Beam Polarization: Raw Results 1998

Results 1998

• May 26, 1998. The beam polarization averaged over the runs 2424-2429 is 0.386+/-0.002(stat) (chi2=1.2/ndf). The full information is given here. The other runs were taken with different conditions and should not be included.
• May 28, 1998. The beam polarization averaged over the runs 2446-2450 is 0.396+/-0.0025(stat) (chi2=1.2/ndf). The full information is given here. The other runs were taken with different conditions and should not be included.
• May 30, 1998. The beam polarization averaged over the runs 2454-2464 is 0.394+/-0.002(stat) (chi2=1.6/ndf). The full information is given here. The other runs were taken with different conditions and should not be included.
• June 1, 1998. The beam polarization averaged over the runs 2496-2501 is 0.393+/-0.0022(stat) (chi2=0.3/ndf). The full information is given here. The other runs were taken with different conditions and should not be included.
• June 10, 1998. The beam polarization averaged over the runs 2608-2613 is 0.392+/-0.002(stat) (chi2=3.8/ndf). The full information is given here. The other runs were taken with different conditions and should not be included.
• June 12, 1998. The beam polarization averaged over the runs 2657-2993 is 0.395+/-0.0008(stat) (chi2=4.0/ndf). The full information is given here. The other runs were taken with different conditions and should not be included.
• June 15, 1998. The beam polarization averaged over the runs 2703-2711 is 0.392+/-0.0017(stat) (chi2=1.5/ndf). The full information is given here.
• June 19, 1998. LG channel number 7 is dead in the first 3 runs. The polarization in runs 2746-2747 is 0.383+/-0.004(stat) (chi2=1.0/ndf). The full information is given here.
• June 21, 1998. The polarization in runs 2767-2776 is 0.276+/-0.0017(stat) (chi2=2.7/ndf). The full information is given here. Hall C was running at 110 nA.
• June 22, 1998. The polarization in runs 2791-2798 is 0.310+/-0.001(stat) (chi2=2?/ndf). The full information is given here. Hall C was running at 50 nA.
• June 22, 1998. The polarization in runs 2812-2817 is 0.386+/-0.002(stat) (chi2=1.6/ndf). The full information is given here.
• June 23, 1998. Before spot moving. The polarization in runs 2826-2829 is 0.376+/-0.0022(stat) (chi2=3.0/ndf). The full information is given here.
• June 23, 1998. After spot moving. The polarization in runs 2844-2855 is 0.383+/-0.0013(stat) (chi2=2.0/ndf). The full information is given here.
• June 26, 1998. The target is cooled down to 114K. The polarization in runs 2880-2889 is 0.385+/-0.0015(stat) (chi2=4.0/ndf). The full information is given here.
• June 26, 1998. 3 halls are set to operate. Only Hall A gets a current. The polarization in runs 2893-2904 is 0.391+/-0.0015(stat) (chi2=2.5/ndf). The full information is given here.
• June 27, 1998. All 3 halls operate at 5 passes. Hall C was running at about 100nA. During the measurement it was turned on and off. The full run table is given here. One may also see an example of the ADC spectra.

  Measurements with Hall C running

  hall A current	0.59uA	1.4uA	1.5uA	3.55uA
  Hall C off	37.5+/-0.4%	not measured	37.5+/-0.2%	37.3+/-0.3%
  Hall C on	22.6+/-0.3%	32.7+/-0.2%	32.7+/-0.3%	35.7+/-0.3%

  Clear evidence for cross-talk effects between the two halls was found.

