[G12] Meeting in 20 minutes!

[William Phelps]

Hello Everyone,
This is a reminder that there is a g12 Meeting in room B101 today at 11:00 am EST. 
http://clasweb.jlab.org/rungroups/g12/wiki/index.php/Nov2012
-Will


Current Meeting:
November 6, 2012
     -Update: Craig's wedding plans.
     -Fiducial cut prelims: Craig
     -(Johann) The following describes my method for determining the detection (AKA reconstruction) efficiency of g12 data for p, pi+ and pi-.
     -g p --> A B [C]
     -where A, B, C is some permutation of p, pi+, pi-
     -Shown below is the ratio of events where the missing particle [C] was successfully reconstruction.
          -For example: for the proton efficiency:
               -I took  g p --> pi+ pi- X   events
               -where the mass of X was around the proton's mass.
               -These events were the "denominator" of the ratio shown
               -Then, I took   g p --> pi+ pi- p   exclusive events
               -These events were the "numerator" of the ratio shown
     -8% of g12 total statistics was used. cuts on missing momentum and mass were similar to Craig's (above) but not exactly the same:
     -when all three particles are detected:
missing transverse momentum < 50 MeV
missing longitudinal momentum < 100 MeV  (AND'd with miss. transv. mom.)
|total missing mass squared| < 0.002 GeV^2
     -when only two particles are detected:
missing transverse momentum of (A + B) > 50 MeV
missing longitudinal momentum of (A + B) > 100 MeV  (OR'd with miss. transv. mom.)
missing mass of (A + B) ~= mass of C
Actual cuts are as follows:
|MM^2(pi+ + pi-) - M^2(p)| < 0.15 GeV^2
|MM^2(p + pi+) - M^2(pi-)| < 0.01 GeV^2
|MM^2(p + pi-) - M^2(pi+)| < 0.01 GeV^2
     -The data is plotted in bins of the momentum of [C]
proton efficiency.
pi+ efficiency.
pi- efficiency.
     -Some thoughts and conclusions, by Johann:
          -efficiency seems to be dependent on momentum
          -effect on total dataset is roughly as follows. Note that the positively charged particles do cover a larger kinematic range.
               -75% average efficiency for proton
               -88% average efficiency for pi+
               -95% average efficiency for pi-
          -With the exception of a few holes in the DC, the efficiency is relatively flat in the fiducial region so this correction may not need to be mapped out in theta/phi -- momentum only may suffice -- or perhaps in momentum and theta (just as in fiducial cuts)
     -Here are the same data presented in cos(theta) vs. momentum. The profile of each 2D histogram is included to show the average efficiencies of each particle:
proton efficiency.
proton efficiency profile.
pi+ efficiency.
pi+ efficiency profile.
pi- efficiency.
pi- efficiency profile.



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