
Remove carbon doors to do alignment of FPP chambers with straight through tracks. Use d(e,ep) quasi-elastic scattering at kinematics for elastic ep at Q2 = 1.1 GeV2 with hadron Q3 defocussed. Estimated time for measurement is 1/2 hour.
Beam Energy
4.045 GeV
Beam position
< .25 for x and y for 3A and 3B
Raster size
1.5x1.5mm
Beam Current
» 7-14mA. Set current to give maximum data rate with deadtime < 60%.
Target
15cm Deuterium
Spectrometer settings
Spectrometer  Momentum  Angle  Collimator 
Electron  3.459 GeV  16.12°  6msr 
Proton  1.202 GeV  53.06°  6msr
 
Magnet settings
Spectrometer  Dipole  Q1  Q2  Q3 
Electron  1.36131 T  2587.94 A  1481.20 A  1369.49 A 
Proton  0.4434 T  898.511 A  514.260 A  285.0 A
 

The electron quads are all set to negative polarity. The hadron Q1 set to positive polarity, but Q2 is set to negative polarity. Set hadron Q3 to negative polarity for defocussing ( The value in the table is also decreased by 60For a first guess at current for electron dipole either scale from earlier run or use 909 A/T. Suggest that the electron dipole be set to 10-3 level and then quads scaled to match.

Data taking
The T5 prescale should be one. The prescales for T1,T2,T3 and T4 should be set to give less than 5 Hz trigger rate for each. The T8 prescale should be set to maximum.

The trigger setup should be proton_1170-1700.settings .

The goal is 10,000 events which scatter between 5 - 20° in the carbon analyzer for each carbon thickness. Estimate that it will take 10 minutes per carbon thickness.