• June 30, 1998. The polarization in runs 2993-2996 is 0.381+/-0.002(stat) (chi2=1.5/ndf). The full information is given here.
• Aug 17, 1998. The beam energy is 1.833 GeV. The predicted spin angle at the target is 17^o. The transverse polarization should give a contribution of about 3% of the longitudinal one, with a target angle of 35^o. The polarization was measured with angles of 32^o (runs 3339-3352) and (180-35)^o (runs 3360-3363). The angles were estimated comparing the coincidence rates with a measurement at 90^o (perpendicular target, runs 3355,3357). Averaging the results with 32^o and (180-35)^o should cancel the transverse polarization impact. The polarization obtained is 0.497+/-0.25(stat)+/-1.2(target_angle). There is a bias (a false asymmetry?) between the results with opposite target polarization. No explanation found so far. It might be the beam intensity. The full information is given here.
• Aug 19, 1998, 18:45-20:30 The beam energy is 3.615 GeV. Runs 3360-3373 were taken at the injector angle of -38.^o. The polarization is about 0. The runs 3374-3387 were taken at the injector angle of 90.8^o, 3374-3377 at a target angle of (180-35)^o, 3378-3379 at a target angle of 90^o and 3380-3387 at a target angle of 33.3^o, the target angles measured using the rates. Starting with the run 3374 a new BCM circuit is installed which is sensitive to low currents. The polarization was measured averaging the results at the forward and at the backward target angles: 48.3+/-0.2(stat)+/-1.5(targ_angle)+/-1.5(other_system)% The full information is given here.
• Aug 20, 1998, 19:05-21:30 The beam energy is 3.615 GeV. The injector angle is 52.33^o Runs 3388-3393 were taken at a target angle of 33^o, runs 3394-3395 were taken at 90^o, runs 3396-3435 were taken at (180-33)^o, The runs 3404-3407 were taken at a low (injector) laser temperature, runs 3409-3412 at a higher temperature, the next runs while gradually reducing the cathode temperature. The results are presented on a plot. The asymmetry for the runs 3396-3435 was calculated normalizing by the BCM (not the pulser!). The average result at the default conditions (runs 3396-3399) is 61.1+/-0.3(stat)+/-1.0(targ_angle)+/-1.5(other_system)% The full information is given here.
• Aug 21, 1998, 14:00-14:40 The beam energy is 3.615 GeV. The injector angle is 52.33^o Runs 3436-3437 were taken at a low threshold. The results are presented on a plot. The average result at the default conditions (runs 3436-3449) is 60.8+/-0.15(stat)+/-2.0(syst)% The full information is given here.
• Aug 24, 1998, 24:00 The beam energy is 0.945 GeV. The injector angle is 100^o Runs 3450-3451 were taken at a low threshold. Runs 3452-3462 were taken at a target angle of 33^o, the runs 3463-3466 at (180-33)^o, the runs 3467-3469 at about 0^o. The results are presented on a plot for the positive and negative target angles. The average result (runs 3452-3466) is 56.0+/-0.5(stat)+/-3.0(syst)% The full information is given here.
• Sep 26, 1998, 24:00 The beam energy is 1.720 GeV. Mott results for Hall A laser is 71.9%.

  The injector angles were: 80^o, runs 3541-3546, 40^o, runs 3551-3572 and 20^o, runs 3578-3588. The runs 3541-3559 were taken with a 5um Fe target, the other runs were taken with 12.5um supermendur target. The Fe target polarization is calculated using the supermendur polarization of 0.076, for runs 3550-3562. The average results are: 44.6+/-0.2(stat)% at 80 degrees, 68.7+/-0.2(stat)% at 40 degrees, 40.6+/-0.2(stat)% at -20 degrees. The full information is given here, the last column presents the BCM asymmetry. This asymmetry happens to be about .003 - about 30 times larger than measured by HAPPEX.

• Sep 27, 1998, 24:00 The beam energy is 1.720 GeV. The injector angle is 63^o. The full information is given here, the last column presents the BCM asymmetry.
• Sep 28, 1998, 13:00-24:00 The beam energy is 1.720 GeV. The injector angle is 32^o - the optimal for Hall A. The full information is given here, the last column presents the BCM asymmetry. Dependence of the counting rates and polarization on the target angle was studied. The rate dependence matched the predicted angle (+/- 1 degree). A Coil+/- asymmetry persists. It may be caused at least partly by the beam helicity asymmetry.

  Later the same day: dependence of the results on the asymmetry of the coil currents +/- were studied. No considerable asymmetry was found.

