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The Future of Neutrino Physics in a Post-MiniBooNE Era

The Future of Neutrino Physics in a Post-MiniBooNE Era. H. Ray Los Alamos National Laboratory. Outline. Introduction to neutrino oscillations LSND : The motivation for MiniBooNE MiniBooNE Overview & Current Status The Spallation Neutron Source. Standard Model of Physics.

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The Future of Neutrino Physics in a Post-MiniBooNE Era

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  1. The Future of Neutrino Physics in a Post-MiniBooNE Era H. Ray Los Alamos National Laboratory

  2. Outline • Introduction to neutrino oscillations • LSND : The motivation for MiniBooNE • MiniBooNE Overview & Current Status • The Spallation Neutron Source H. Ray

  3. Standard Model of Physics H. Ray

  4. Standard Model of Physics Neutrino Oscillations Observed Assume Neutrinos Have Mass Neutrino Oscillations Observed Assume Neutrinos Have Mass Introduce  mass into SM via RH field (Sterile Neutrinos) which mix w/ LH fields (SM ) Introduce  mass into SM via RH field (Sterile Neutrinos) which mix w/ LH fields (SM ) Use Oscillations to find Sterile Neutrinos Use Oscillations to find Sterile Neutrinos H. Ray

  5. Neutrino Oscillations Weak state Mass state cos  sin  e 1 =  cos  2 -sin  |(0)> = -sin  |1> + cos |2> H. Ray

  6. Neutrino Oscillations Weak state Mass state cos  sin  e 1 =  cos  2 -sin  |(t)> = -sin  |1> + cos |2> e-iE1t e-iE2t H. Ray

  7. Posc =sin22 sin2 1.27 m2 L E Neutrino Oscillations Posc = |<e | (t)>|2 H. Ray

  8. Neutrino Oscillations Distance from point of creation of neutrino beam to detection point m2 is the mass squared difference between the two neutrino states Posc =sin22 sin2 1.27 m2L E  Is the mixing angle E is the energy of the neutrino beam H. Ray

  9. LSND • 800 MeV proton beam + H20 target, Copper beam stop • 167 ton tank, liquid scintillator, 25% PMT coverage • E =20-52.8 MeV • L =25-35 meters • e + p  e+ + n • n + p  d +  (2.2 MeV) H. Ray

  10. The LSND Result • Different from other oscillation signals • Higher m2 • Smaller mixing angle • Much smaller probability (very small signal) ~0.3% H. Ray

  11. The LSND Problem • Something must be wrong! • Flux calculation • Measurement in the detector • Both • Neither m2ab= ma2 - mb2 Posc =sin22 sin2 1.27 m2L E Reminiscent of the great Ray Davis Homestake missing solar neutrino problem! H. Ray

  12. Confirming LSND • Want the same L/E • Want higher statistics • Want different sources of systematic errors • Want different signal signature and backgrounds m2ab= ma2 - mb2 Posc =sin22 sin2 1.27 m2L E H. Ray

  13. MiniBooNE H. Ray

  14. MiniBooNE Neutrino Beam Fermilab • Start with an 8 GeV beam of protons from the booster H. Ray

  15. MiniBooNE Neutrino Beam World record for pulses pre-MB = 10M MB = 100M+ Fermilab • The proton beam enters the magnetic horn where it interacts with a Beryllium target • Focusing horn allows us to run in neutrino, anti-neutrino mode • Collected ~6x1020 POT, ~600,000  events • Running in anti- mode now, collected ~1x1020 POT H. Ray

  16. MiniBooNE Neutrino Beam Fermilab • p + Be = stream of mesons (, K) • Mesons decay into the neutrino beam seen by the detector • K+ / + + +  • + e+ +  + e H. Ray

  17. MiniBooNE Neutrino Beam Fermilab • An absorber is in place to stop muons and un-decayed mesons • Neutrino beam travels through 450 m of dirt absorber before arriving at the MiniBooNE detector H. Ray

  18. MiniBooNE Detector • 12.2 meter diameter sphere • Puremineral oil • 2 regions • Inner light-tight region, 1280 PMTs (10% coverage) • Optically isolated outer veto-region, 240 PMTs H. Ray

  19. Observing  Interactions • Don’t look directly for neutrinos • Look for products of neutrino interactions • Passage of charged particles through matter leaves a distinct mark • Cerenkov effect / light • Scintillation light H. Ray

  20. Cerenkov and Scintillation Light • Charged particles with a velocity greater than the speed of light * in the medium* produce an E-M shock wave • v > c/n • Similar to a sonic boom • Prompt light signature • Charged particles deposit energy in the medium • Isotropic, delayed H. Ray

  21. Event Signature H. Ray

  22. MiniBooNE • Lots of e in MiniBooNE beam vs ~no e in LSND beam • Complicated and degenerate light sources • Require excellent data to MC agreement in MiniBooNE MB :  e LSND :  e • Lots of e in MiniBooNE beam vs ~no e in LSND beam • Complicated and degenerate light sources • Require excellent data to MC agreement in MiniBooNE H. Ray

  23. Cerenkov light Scintillation light Fluorescence from Cerenkov light that is absorbed/re-emitted Reflection Tank walls, PMT faces, etc. Scattering off of mineral oil Raman, Rayleigh PMT Properties The Monte Carlo Sources of Light Tank Effects H. Ray

