Backgrounds, determination, systematic errors update

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Backgrounds, determination, systematic errors -
update

• Background subtraction, systematic errors,
  required precision
• Measuring the NC background
• Nue component of the beam

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Typical results L 735 km, R 10 km
Dm2 dependent !
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How well do we need to know the NC background?
Now

• If we know the expected background levels, then
  the experiment sensitivity is limit by
  statistical fluctuations of the background
  subtraction
• If the background in not known perfectly
  additional systematic error
• Only neutrinos, antineutrino statistical error
  dominates

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How well will we have to know the NC background
in the proton driver era?
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How will the systematic error affect the
measurement?
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Near detector? Sure, but where?
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Background composition at different near
detectors?
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Scaling from the near to far detectors
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Background as a fraction of the observed NC
candidates
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Nue component of the beam?

• Conjecture
• Nue component of the beam is primarily due to
  neutrinos from muon decays.
• Muon decays produce nues and numubars, hence a
  measurement of numubars (wrong sign muons) in
  the near detector will provide a constrant on the
  nue flux.
• Mark Messier This is wrong.

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Nue events, far detectors

• Histogram muon decays only

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Numubar events

• Histogram muon decays only

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Nue events, near site

• Histogram muon decays only

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Numubar events, near sites

• Histogram muon decays