  The resulting polarization is -69.5 +/- 0.2(stat) +/- 3.0(syst) (at H+ )

• 29 Sept 1998 13:10-18:00 The beam energy is 1.720 GeV. The injector angle is 50^o. The full information is given here, the last column presents the BCM asymmetry. The beam asymmetry was studied add ing a 1/2 wave plate. In the course of the measurement Matt Poelker made changes in the laser, trying to improve the polarization.

  Beam asymmetry for two helicities

  Laser change	1/2 wave out	1/2 wave in
  before	0.28+/-0.002%	0.014 +/- 0.003 %
  after	0.23+/-0.005%	-0.25 +/- 0.005 %

  An estimate of the beam polarization is -68.1 +/- 0.2(stat) +/- 3.(syst)%. The systematic error evaluation is very preliminary.

  Normalization the Fe polarization to the supermendur polarization of 7.6% using the runs 3753-3764 and 3744-3752 gives 6.9% for the Fe target.

  An error in the BCM linearity correction is found. Fixing it improves the +/- asymmetry: see the updated table. The results for all runs are plotted.

• 01 Oct 1998 13:10-23:00 The beam energy is 1.720 GeV. The injector angle is 50^o. Magnetic optics studies. During this measurement a high radiation damaged the lead glass detectors. The full information is given here.

  The resulting polarization is -68.0 +/- 2.0(stat) +/- 3.0(syst) (at H+ )

• 03 Oct 1998 21:20-22:40 The beam energy is 1.720 GeV. The injector angle is 50^o, the 1/2 wave plate was in. The full information is given here. The detector partially recovered. HV was increased by 50-100V, see the plots. The measurement were done with the supermendur target at different angles. The angles were calibrated using the rates.

  Target Angles

  Dial angle	Calculated angle	runs
  29	28.9	3866-3873
  151	148.3	3874-3877
  157	153.5	3878-3881
  157	153.	3882-3885
  26	24.8	3888-3891

  For the final measurement the runs:

  • 3882-3885: 66.0 +/- 0.4 chi2=2.8, the calculated target angle is taken.
  • 3888-3891: 69.5 +/- 0.4 chi2=0.6

  The resulting polarization is 68.0 +/- 0.3(stat) +/- 1.5(syst.target.rotation) +/- 2.0(syst)

• 05 Oct 1998 16:40-18:10 The beam energy is 1.720 GeV. The injector angle is 50^o, the 1/2 wave plate was in. The full information is given here. The detector recovered a bit more. Some HV were reduced by 10-20V. The measurement were done with the supermendur target at different angles. The angles were calibrated using the rates.

  Target Angles

  Dial angle	Calculated angle	runs
  25.5	24.1	3898-3903
  157	150.8	3906-3911
  150	144.5	3912-3917

  For the final measurement the runs:

  • 3898-3903: 70.0 +/- 0.3 chi2=4.3
  • 3906-3911: 63.7 +/- 0.3 chi2=0.6
  • 3912-3917: 62.8 +/- 0.3 chi2=0.8

  The resulting polarization is 66.9 +/- 0.2(stat) +/- 3.0(syst)

  If the calculated angles are used (see the table):

  • 3898-3903: 69.2 +/- 0.3 chi2=4.3
  • 3906-3911: 67.2 +/- 0.3 chi2=0.6
  • 3912-3917: 66.8 +/- 0.3 chi2=0.8

  The resulting polarization is 68.1 +/- 0.2(stat) +/- 3.0(syst)

• 11 Oct 1998 11:00-23:00 The beam energy is 1.720 GeV. The injector angle is 50^o, the 1/2 wave plate was out.

