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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

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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

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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

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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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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

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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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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

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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

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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

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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