Progress Report on GEANT Study of

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R. Ray 4/26/03
Progress Report on GEANT Study of Containerized
Detectors

• Implement containerized detectors in GEANT.
  Consider
• 1/3 XL and 2/3 XL sampling configurations.
• Use MINOS event generator, off-axis neutrino
  spectrum
• Weight interaction vertex in GEANT by number of
  target
• nucleons in various materials
• Parabolic fit to multiple tracks in an event.
  Assume
• longest track is electron.

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GEANT Implementation
Corner Blocks 10 x 10 x 10 cm3
2 mm thick steel skin
6.06 x 2.49 x 2.44 m3 shipping container
Detector dimensions 5.94 x 2.39 m2
2.8 cm thick Wood Floor (not shown)
5 cm x 5 cm box beams 1 cm wall thickness
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Consider two configurations 1/3 radiation
length sampling 2/3 radiation length sampling.
Detector x, y readout at each station. 3 cm cells
Absorber Polyethylene air 1/3 XL, r0.70, 10
detector stations.
Absorber Polyethylene air 0.625 XL, r0.73, 6
detector stations.
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50 kton Detector 4 x 10 x 50 Stack of Containers
15 cm horizontal and 20 cm vertical gaps
between detectors in adjacent containers
Cell Guides
50 kt of absorber 2.1 kt of steel 0.7 kt of
wood 0.14 kt of Al.
y
z
x
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Weighted Neutrino Energy Spectra
ne CC
Flat neutrino spectrum generated between 0.5 -
3.5 GeV for ne and 0.5 - 20 GeV for nm. Weight
applied at analysis level.
nm NC
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Event Reconstruction

• Essentially same as described yesterday by
  Leslie
• Hough Transform - step through slope and
  intercept space
• Find best straight line fit. Iterate.
• Assign hits within ? 15 cm of fit to track.
• Final parabolic fit to track.
• Eliminate all but the first few hits on track
  from further
• consideration
• Repeat to look for additional tracks.

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ne charged current
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ne charged current
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ne charged current
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ne charged current
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nm Neutral Current
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nm Neutral Current
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nm Neutral Current
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nm Neutral Current that Passes Cuts
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CUTS

• ? 1 reconstructed track in each view
• c2 of longest track in each view lt 50
• 10 (6) or more hit planes in each view
• Width of longest track (RMS) in each view lt 5.5
  cm2
• gt 1.4 hits/plane ave for longest track, combined
  views
• Fraction of hits on longest track/total hits gt
  0.80, combined views
• ( a fractional energy cut)
• 35 - 105 (24 - 60) hits on longest track,
  combined views
• (Red indicates different cut for 2/3 radiation
  length sampling)

Calculate Figure of Merit signal events/sqrt(ne
beam nm NC) normalized to LOI flux for 50
kton detector
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1/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
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1/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
cm2
cm2
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1/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
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1/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
GeV
GeV
GeV
GeV
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2/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
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2/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
cm2
cm2
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2/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
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2/3 Radiation Length Sampling
ne CC
nm NC
Cut distributions are weighted, successive
GeV
GeV
GeV
GeV
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1/3 Radiation Length Sampling
ne CC nm NC ne Center nm Center ne Beam nm Beam
Total Events (weighted) (467.8) 89.7 487.4 90.6 487.3 82.7
c2 lt 50 408.9 30.2 444.0 31.9 364.8 26.4
Nplanex,y ? 10 270.7 11.0 321.0 12.1 170.5 8.4
Track width gt 5.5 211.0 5.3 252.4 5.5 121.3 3.8
Ave hits/plane ? 1.4 185.6 0.8 221.4 1.0 98.9 0.6
Frac of hits on track gt 0.80 156.8 0.2 184.0 0.12 82.9 0.13
Hits on track bet 35-105 152.5 0.2 180.0 0.08 78.0 0.1
Efficiency 0.326 0.002 0.369 0.0009 0.160 0.001
Number of Events (LOI, 50 kt) 238.6 28.5 270.3 12.6
FOM 32.6 44.1
Events initiated in absorber Assumes 25
events from ne in beam
25
X
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2/3 Radiation Length Sampling
ne CC nm NC ne Center nm Center ne Beam nm Beam
Total Events (weighted) 472.8 82.4 487.4 79.0 486.7 73.4
c2 lt 50 349.2 17.9 384.4 21.2 250.6 15.1
Nplanex,y ? 10 262.3 11.4 303.5 12.5 145.0 8.8
Track width gt 5.5 206.1 5.6 228.2 5.7 107.3 3.9
Ave hits/plane ? 1.4 171.4 1.6 197.0 1.6 86.3 1.3
Frac of hits on track gt 0.80 142.8 0.58 165.2 0.4 72.5 0.49
Hits on track bet 24-105 121.6 0.31 146.1 0.12 56.4 0.10
Efficiency 0.257 0.004 0.300 0.001 0.116 0.001
Number of Events (LOI, 50 kt) 188.3 53.6 219.4 20.7
FOM 21.3 32.5
Events initiated in absorber Assumes 25
events from ne in beam
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Summary

• Electron efficiency and background rejection
  attainable with containerized
• detector appear reasonable, but you do pay
  a price in electron efficiency.
• Background from structural elements negligible.
• Difference between 1/3 XL and 2/3 XL sampling
  larger than in other analysis.
• Requires more investigation.
• Still to do
• Simulate beam ne and nm CC
• Add cross-talk (need a model) and RPC
  inefficiency
• Final optimization of cuts
• Generate new, high-statistics MC samples to
  smooth out peaks from large
• weight events and obtain final results
  independent of training samples.