  Additional 1/2 wave plate was inserted in the circular polarized beam in order to minimize the linear component. Moller "pulser" readout was used in order to read the BCM (the x10 output was converted to frequency and counted in the Moller scalers). The full information is given here. A SIN curve was fit to the BCM asymmetries, shown on a plot, where the full circles show the first set of measurements while the open circles represent the second set of measurements. It seems that a phase shift happened between these two sets. In the first set of measurements the 1/2 wave plate was rotated from 0 to about 340 units (the units turned out to be different from degrees). Then it was turned back to 50 units and the result was consistent with the previous ones. Then, it was turned to 60 units and a jump happened, perhaps on the source side since nothing has been changed in the Hall A setup at this moment. It seems also that results are drifting all the time and it is not excluded that the phase would change to the opposite after some time. The "optimal" for this moment angle of 120 units was left on the device (see the open circles). The BCM asymmetry measured at this point was drifting between 0.12 and 0.18%.
  NB. The HAPPEX readout/analysis turned on for the last points of the second set provided values for the asymmetries very close to the ours, although with the opposite sign.

• 11 Oct 1998 23:40-00:20 The beam energy is 1.720 GeV. The injector angle is 50^o, the 1/2 wave plate was out. Mott: 72.0 (7 Oct 98). The target angle was measured:

  Target Angles

  Dial angle	Calculated angle	runs
  25.5	21.1	4037-4040
  88.5	-	4041-4042
  155	152.5	4043-4046

  The full information is given here and values recalculated for the angles calculated is given here.

  The final measurement with the initial angles:

  • 4037-4040: 70.8 +/- 0.6 chi2=1.5
  • 4043-4046: 65.2 +/- 0.7 chi2=2.3
  with an average of 68.0 +/- 0.4(stat)

  The final measurement with the calculated angles:

  • 4037-4040: 68.5 +/- 0.6 chi2=1.5
  • 4043-4046: 66.6 +/- 0.6 chi2=2.3

  with an average of 67.5 +/- 0.4(stat)

  The final result: 67.7 +/- 0.4(stat) +/- 3.0(syst-prelim)

• 14 Oct 1998 18:00-19:30 The beam energy is 1.720 GeV. The injector angle is 50^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in. Mott: 72.0 (7 Oct 98). The target angle was measured:

  Target Angles

  Dial angle	Calculated angle	runs
  25.5	20.2	4076-4089
  88.5	-	4090-4091
  155	153.7	4092-4099

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-13^o and the mean analysing power is 0.76 The error is statistical only.

  runs	Dial angle		Calculated angle		chi2	Re-calculated angle
  	angle	Polarization %	angle	Polarization %		angle	Polarization %
  4090-4091	88.5	-	-	-	-
  4076-4089	25.5	71.7+/-0.4	20.2	69.0+/-0.4	1.0	20.2	69.0+/-0.4
  4092-4099	155.0	65.3+/-0.5	153.7	66.0+/-0.5	0.3	154.6	65.5+/-0.5
  Average	-	68.5+/-0.3	-	67.7+/-0.3	-	-	67.5+/-0.3

  The full information is given here and values recalculated for the angles calculated is given here.

  The final measurement with the initial angles:

  • 4076-4089: 71.5 +/- 0.4 chi2=1.0
  • 4092-4099: 65.3 +/- 0.5 chi2=0.4
  with an average of 68.5 +/- 0.4(stat)

  The final measurement with the calculated angles:

  • 4076-4089: 69.1 +/- 0.5 chi2=1.0
  • 4092-4099: 66.0 +/- 0.4 chi2=0.4

  with an average of 67.7 +/- 0.4(stat)

  The final result: 68.1 +/- 0.4(stat) +/- 3.0(syst-prelim)

• 16 Oct 1998
  New energy: 4.234 GeV, linac=0.419 GeV, injector=0.047 GeV. The injector angle is 20. Mott: 71.0+/-0.6 (17 Oct 98).

  HV

  GeV	1	2	3	4	5	6	7	8
  1.720	1858	1791	1798	1793	1783	1798	1816	1840
  4.234	1750	1682	1698	1694	1674	1704	1711	1739

  The LG spectra are shown for the left trigger and the right trigger.
  It seems that the left aperture counter has low efficiency: it coincides with the left LG with a probability of about 25% (for the right arm this probability is about 80%).

