1. Used the kumac, asym_plot.kumac , to determine the corrected asymmetry for the elastic peak for each run. Before running the kumac , the tcl script, get_pol.tcl, must be run to create the files which list: run number, target type ( 10=bottom,20=top) , target polarization, beam polarization, charge asymmetry, run time for h+,run time for h-, charge for h+ and charge for h-. The tcl script creates files for the top and bottom target runs. The kumac loops through both target types for a given target field ( parallel or perp) for all the runs. A separate kumac, fit_12C_shape.kumac, was used to fit the shape of W between 0.7 and 1.2 GeV for C+He runs 43775 for parallel and  43229 for perp. The fit was a third order polynomial. The coefficients for the fit are put into the asym_plot.kumac.  In the asym_plot.kumac, first the dilution factor is determined. All histograms are cut on 0.8 < hsshtrk/hsp < 1.4 for PID. The background polynomial is fit by a scale factor  to the region  of W between 0.7 to 0.8 ( previously I had been fitting the region W between 0.8 to 0.88 GeV).  The region of W to determine the dilution factor and asymmetry was 0.9 to 1.0 and 0.85 to 1.05. The scaled polynomial is integrated between the limits to get the total number of background counts.  The number of elastic events is taken from the total sum in the region minus the background counts. To get the asymmetry, a histogram of W gated on  h+ ( helicity.ge.32768) and h- (helicity.lt.32768) are created for W between 0.85 and 1.05 GeV. The raw asymmetry, A_raw =  (h- - h+)/(h- + h+) and the error is 2*sqrt(h+*h-)/(h++ h-)/sqrt(h+ + h-).  The corrected asymmetry is (A_raw-Charge_asym)/(1-A_raw*Charge_asym)/(beam pol)/(target pol)/( dilution factor). The asymmetry is also calculated for smaller scattering angle bins. Also for the entire theta range but in different W bins. I did to bins of 0.025 GeV for W between 0.9 and 1.0 GeV , and did bins of 0.050 GeV for W between 0.85 and 1.05 GeV.

2.  Correction to the asymmetries.  After running the above kumac, I ran separate kumacs which change the sign of the asymmetry and applied a correction factor of 1/1.019 to the top target runs and 1/1.018 to the bottom target runs and to get the weighted average for the group of runs with the new factors. ( See mail archive message)

3.  Parallel target field: The beam energy was 5.7526 GeV after energy loss. The average scattering angle was 13.02 degrees and the azimuthal angle was 269 degrees ( 0 degrees is pointing down, 90 is pointing towards the SOS and 270 is pointing towards the HMS).  The Q2 = 1.47 , theta_q = 50.86 . With the target field pointing at 180 degrees then theta_star=129.14 degrees and phi_star = 180 degrees. A plot ( need to update) of the corrected asymmetry as a function of run number shows the bottom and top targets with different colors. The average asymmetry integrated over the W between 0.9 and 1.0 is for bottom is  0.176 +- 0.004 and for top is 0.194 +- 0.003 .  The two disagree by 0.018 (4-5 sigma) or about 9% .  The calculated asymmetry for this kinematics is 0.216  ( using muGep/Gmp = 0.83 from Hall A FPP data) but the asymmetry is very insensitive to the value of Gep/Gmp . A 40% change in Gep/Gmp changes the calculated asymmetry by about 2%.  The run number, elastic W peak , elastic W width, target polarization, beam polarization, dilution factor, average scattering angle, charge asym, raw asymmetry, error, corrected asymmetry, error, charge, time , average current are listed in a file for the top and bottom. ( need to update)

4. Perpendicular target field: The beam energy was 5.7526 GeV after energy loss. The average scattering angle was 13.25 degrees and the azimuthal angle was 257 degrees ( 0 degrees is pointing down, 90 is pointing towards the SOS and 270 is pointing towards the HMS).  The Q2 = 1.51 , theta_q = 50.37 . With the target field pointing at 90 degrees then theta_star= 39.63 degrees and phi_star = 167 degrees. A plot of the corrected asymmetry as a function of run number shows the bottom and top targets with different colors. The average asymmetry for integrated over the W between 0.9 and 1.0 for top is  -.0935 +- 0.004 and for bottom it is  -0.0946 +- 0.004 .  The two agree well. The asymmetry from all runs is -0.0940 + - 0.0028.  The calculated asymmetry for this kinematics is -0.111 ( using muGep/Gmp = 0.83 from Hall A FPP data) but the asymmetry is sensitive to the value of Gep/Gmp . A 2% change in Gep/Gmp changes the calculated asymmetry by about -2%.  The run number, elastic W peak , elastic W width, target polarization, beam polarization, dilution factor, average scattering angle, charge asym, raw asymmetry, error, corrected asymmetry, error, charge, time , average current are listed in a file for the top and bottom (need to update). I removed runs 43299-43305  since the HV for the scintillators was changed for these runs which changed the shape of the W spectrum and the background fit would overshoot at W > 1.0 leading to  too low a dilution factor.


