Results on e e- - production

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Results on ee- - production

• Aram Teymurazyan

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Single Arm analysis - Cuts

• Timing cut (-5s, 8 s)
• Position cut (ylt 5 cm)
• Limit the analysis to crystal part of HyCal using
  a restriction on lepton energy

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Single Arm analysis Timing Cut
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Single Arm analysis Timing Cut
The cut on for this plots was 15 ns, as a result
only 0.9 of events have an ambiguity in initial
photon (energy) selection
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ee- - production, Single Arm analysis
Sources of background pair production from beam
halo and Compton scattering
Only a timing cut is used for this plots
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Single Arm analysis ylt 5 cm cut
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Single Arm analysis ylt 5 cm cut
y lt 5cm cut effectively eliminates the
background from the beam halo, and practically
does not cut into the yield within the high
resolution crystal part of HyCal
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Single Arm analysis Compton Background

• Compton electrons affect only the electron arm
  of pair production events
• Compton photons are uniformly distributed

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Single Arm analysis Compton Background
By restricting the analysis to the Crystal part
of HyCal one effectively eliminates the Compton
photon background (Elepton gt 1.7 GeV). The y
lt 5 cm cut also helps to some extend.
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Single Arm analysis Compton Background
Compton electron background is simulated and
subtracted bin-by bin for the electron arm.
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Theoretical cross-section
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Theoretical cross-section
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Cross Section
Positrons
Electrons
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Cross Section
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ee- - production, summary of errors
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Cross Section
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Theoretical Cross-section
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Problems
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Problems