  The wien filter angle is 50 degrees. We started measurements and the machine went down. The preliminary results are shown is given here.
  The average (runs 4130-4140) is 69.7 +/- 0.4(stat). Run 4141 is rejected because of poor statics and a vary bad quality of the beam.

• 18 Oct 1998 1:00-2:30 The beam energy is 3.402 GeV. The injector angle is 20^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in. Mott: 71.6+/-0.6 (21 Oct 98).

  The Aperture L HV was increased to 1850V in order to increase its efficiency. The LG spectra are shown for the left trigger. The target angle was measured:

  Target Angles

  Dial angle	Calculated angle	runs
  25.5	22.8	4149-4154
  88.5	-	4155-4156
  155	153.0	4157-4164

  The full information is given here and values recalculated for the angles calculated is given here.

  The final measurement with the initial angles:

  • 4149-4154: 74.0 +/- 0.3 chi2=1.2
  • 4157-4164: 69.7 +/- 0.3 chi2=0.6
  with an average of 71.8 +/- 0.2(stat)

  The final measurement with the calculated angles:

  • 4149-4154: 72.4 +/- 0.3 chi2=1.2
  • 4157-4164: 70.9 +/- 0.3 chi2=0.6

  with an average of 71.6 +/- 0.2(stat)

  The final result: 71.7 +/- 0.2(stat) +/- 3.0(syst-prelim)

• 23 Oct 1998 21:30-22:00 The beam energy is 3.400 GeV. The injector angle is 20^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in. Mott: 71.6+/-0.6 (21 Oct 98).

  The Aperture L HV was fixed - the light guide was glued back to the scintillator. The HV was moved back to 1750V. The target angle was measured:

  Target Angles

  Dial angle	Calculated angle	runs
  25.5	22.5	4212-4217
  88.5	-	4218-4219
  155	152.7	4220-4225

  The full information is given here.

  The final measurement with the initial angles:

  • 4212-4217: 74.2 +/- 0.3 chi2=0.6
  • 4220-4225: 69.4 +/- 0.3 chi2=1.0
  with an average of 71.8 +/- 0.2(stat)

  The final measurement with the calculated angles:

  • 4212-4217: 72.5 +/- 0.3 chi2=0.6
  • 4220-4225: 70.8 +/- 0.3 chi2=1.0

  with an average of 71.6 +/- 0.2(stat)

  The final result: 71.7 +/- 0.2(stat) +/- 3.0(syst-prelim)

• 27 Oct 1998 21:30-22:00 The beam energy is 3.400 GeV. The injector angle is 20^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in. Mott: 71.6+/-0.6 (21 Oct 98). The target angles and the polarization were measured:

  Target Angles and Beam Polarizations. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4234-4235	88.5	-	-	-	-
  4228-4233	25.5	74.1+/-0.3	22.9	72.6+/-0.3	0.8
  4236-4241	155.0	70.9+/-0.3	152.7	72.7+/-0.3	0.4
  Average	-	72.5+/-0.2	-	72.6+/-0.2	-

  The full information is given here.

  The final result: 72.6 +/- 0.2(stat) +/- 3.0(syst-prelim)

• 31 Oct 1998 11:10-12:50 The beam energy is 1.720 GeV. The injector angle is 35^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in. Mott: not done. The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The error is statistical only. The originally calculated angle uses only the 2-arm coincidence rates. At low energies this measurement is affected by multiple scattering in the target which reduces the coincidence rate at low angles (thicker targets). For re-calculation the single arms rate were used and their average was taken.

  runs	Dial angle		Calculated angle		chi2	Re-calculated angle
  	angle	Polarization %	angle	Polarization %		angle	Polarization %
  4254-4255	88.5	-	-	-	-
  4248-4253	25.5	74.4+/-0.3	23.5	73.2+/-0.3	0.8	22.4	72.6+/-0.3
  4257-4246	155.0	71.4+/-0.3	151.5	73.6+/-0.3	0.8	152.5	73.0+/-0.3
  Average	-	72.9+/-0.2	-	73.4+/-0.2	-	-	72.8+/-0.2

  Fe target, P=7.15% assumed for the moment. Target Angles and Beam Polarizations. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4272-4273	88.5	-	-	-	-
  4266-4271	25.5	71.2+/-0.5	22.8	69.7+/-0.5	2.0
  4274-4279	155.0	68.2+/-0.5	152.4	69.7+/-0.5	0.8
  Average	-	69.7+/-0.3	-	69.7+/-0.3	-

  The full information is given here.

