Geant4 NuMI Monte Carlo Uncertainties

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Geant4 NuMI Monte CarloUncertainties
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• The end goal of calculating the flux from Muon
  Monitor data relies upon ongoing work in the
  following areas
• GNuMI Monte Carlo reweighting for muons
  (provides muon distribution at End Cap)
• Muon Monitor calibration and data consistency
• G4NuMI Monte Carlo uncertainties in Muon Flux
• Fitting Muon Monitor data to Monte Carlo

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Uncertainties

• Density/Geometry
• 8 Aluminum Absorber Core blocks
• 10 Steel Absorber Core blocks
• BluBlocks
• Recesses for crane
• Concrete in shielding
• Recesses for crane
• Rock between Muon Alcoves
• Geometry
• Steel plates in gaps between Core and BluBlock
  shielding
• Excavated wall depth

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Aluminum Core blocks

• 8 blocks in Absorber Core
• Machined from 6061-T6 Heavy Duty Aluminum
• Density 2.70 /- 0.01 g/cm3
• Tolerances are /- .5 inch
• Cooling pipes
• Constitutes 2.2 of block volume for 32 pipes
• Avg. Aluminum block has 32/2 pipes, 1.1 volume
• Dealt w/ in separate analysis
• Uncertainty contribution (g/cm2)
• /- .01 g/cm3 (8 blocks 30.48 cm) 98.9
  2.41 g/cm2
• /- 1.27 cm 8 blocks 98.9 2.70 g/cm3
  27.13 g/cm2

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Steel Core blocks

• 10 blocks in Absorber Core
• Flame cut from Continuous Cast Salvage steel
• Density 7.842 /-.001 g/cm3 (9 random samples)
• Tolerances are /- .25 inch
• Cooling pipes same as Aluminum Block treatment
• Uncertainty contribution (g/cm2)
• /- .001 g/cm3 (10 blocks 23.11 cm) 97.8
  .226 g/cm2
• /- .635 cm 10 blocks 97.8 7.842 g/cm3
  48.70 g/cm2

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BluBlocks

• Form Cast by Duratek, INC
• Reclaimed steel from demolished building at Oak
  Ridge lab
• 88 Duratek BluBlocks
• Density 7.25 /-.35 g/cm3 (21 sheets QC)
• Tolerances are /- .50 inch
• Uncertainty contribution (g/cm2)
• /- .35 g/cm3 530cm 185.05 g/cm2
• /- 1.27 cm 4 blocks 7.25 g/cm3 36.83 g/cm2

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Concrete Blocks

• FNAL concrete blocks with rebar support
• Weight 10150 /- 50 lbs
• 7' x 3' x 3' with .5' and .25' tolerances
• 2 recesses for hoist hooks 15 x 7 x 5
• Density is 2.61 /- .02 g/cm3
• Uncertainty contribution (g/cm2)
• /- .02 g/cm3 91.5 cm 1.83 g/cm2
• /- .635 cm 1 block 2.61 g/cm3 1.66 g/cm2

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• Table of Uncertainties (g/cm2) for Data in Muon
  Monitor 1

• Most extra material the muon can travel through

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Rock

• Maquoketa Group - Brainerd Formation
• 6 (8) Samples from S-1271 over 10' range
• vertical range of Muon Monitors
• 2.79 /-.04 g/cm3
• 40' of rock between MM1 and MM2, and 60' of
  rock between MM2 and MM3
• Uncertainty contribution (g/cm2)
• /- .04 g/cm3 1219 cm 48.77 g/cm2 (MM1-2)
• /- .04 g/cm3 1829 cm 73.15 g/cm2 (MM2-3)
• Dimension uncertainty will come from survey
  analysis
• Placeholders are /- 1.5' for MM1-2 and /- 1'
  for MM2-3

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Shokrete

• Conrete sprayed onto walls
• 2.4 /- .2 g/cm3
• Bounded by Decay Tunnel backfill(2.22 g/cm3) and
  FNAL concrete blocks (2.61 g/cm3)
• 4 was the Shokrete target thickness w/ a 3
  uncertainty because of surface undulation
• Uncertainty contribution (g/cm2)
• /- .2 g/cm3 45.72 cm 9.14 g/cm2 (MM1-2)
• /- .2 g/cm3 30.48 cm 6.1 g/cm2 (MM2-3)
• /- 15.24 cm 2.4 g/cm3 36.58 g/cm2 (MM1-2 and
  2-3)

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• Table contributions to uncertainty in g/cm2

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Uncertainty to Flux

• The flux is the integrated muon distribution in
  each Muon Alcove 1, 2, 3. To get each
  distribution an efficiency plots of muons at the
  end of the Decay Pipe is multiplied by a
  provided(Zarko) distribution at the end of the
  Decay Pipe.
• The uncertainty in efficiency is directly related
  to energy loss which is in turn directly related
  to material between the end of the Decay Pipe and
  the Muon Alcoves

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Efficiency Plots

• Metric to examine the effect that changes to the
  G4NuMI MC have on muon flux is to look at an
  'Efficiency'
• E ( muon traversing muon monitor (1,2,3))/(
  muons produced)
• 30,000 muons
• mono-energetic muon beam uniformally distributed
  across Decay Pipe End Cap
• Samples at 1-120 GeV
• Uncertainty in g/cm2 is equivalent to density
  change

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Conclusions

• Look at uncertainty from survey points
• Combine uncertainties more constructively
• Convert g/cm2 uncertainty to Efficiency
  uncertainty