Robert Cooper L. Garrison, L. Rebenitsch, R. Tayloe, R.
Thornton
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INTRODUCTION
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MI-12 Neutron Background Run Neutrons ~18 m from target 40 days
on target (60 days total) In-line behind beam target (ground) 1 kg
EJ-301 detector motivated SciBath placement
Slide 4
MI-12 Neutron Background Run Neutrons ~18 m from target 40 days
on target (60 days total) In-line behind beam target (ground) 1 kg
EJ-301 detector motivated SciBath placement
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THE SCIBATH DETECTOR
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Design Concept Bath of liquid scintillator ~40 cm length cubic
volume 3D array, crossed wave- length shifting fiber readout
768-channel with 64-anode PMT system (x12) IU custom-built DAQ ($70
per channel with PMT)
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The SciBath Detector 80 L liquid scintillator (LS) 88% mineral
oil 11% pseudocumene 1% PPO 768 (3-16x16) array wavelength-shifting
fibers (x,y,z axes) 1.5 mm diameter 2.5 cm spacing UV blue
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The SciBath Detector Pulsed LED calibration
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The SciBath Detector N 2 and LS plumbing
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The SciBath Detector Electronics readout & PMTs
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The SciBath Detector Electronics readout & PMTs
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Sample Event
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Anticipated Sensitivity (n events)
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n / Particle Discrimination
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muons
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n / Particle Discrimination neutrons
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PRELIMINARY NEUTRON ENERGY SPECTRUM
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Beam Spill Time / PE Structure Bin 6 Bin 10 Bin 11 Bin 12Bin
13Bin 16 Bin 20
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Beam Spill Time / PE Structure Softening of PE spectrum in
time
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Preliminary Analysis Roadmap 1.Measure proton PE response
2.Convert proton PEs to energy scale 3.Unfold spectrum of neutrons
from protons 4.Divide detector efficiency 5.Normalize to X units (X
= time, POT, triggers, etc.) Future spectra will combine 3. and 4.
in MC
Slide 21
Preliminary Analysis Roadmap 1.Measure proton PE response
2.Convert proton PEs to energy scale 3.Unfold spectrum of neutrons
from protons 4.Divide detector efficiency 5.Normalize to X units (X
= time, POT, triggers, etc.) Future spectra will combine 3. and 4.
in MC
Slide 22
SciBath In-Beam PE Spectrum PEs
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Preliminary Analysis Roadmap 1.Measure proton PE response
2.Convert proton PEs to energy scale 3.Unfold spectrum of neutrons
from protons 4.Divide detector efficiency 5.Normalize to X units (X
= time, POT, triggers, etc.) Future spectra will combine 3. and 4.
in MC
Slide 24
Proton Response and Quenching Birks Law used to convert to
energy deposit Handles quenching for large dE / dx
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Proton Response and Quenching Birks Law used to convert to
energy deposit Handles quenching for large dE / dx
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Energy Deposit Spectrum Assume everything is a proton recoil
and apply quenching formula 300 MeV protons can range-out in
SciBath.
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Preliminary Analysis Roadmap 1.Measure proton PE response
2.Convert proton PEs to energy scale 3.Unfold spectrum of neutrons
from protons 4.Divide detector efficiency 5.Normalize to X units (X
= time, POT, triggers, etc.) Future spectra will combine 3. and 4.
in MC
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A Quick Unfolding Algorithm Assume isotropic CM scattering
Assume uniform energy deposit Assume monotonic with endpoint
Integrate uniform cake layers n p EpEp EnEn
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A Quick Unfolding Algorithm Assume isotropic CM scattering
Assume uniform energy deposit Assume monotonic with endpoint
Integrate uniform cake layers
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A Quick Unfolding Algorithm Assume isotropic CM scattering
Assume uniform energy deposit Assume monotonic with endpoint
Integrate uniform cake layers
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A Quick Unfolding Algorithm Assume isotropic CM scattering
Assume uniform energy deposit Assume monotonic with endpoint
Integrate uniform cake layers
Slide 32
Unfolded Neutron Spectrum
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Preliminary Analysis Roadmap 1.Measure proton PE response
2.Convert proton PEs to energy scale 3.Unfold spectrum of neutrons
from protons 4.Divide detector efficiency 5.Normalize to X units (X
= time, POT, triggers, etc.) Future spectra will combine 3. and 4.
in MC
Slide 34
Detection Efficiency (MC)
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Predicted Neutron Spectrum
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Preliminary Analysis Roadmap 1.Measure proton PE response
2.Convert proton PEs to energy scale 3.Unfold spectrum of neutrons
from protons 4.Divide detector efficiency 5.Normalize to X units (X
= time, POT, triggers, etc.) Future spectra will combine 3. and 4.
in MC
Slide 37
Neutron Spectrum per Beam Spill 3 neutrons per spill (1 neutron
> 40 MeV)
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NEXT STEPS
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Underway Implement MC unfolding Least squares fit or maximum
likelihood? POT analysis Explore effect of n- capture tagging,
fiducial cuts, and PID Directional analysis Double scatter analysis
More Aggressive n / discrimination Validate with cosmic ns