  The final result: 72.9 +/- 0.2(stat) +/- 3.0(syst-prelim) (supermendur)

  The Fe target results indicate that its polarization is about 6.30+/-0.04

• 06 Nov 1998 20:00-20:45 The beam energy is 4.255 GeV. The injector angle is 34.9^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in. Mott: 73.3+/-0.6 (5 Nov 98). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4317-4318	88.5	-	-	-	-
  4309-4317	25.5	75.4+/-0.3	22.5	73.7+/-0.4	2.0
  4319-4324	155.0	71.0+/-0.3	152.7	72.4+/-0.4	1.6
  Average	-	73.2+/-0.2	-	73.0+/-0.2	-

  The full information is given here.

  The final result: -73.1 +/- 0.2(stat) +/- 3.0(syst-prelim) (at H+)
  

• 09 Nov 1998 08:50-09:30 The beam energy is 4.255 GeV. The injector angle is 34.9^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in (?). Mott: 73.3+/-0.6 (5 Nov 98). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4339-4340	88.5	-	-	-	-
  4333-4338	25.5	74.6+/-0.3	23.5	73.4+/-0.3	0.7
  4341-4346	155.0	70.6+/-0.3	151.2	73.0+/-0.3	3.0
  Average	-	72.6+/-0.2	-	73.2+/-0.2	-

  The full information is given here.

  The final result: -72.9 +/- 0.2(stat) +/- 3.0(syst-prelim) (at H+)
  

• 13 Nov 1998 08:50-09:30 The beam energy is 4.255 GeV (4.240 by EP). The injector angle is 34.9^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in (?). Mott: 73.3+/-0.6 (5 Nov 98).

  Counting rates from the apperture counters depending on the HV were measured (see the plot). The voltages used are:

  HV kV

  GeV	1	2	3	4	5	6	7	8	AL	AR
  4.240	1742	1683	1700	1695	1676	1706	1713	1750	1900	1800

  The spectra from LG are shown here.

  The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4368-4369	88.5	-	-	-	-
  4362-4368	25.5	73.5+/-0.3	23.8	72.5+/-0.3	1.0
  4370-4375	155.0	70.1+/-0.3	151.5	72.3+/-0.3	0.7
  Average	-	71.8+/-0.2	-	72.4+/-0.2	-

  The full information is given here.

  The final result: -72.1 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

  Levchuk effect studies

  Compared: L2 x (R1+R2+R3+R4) versus L2 x R2. The Levchuk effect is expected to increase the asymmetry for the latter while the former should be affected in the same way as the regular settings. It was assumed that the analysing power is 0.7778 (7/9).

  Levchuk effect studies.

  runs	Dial angle	type	Polarization %	chi2
  4370-4375	155.0	Regular	70.07+/-0.27	0.7
  4394-4401	155.0	Regular	70.43+/-0.22	1.5
  4377-4384	155.0	L2 x (R1+R2+R3+R4)	69.70+/-0.24	0.6
  4414-4418	155.0	L2 x (R1+R2+R3+R4)	70.11+/-0.23	1.2
  4385-4393	155.0	L2 x R2	70.49+/-0.33	1.5
  4402-4413	155.0	L2 x R2	70.74+/-0.24	2.3
  average	155.0	Regular	70.29+/-0.17	1.2
  average	155.0	L2 x (R1+R2+R3+R4)	69.91+/-0.17	0.9
  average	155.0	L2 x R2	70.66+/-0.19	1.8

  The difference between the cases 2 and 3 is (0.75+/-0.25)% absolute, or about (1.0+/-0.3)% relative.

