[Sane-analysis] Half Wave Plate, runs 72945-7

[James Maxwell]

Hello all,

In the parallel runs at the end of the experiment, I've found 3 runs
that appear to have an incorrect value for the half wave plate status
in the ntuple.  Runs 72945 through 72947 have asymmetries of the
opposite sign, and we've been unable to track the sign change to the
beam or target polarizations.  See the following plot of asymmetries:

https://hallcweb.jlab.org/experiments/sane/wiki/index.php/Raw_Asymmetries#Fixing_Sign_from_Half_Wave_Plate:_8.2F19.2F2010
http://www.jlab.org/~jmaxwell/asym/polar_asym_script_no_cuts.txt

Looking through the Hall C log, we noticed there was trouble at MCC
with certain IOCs at the time when these runs occurred.  A guess may
be that during reboot, the hwp sign was set to a default 1, and once
everything was sorted out, it was corrected to -1.  Hamlet's shift
summary for this period is here:

https://hallcweb.jlab.org/hclog/0903_archive/090308155919.html

Please suggest any other explanation you may have for this sign
switch, and otherwise, take care with these runs.
Thanks,
James Maxwell