Here are the latest extractions of Ge/Gm using the nominal spin angle
of 48.84+/-0.5, and Q^2 variations of the average spin angle. I
include results for both |z| < 20 cm and |z| < 15 cm, both using |
phi| < 12 deg. There isn't much change between the two.
Also, I include a table of systematic errors, and bin-by-bin
extractions of 'hPz' and 'th_s':
For errors in Q^2, I use the most recent Q^2_e vs Q^2_p plot. It
looks a lot better at high Q^2, especially in the right sector after
the WC geometry fix, but there are still systematic differences--the
slope is even different in each sector (not physics), and it doesn't
get better at low Q^2 as before (probably coincidental). I think we
should quote at least 0.002 GeV^2 error in Q^2; that is the maximum
difference between Q^2_e and Q^2_p and just hope they aren't both
wrong! One other way we could test the error in Q^2 is to look at
the shape of the absolute cross section measured with BLAST. The
systematic errors by bin are listed below.
For errors in spin angle, the point-to-point errors are
negligible, as well as asymmetric errors in the left/right sector.
The derivatives d(gem)/d(beta) are shown below. The dominant error
is still due to an overall shift in the spin angle, approximately .
007/deg as quoted in my thesis.
I also extracted the spin angle bin-by-bin. But before quoting
those results, the error in the extraction due to Q^2 variation is
0.002 deg (l/r sym) and 3.6 deg (l/r asym). And the differences in
Q^2 the left and right sector have a definite asymmetric component.
Here is a table of the errors:
Q^2 gd(beta) dg(q+) dg(dq-) dg(db+) dg(db-) beta+/-err(deg) pol+/-
err(%)
0.166 -.00025 0.0058 -0.0147 0.0053 0.0291 45.756 1.422
51.27 1.28
0.196 .00000 0.0038 -0.0135 0.0053 0.0299 44.808 2.810
50.50 2.46
0.237 -.00055 0.0018 -0.0123 0.0064 0.0318 47.505 1.429
53.60 1.46
0.287 .00064 0.0002 -0.0111 0.0059 0.0319 49.822 2.416
56.95 2.78
0.350 .00025 -0.0010 -0.0099 0.0064 0.0344 42.184 3.302
50.07 2.58
0.423 -.00183 -0.0019 -0.0088 0.0081 0.0392 43.472 3.602
50.36 3.05
0.505 .00039 -0.0028 -0.0081 0.0049 0.0405 40.507 4.822
47.22 3.41
0.595 .00088 -0.0029 -0.0067 0.0037 0.0422 43.907 5.546
49.43 4.67
second column is the difference by putting in point to point spin
angle variations.
3,4th: q2 systematic errors in Ge/Gm
5,6th: beta systematic errors in Ge/Gm (ignore)
7-10th: bin-by-bin extraction of beta,pol
--Chris
TA-53/MPF-1/D111 P-23 MS H803
LANL, Los Alamos, NM 87545
505-665-9804(o) 665-4121(f) 662-0639(h)
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