  Conclusion: no significant effect is found at 1% level of precision.

• 23 Nov 1998 11:50-12:50 The beam energy is 0.862 GeV. The injector angle is -76^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in (?). Mott: 72.06 (23 Nov 98). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-5^o and the mean analysing power is 0.7736. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2	Re-calculated angle
  	angle	Polarization %	angle	Polarization %		angle	Polarization %
  4429-4430	88.5	-	-	-	-
  4423-4428	25.5	75.2+/-0.4	23.7	74.1+/-0.4	0.9	21.4	72.9+/-0.4
  4431-4436	155.0	71.1+/-0.4	149.9	74.5+/-0.4	1.0	151.7	73.2+/-0.4
  Average	-	73.2+/-0.3	-	74.3+/-0.3	-	-	73.1+/-0.3

  The full information is given here.

  The final result: 73.2 +/- 0.3(stat) +/- 3.0(syst-prelim)
  

• 02 Dec 1998 10:30-11:20 The beam energy is 2.591 GeV. The injector angle is -30.2^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in (?). Mott measurement gave 73.8+/-0.9% (see E-LOG entry 59494). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4451-4452	88.5	-	-	-	-
  4445-4450	25.5	71.1+/-0.3	23.5	70.0+/-0.3	0.5
  4453-4458	155.0	69.1+/-0.3	152.4	70.6+/-0.4	0.7
  Average	-	70.1+/-0.2	-	70.3+/-0.2	-

  The full information is given here.

  The final result: -70.2 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 04 Dec 1998 13:10-13:50 The beam energy is 2.591 GeV. The injector angle is -30.2^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in (?). Mott gave 74.1+/-?% (see E-LOG entry 59954). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4467-4468	88.5	-	-	-	-
  4461-4466	25.5	72.4+/-0.3	22.8	70.9+/-0.3	0.7
  4469-4476	155.0	69.3+/-0.3	152.6	70.7+/-0.4	2.1
  Average	-	70.8+/-0.2	-	70.8+/-0.2	-

  The full information is given here.

  The final result: -70.8 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 09 Dec 1998 12:40-13:30 The beam energy is 2.591 GeV. The injector angle is -30.5^o, the 1/2 wave plate was out, the additional 1/2 wave filter was in (?). Mott gave 74.1+/-?% (see E-LOG entry 59954). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4486-4487	88.5	-	-	-	-
  4480-4485	25.5	72.8+/-0.3	22.6	71.2+/-0.3	1.1
  4488-4493	155.0	68.2+/-0.3	151.3	70.5+/-0.3	0.3
  Average	-	70.5+/-0.2	-	70.8+/-0.2	-

  The full information is given here.

  The final result: -70.6 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 09 Dec 1998, evening 19:40-20:20 The beam energy is 2.591 GeV. The injector angle is -30.5^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?). Mott gave 74.1+/-?% (see E-LOG entry 59954). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4503-4504	88.5	-	-	-	-
  4497-4502	25.5	72.4+/-0.3	23.4	71.2+/-0.3	0.6
  4505-4510	155.0	69.3+/-0.3	152.0	71.1+/-0.3	1.1
  Average	-	70.9+/-0.2	-	71.1+/-0.2	-

  The full information is given here.

  The final result: 71.0 +/- 0.2(stat) +/- 3.0(syst-prelim)
  The sign is opposite to the previous measurements.

• 13 Dec 1998 16:50-17:30 The beam energy is 2.586 GeV. The injector angle is -30.5^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?). Mott gave 74.1+/-1.3% (see E-LOG entry 59954). The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4521-4522	88.5	-	-	-	-
  4515-4520	25.5	74.1+/-0.3	23.0	72.7+/-0.3	1.1
  4523-4528	155.0	69.9+/-0.3	150.9	72.5+/-0.3	0.6
  Average	-	72.0+/-0.2	-	72.6+/-0.2	-

  The full information is given here.

  The final result: 72.3 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 15 Dec 1998 23:20-00:20 The beam energy is 5.071 GeV. The injector angle is 40.^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?). No Mott measurement has been done.

