Single Lepton Efficiency

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Single Lepton Efficiency
8 e/e- embedded in CC_at_2AGeV in separated
files. HGeant v705 Hydra 705 pid/pidutil/pair
updated modules (04/05) 8 MegaLepton calculated
so far ( for each species)-gtfactor 5 more is
ongoing.
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Single Lepton Efficiency

• We White electron/positron
• Single track cuts
• Rich, Shower, Chi2, beta.
• Pairs Cut
• opening angle (9 deg.)
• double hit cut
• CP candidate (track in which vicinity (9 deg
  region) another track was removed)
• RECURSIVE!! ( not only pairs are rejected but
  also all tracks belonging to rejected pairs) -gt
  this can affect the single track efficiency
• All We close pairs (O.A.lt9 deg.) are not used for
  the calculation of the efficiency

0ltplt2000MeV/c 0ltqlt90 0ltflt360
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Method
Calculated like We lepton sought in the pair
container, ONLY in pairs together with a
background (from CC) lepton. If it is found the
isCut variable is stored. If anything is found -gt
Loop in the HPidParticleSim container.
Note All pairs are stored in the HPairSim
container the cut information is stored in the
isCut data member
Matrices built dividing yield of recosntructed
leptons under different cut with the yield of the
leptons in the geometrical acceptance.
Smearing of the 2D Q versus F matrices that are
used to build the 3d matrices ( this must be
changed!)
Efficiency correction given a pair with an
e(q,f,p) and an e-(q,f,p) the corresponding
efficiency is read from the matrices and the
factor f 1/(eff1(e(q,f,p) ) eff2(e-(q,f,p) ))
is used as a weight to build the pair spectrum
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Electron Efficiency (Only Single Track Cuts)
0ltplt100MeV/c
200ltplt300MeV/c
Bining 60 bins in f 15 in Q
20 in Momentum
400ltplt500MeV/c
Shown 1 picture every two momentum bins
1900ltplt2000MeV/c
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Electron Efficiency (ALL Pairs Cuts)
0ltplt100MeV/c
Efficiency reduced from maximaly 80 to maximaly
70 because of RECURSIVE pair cuts.
This cut is done using the data member of the
HPairSim container isCut0 if the We was
building a pair with a background lepton. If
the We was found only in the HPidParticleSim
container, no cut is applied.
1900ltplt2000MeV/c
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Losses
0ltplt100MeV/c
This picture shows the fraction of all We leptons
that fall in the acceptance that are rejected
because of the recursive cut of Opening Angle and
Double Hit. This corresponds to isCut10 in the
HPairSim container.
1900ltplt2000MeV/c
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Correction of the experimental data
Single lepton correction applied to likesign and
unlikesign pairs after all the cuts (ALL CUTS
all single track cuts Opening angle 9 deg. no
double hit no CP candidates, whereas OA and DH
cuts are applied recursively -gt tracks
deleted!) Combinatorial backgorund built and
subtracted
Unlikesign SIGNAL, absolutely normalized to the
LVL1
Normalized signal
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Correction of simulated data
Limit the single lepton correction applied to
pairs does not work for very limited pair
statistics like in the case of the UrQMD signal!
Efficiency corrected UrQmd signal
Pluto simulation for leptons only, full analysis
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Ratio Corrected-Uncorrected
Ratio for Experimental Signal
Mass MeV/c2
Ratio for Pluto Simulated Signal
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Summary

• Single Lepton efficiency matrices built using the
  newest Pair code.
• Full statistic (40 megaleptons) is going to be
  ready in days
• Code for the correction ready and commited
• 3D smearing a la Romain has to be applied.
• Open question How far can we use the efficiency
  correction based on simulations if the
  simulations do not look like the experiment?
• Statement embedding tracks in real events wont
  help much, since the problem is not the CC
  background but the single lepton efficiency.

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Inhaltsfolie

• Single Lepton Efficiency