  24. Step 1 : External Measurements • Start with external desktop measurements IU Cyclotron 200 MeV proton beam Extinction rate = 1 / Extinction Length H. Ray

  25. Step 2 : Internal Samples • Identify internal samples which isolate various components of the OM • UVF, Scint are both isotropic, same wave-shifting/time constants • Low-E Neutral Current Elastic events below Cerenkov threshold H. Ray

  26. Step 3 : Verify MC Evolution • Examine cumulative 2/NDF distributions across many physics samples, many variables Background to CCQE Sample Calibration Sample Provide e Constraint Mean = 1.80, RMS = 1.47 Mean = 1.19, RMS = 0.76 Mean = 20.83, RMS = 25.59 Mean = 3.48, RMS = 3.17 Mean = 16.02, RMS = 25.90 Mean = 3.24, RMS = 2.94 H. Ray

  27. The Monte Carlo Chain External Measurements and Laser Calibration First Calibration with Michel Data Calibration of Scintillation Light with NC Events Final Calibration with Michel Data Validation with Cosmic Muons, CCQE, e NuMI, etc. H. Ray

  28. Quasi-Elastic  Events Constrain the intrinsic e flux - crucial to get right! H. Ray

  29. Signal Region e Events PRELIMINARY H. Ray

  30. MiniBooNE Current Status • MiniBooNE is performing a blind analysis (closed box) • Some of the info in all of the data • All of the info in some of the data • All of the info in all of the data Public Announcement April 11th H. Ray

  31. Final Outcomes Confirm LSND Inconclusive Reject LSND H. Ray

  32. Final Outcomes Confirm LSND Inconclusive Reject LSND Need to determine what causes oscillations H. Ray

  33. Final Outcomes Confirm LSND Inconclusive Reject LSND Need to collect more data / perform a new experiment H. Ray

  34. Final Outcomes Confirm LSND Inconclusive Reject LSND Need to determine what causes oscillations Need to collect more data / perform a new experiment SNS H. Ray

  35. Final Outcomes Confirm LSND Inconclusive Reject LSND H. Ray

  36. Final Outcomes Confirm LSND Inconclusive Reject LSND SNS H. Ray

  37. All Roads Lead to the SNS Confirm LSND Inconclusive Reject LSND Need to determine what causes oscillations Need to collect more data / perform a new experiment SNS H. Ray

  38. What is the SNS? Spallation Neutron Source Accelerator based neutron source in Oak Ridge, TN H. Ray

  39. The Spallation Neutron Source Hg • 1 GeV protons • Liquid Mercury target • First use of pure mercury as a proton beam target • 60 bunches/second • Pulses 695 ns wide • LAMPF = 600 swide, • FNAL = 1600 ns wide • Neutrons freed by the spallation process are collected and guided through beam lines to various experiments Neutrinos come for free! H. Ray

  40. The Spallation Neutron Source - absorbed by target E range up to 52.8 MeV Mono-Energetic! = 29.8 MeV +DAR Target Area (Liquid Mercury (Hg+) target) H. Ray

  41. The Spallation Neutron Source • +  + +  •  = 26 ns • + e+ +  + e •  = 2.2 s • Pulse timing, beam width, lifetime of particles = excellent separation of neutrino types Simple cut on beam timing = 72% pure  H. Ray

  42. The Spallation Neutron Source • +  + +  •  = 26 ns • + e+ +  + e •  = 2.2 s SNS • Mono-energetic  • E = 29.8 MeV • , e = known distributions • end-point E = 52.8 MeV MiniBooNE H. Ray GeV

  43. The Spallation Neutron Source Neutrino spectrum in range relevant to astrophysics / supernova predictions! H. Ray

  44. Proposed Experiments Osc-SNS Sterile Neutrinos -SNS Supernova Cross Sections H. Ray

  45. -SNS Near Detectors • Homogeneous, Segmented • Primary function = cross sections for astrophysics • Most relevant for supernova neutrino detection = 2H, C, O, Fe, Pb Full proposal submitted to DOE in August, 2005 H. Ray

  46. Osc-SNS Far Detector • MiniBooNE/LSND-type detector • Higher PMT coverage (25% vs 10%) • Mineral oil + scintillator (vs pure oil) • Faster electronics (200 MHz vs 10 MHz) • ~60m upstream of the beam dump/target • Removes DIF bgd H. Ray

  47. Neutrino Interactions Elastic Scattering Quasi-Elastic Scattering Single Pion Production Deep Inelastic Scattering SNS Allowed Interactions MeV GeV H. Ray

  48. Neutrino Interactions @ SNS • All neutrino types may engage in NC interactions Sterile Neutrino Search H. Ray

  49. Neutrino Interactions @ SNS • All neutrino types may engage in NC interactions • Muon mass = 105.7 MeV, Electron mass = 0.511 MeV • Muon neutrinos do not have a high enough energy at the SNS to engage in CC interactions! Sterile Neutrino Search Oscillation Search H. Ray

  50. Appearance Osc. Searches • 2 oscillation searches at SNS can be performed with CC interactions to look for flavor change • Appearance :   e (ala LSND) • e + p e+ + n • n + p  d + 2.2 MeV photon • Appearance :   e • e + 12C e- + 12Ngs • 12Ngs 12C + e+ (~8 MeV) + e • MiniBooNE uses e + n e- + p lower E e vs higher E e H. Ray

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