  HV

  GeV	1	2	3	4	5	6	7	8
  5.071	1725	1663	1681	1666	1655	1683	1688	1733

  Quads

  Quad	1	2	3	Dipole
  kGs	0.900	0.500	2.183	8.981
  GL/BdL	8120	3610	15810	1475000

  The target angles and the polarization were measured:

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o? and the mean analysing power is 0.76 ?. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4559-4560	88.5	-	-	-	-
  4553-4558	25.5	74.0+/-0.3	22.8	72.5+/-0.3	1.6
  4561-4566	155.0	71.5+/-0.3	151.1	74.0+/-0.3	1.3
  Average	-	72.8+/-0.2	-	73.2+/-0.2	-

  The full information is given here.

  The final result: -73.0 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 19 Dec 1998 16:00-17:00 The beam energy is 5.071 GeV. The injector angle is 40.^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?). Mott: 72.4+/-0.5.

  A considerable beam charge asymmetry is found. This needs to be corrected by setting the "norbcm=1" parameter for asymp.kumac. The linearity factors found were: current=1821.+BCM*0.9606-.58E-7*BCM**2

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o? and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4577-4578	88.5	-	-	-	-
  4569-4576	25.5	71.7+/-0.3	23.9	70.8+/-0.3	0.5
  4579-4586	155.0	70.3+/-0.3	151.1	72.8+/-0.3	1.4
  Average	-	71.0+/-0.2	-	71.8+/-0.2	-

  Runs 4571-4574 and 4583-4586 were taken at higher threshold (200mV instead of 120mV).

  The full information is given here.

  The final result: -71.4 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 20 Dec 1998 22:20-23:20 The beam energy is 5.071 GeV. The injector angle is 40.^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?). Mott: 72.4+/-0.5.

  The beam charge asymmetry is low. Still, the "norbcm" correction is used, which shifts the final result for less that 0.2% (about 1 statistical error). parameter for asymp.kumac.

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o? and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4601-4601	88.5	-	-	-	-
  4596-4600	25.5	73.0+/-0.3	24.2	72.2+/-0.3	0.3
  4603-4609	155.0	73.3+/-0.3	152.9	74.6+/-0.3	0.7
  Average	-	73.1+/-0.2	-	73.4+/-0.2	-

  The full information is given here.

  The final result: -73.2 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 22 Dec 1998 17:40-18:40 The beam energy is 5.071 GeV. The injector angle is 40.^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?). Mott: 72.4+/-0.5.

  The beam is noisy. The "norbcm" correction is used.

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o? and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4618-4619	88.5	-	-	-	-
  4512-4617	25.5	71.6+/-0.3	23.6	70.5+/-0.3	0.8
  4620-4625	155.0	70.6+/-0.3	151.9	72.5+/-0.3	2.8
  Average	-	71.1+/-0.2	-	71.5+/-0.2	-
  4626-4629	155.0	69.1+/-0.4	thresh=200mV		0.6

  The full information is given here.

  The final result: -71.3 +/- 0.2(stat) +/- 3.0(syst-prelim)
  

• 24 Dec 1998 3:40-4:40AM The beam energy is 5.071 GeV. The injector angle is 40.^o, the 1/2 wave plate was IN, the additional 1/2 wave filter was in (?).

  Supermendur target P=7.6%. Target Angles and Beam Polarizations. The theta acceptance is about +/-14^o? and the mean analysing power is 0.76. The error is statistical only.

  runs	Dial angle		Calculated angle		chi2
  	angle	Polarization %	angle	Polarization %
  4638-4639	88.5	-	-	-	-
  4632-4637	25.5	72.7+/-0.3	23.5	71.6+/-0.3	0.85
  4641-4646	155.0	71.5+/-0.3	151.6	73.7+/-0.3	1.4
  Average	-	72.1+/-0.2	-	72.7+/-0.2	-

  The full information is given here.

  The final result: -72.4 +/- 0.2(stat) +/- 3.0(syst-prelim)