[Gdh_lowq2] EG4 minutes (friday Feb 19)

[K Slifer]

Hyekoo
-Looking at the apparent Q2 dependence of PbPt.  He finds a reduced chis of
1.9 when fitting PbPt to a constant term.  To investigate, he compared the
DF for Q2 bins 23 and 24 (0.5 and 0.6 GeV2) for 30 runs.  Marco suggests to
increase the systematic uncertainty until the chi-squared is unity.  Hyekoo
will now evaluate PbPt for the entire 3 GeV data set and compare to the NMR
results.

Kangkang
-Looking at phi vs. theta, she sees a much different distribution than what
is shown on the reference page.  She will look directly at ntuple 10 next.
 She compared nphe before and after cuts and finds reasonable results.  Will
double check with Sarah's values.  Kangkang has incorporated the raster and
momentum corrections of Krishna into her code.  Will plot z vertex before
and after to verify.  She will have to obtain Krishna's latest raster
correction.

Krishna
-Investigated the large loss of events he was getting after applying cuts.
 He believes he fixed the issue (small coding errors and translation from
fortran to C++).  He now sees much less event loss. Hyekoo and Krishna will
choose one run and compare the number of events before and after all cuts
are applied.  Krishna has a new version of the raster correction, which
fixes some issues with the lowest beam energy.  Now has 21 parameters, with
6 params common to all energies.  No big difference for z vertex, but
noticeable improvement is seen for xy distribution.  The new correction also
helps a little in aligning pi+ and pi- distributions.  The fact that it does
not completely fix this problem probably indicates that the problem is not
solely due to a tilted magnetic field.

Marco
-Will include the new reference plots on the reference page.  Discusses
meaning of the gpart flag.
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