5.  Asymmetry dependence on scattering angle: Plot of asymmetry versus electron scattering angle in four theta bins for perpendicular ( parallel ) target field ( need to update). Top and bottom cells are plotted separately.  In addition there are points for the asymmetry determined for 0.9 < W < 1.0 and 0.85 < W < 1.05 for both top and botton.  Also in the plots are points for just two theta bins with the top and bottom combined for the different W regions. The two W regions agree nicely. We seem to have enough statisitics to divided the data into two theta bins which correspond to Q2 of  1.37 and  1.65 GeV2.

In the plots the predicted asymmetry assuming Ge/Gm from polarization transfer [ muGe/Gm =1-0.14*(q2-0.3) ] and assuming muGe/Gm=1 are plotted as black and blue lines. For the parallel setting the two predictions are on top of each other. The slope in the parallel setting is due to the change in the kinematics ( Q2 changes from  1.1 to 2.0 as scattering angle changes from 11 to 16 degrees) .  the data match the slope and if one multiplies by 1.26 then the data will lie on the predicted line. For perpendicular setting, the two predictions are shifted indicated  the sensitivity to Ge/Gm. The main cause of the slope is changing kinematics. But  the slopes are different in the perpendicular case, since the prediction from polarization transfer has a Q2 dependence for Ge/Gm. The data points cluster around the line for muGe/Gm = 1, but if the data are multiplied by 1.26 then the data lie on the muGe/Gm measured in Hall A.

6. Dependence of Asymmetry on W.  There should be no dependence on W and this is a check. Plot of asymmetry versus W in to sets of 4 W bins for perpendicular ( parallel ) ( need to update) target field. One set is steps of W in 50 MeV from 0.85 to 1.05 GeV. The other set is steps in W of 25 MeV from 0.9 to 1.0 GeV. The dilution factor is about  0.03, 0.55, 0.38, 0.13 for bins of W = 0.85-0.90, 0.90-0.95, 0.95-1.0, 1.0-1.05. The dilution factor is about  0.43, 0.62, 0.44,0.28 for bins of W = 0.90-0.925, 0.925-0.95, 0.95-0.975 , 0.975-1.0 .

7. Different method to get asymmetry.  Determined the count asymmetry for all runs by determining the count asymmetry for each run and taking the weighted average of all runs using the kumac. Plots of count asymmetry versus W for perp and parallel with the average count asymmetry in the region of 0.7 < W < 0.85 of 0.0084 +- 0.003 for perp and 0.0033 +- 0.003 for parallel. Then sum all runs together and determine the dilution factor using the background shape of 12C+He runs fitted to the region of 0.7 < W< 0.85. PLots of the dilution factor versus W for perp and parallel. The dilution factors for the top and bottom cells are the similar. Then combined the dilution factor and the count asymmetry data to make plots of the corrected asymmetry versus W for perp and parallel. The weighted average for the region of 0.9 < W < 1.0 is -0.0883 +- 0.003 for perp and 0.177 +- 0.0025 for parallel .  These values are almost identical to what was determined by the previous method. The difference between the two methods is that previously the dilution factor was determined for each run and in this method one dilution factor is determined for all runs.

8. Use Monte Carlo to get dilution factors.  Ran the single arm Monte Carlo with NH3 target for parallel and perpendicular target fields at high momentum setting.  Compare using cut of abs(hsdelta) < 8%. Then fit the MC over the region 0.7 < W< 1.1 with a gaussian + p4 + p5*W + p6*W*W. Plots show the fit to the MC ( with a test on the MC ntuple to eliminate the H3 part of the target) for the perp and parallel target fields. Also in the plots are the C+He  data. One can see that the shapes of the MC are different than the C+He data .  The dilution factor can by determined by  scaling the MC polynomial in the region of 0.7 < W < 0.85 GeV for the NH3 data. Summing up all the runs for the top and bottom targets, The dilution factor is plotted for perp and parallel target field.

9.  Comparison to MC looking at elastic yield.  Ran the single arm Monte Carlo with NH3 target for parallel and perpendicular target fields at high momentum setting using packing fraction of 50%. Compare using cut of abs(hsdelta) < 8%. Fit the background ( select everything in target except proton) with a gaussian + p4 + p5*W + p6*W*W.  Plots show the fit to the MC for perp and parallel.       The back ground shape is normalized to the data in the region 0.7 < W < 0.85 . The normalized back is subtracted from the data to get the elastic proton data. Plots for perp and parallel.  The MC is normalized by a factor of 1.14 which was the factor needed to get agreement between the 12C ( noHe) data and MC.  Plots comparing NH3 for MC to data for perp and parallel.  For the perpendicular setting there is a clear need for a different packing fraction. For the parallel case the data and MC match fairly well. Plots comparing elastic proton scattering yield for MC and data for perp and parallel.  For perpendicular setting the ratio data/MC = 0.92 for the region 0.9 < W < 1.0 GeV and the radiative tail region clearly does not match. For parallel setting the ratio data/MC = 0.88 for the region 0.9 < W < 1.0 GeV.