all of the tensor data we have been taking for the past two weeks has now
been d(e,e'p) analyzed. results for the target tensor asymmetry
(A^{d}_{t}) and the beam-target tensor asymmetry (A^{d}_{et}) for
deuterium have been found.
the end result... the abs appears to produce around 10% tensor
polarization (at least according to this analysis).
roughly 100 runs were analyzed. quasi-elastic cuts were applied
(p_{missing} < 0.2 and m_{missing} = m_{neutron}). additionally, tancredi
found a nifty vertex cut that helped weed out some "bad" events; there was
also a slight cut in phi_{electron} imposed for more complicated reasons
than i care to write down.
the procedure for determining the tensor polarization was as follows:
1) fit the monte carlo tensor asymmetry to a cubic. in general, this fit
was very good.
2) fit the experimental tensor data to an equation linear in the monte
carlo cubic equation, i.e.:
(A^{d}_{T})_{EXP} = alpha * (monte carlo cubic) + beta
3) providing the offset (i.e. beta) is close to zero, it then follows that
P_T = alpha
the tensor runs go from run #1353 to 1686. somewhere around #1525 or so,
something mysterious happened to some aspect of blast which caused chi's
asymmetries to go away (see his e-mail from yeserday). as such, i have
produced three sets of polarization values: one for the runs between #1353
and #1524, one for the runs between #1525 and #1686, and one for all of
the runs. for each run set, i determined a value for P_T for events
with electrons in the left and the right sectors. the results are:
data set left P_T(%) left offset right P_T(%) right offset
------------- ----------- -------------- ------------ -------------
#1353 - #1524 5 +- 8 (6 +- 6)*10e-3 18 +- 8 (1 +- 1)*10e-2
#1525 - #1686 20 +- 9 (9 +- 6)*10e-3 4 +- 8 (1 +- 1)*10e-2
#1353 - #1686 11 +- 6 (1 +- 3)*10e-3 10 +- 5 (1 +- 7)*10e-3
false asymmet 4 +- 5 (3 +- 1)*10e-3 negative not applicable
anyway, considering that the left and right polarization determinations
were made in the same run, they should be equal. as such the #1353 -
#1686 data set is maybe the "best" of the three. thus 10% tensor
polarization.
i have included two plots. one is plots of the tensor asymmetries.
the other is a fit of the monte carlo cubic to the data.
enjoy...
aaron
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