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NEUTRINO MASSES AND OSCILLATIONS Triumphs and Challenges

NEUTRINO MASSES AND OSCILLATIONS Triumphs and Challenges. R. D. McKeown Caltech. Outline. Historical introduction Neutrino Oscillations Vacuum Oscillations Matter Oscillations. Neutrino Masses The Near Future Outlook. 1913. 1869. ???. Historical Perspective. New “Periodic Table”.

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NEUTRINO MASSES AND OSCILLATIONS Triumphs and Challenges

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  1. NEUTRINO MASSES AND OSCILLATIONSTriumphs and Challenges R. D. McKeown Caltech

  2. Outline • Historical introduction • Neutrino Oscillations Vacuum Oscillations Matter Oscillations • Neutrino Masses • The Near Future • Outlook

  3. 1913 1869 ??? Historical Perspective

  4. New “Periodic Table”

  5. Discovery of the Neutrino – 1956 F. Reines, Nobel Lecture, 1995

  6. EarlyHistory • 1936- discovery of the muon (I. Rabi: Who ordered that ??) • 1950’s - discovery of n’s at nuclear reactors • 1958 – B. Pontecorvo proposes neutrino oscillations • 60’s and 70’s – n were studied with accelerator experiments ne≠ nm "All you have to do is imagine something that does practically nothing. You can use your son-in-law as a prototype."

  7. More Recent History • 1968 – 1st solar n anomaly evidence • 1980’s – new interest in neutrino masses and oscillations: n’s as dark matter?? • 1980-present: the quest for neutrino oscillations • 1998 Super-Kamiokande obtains first evidence for neutrino oscillations

  8. Two Generation Model 1.24 (Peg minimum)

  9. 1.24 (Pegminimum) Length & Energy Scales Super-K!! En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km

  10. 30 kton H20 Cherenkov 11000 20” PMT’s

  11. Neutrino Oscillation Interpretation Super-Kamiokande Results Wn> 0.001 gK2K, MINOS

  12. 1.24 (Pegminimum) Length & Energy Scales Super-K En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km Chooz, Palo Verde En= 1 MeV, Dm2=10-3 eV2 , L = 1.2 km

  13. Reactor Neutrino Experiments • ne from n-rich fission products • detection via inverse beta decay (ne+pge++n) • Measure flux and energy spectrum • Variety of distances L= 10-1000 m

  14. Precise Measurements Flux and Energy Spectrum g ~1-2 %

  15. Early Reactor Oscillation Searches 103 Distance (m)

  16. Enter • Long Baseline (180 km) • Calibrated source(s) • Large detector (1 kton) • Deep underground (2700 mwe)

  17. 1.24 (Pegminimum) Length & Energy Scales Super-K En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km Chooz, Palo Verde En= 1 MeV, Dm2=10-3 eV2 , L = 1.2 km En= 1 MeV, Dm2=10-5 eV2 , L = 125 km

  18. Designed to test solar neutrino oscillation parameters on Earth (!) KamLAND has a much longer baseline than previous (reactor) experiments Statistical errors only

  19. Only a few places in the World could host an experiment like KamLAND…

  20. Kashiwazaki Takahama Ohi KamLAND uses the entire Japanese nuclear power industry as a long­baseline source

  21. Narrow baseline range: 85.3% of signal has 140 km < L < 344 km • The total electric power produced “as a • by-product” of the n’s is: • ~60 GW or... • ~4% of the world’s manmade power or… • ~20% of the world’s nuclear power

  22. Spectrum Distortion

  23. KamLAND Detector 1000 Ton (135 mm) 1879 (Cosmic veto)

  24. Selecting antineutrinos, Eprompt>2.6MeV 5.5 m fiducial cut • - Rprompt, delayed < 5.5 m • - ΔRe-n < 2 m • - 0.5 μs < ΔTe-n < 1 ms • 1.8 MeV < Edelayed < 2.6 MeV • 2.6 MeV < Eprompt < 8.5 MeV • Tagging efficiency 89.8% (543.7 ton) Balloon edge • …In addition: • 2s veto for showering/bad μ • 2s veto in a R = 3m tube along track • Dead-time 9.7%

  25. Solar n: Dm2 = 5.5x10-5 eV2 sin2 2Q = 0.833 G.Fogli et al., PR D66, 010001-406, (2002) Ratio of Measured and Expected ne Flux from Reactor Neutrino Experiments

  26. Measurement of Energy Spectrum

  27. Oscillation Effect

  28. KamLAND best fit : Dm2 = 7.9 x 10-5 eV2 tan2q = 0.45

  29. Solar Neutrino Energy Spectrum

  30. More missing neutrinos…

  31. Neutrino Oscillations? Rorbit “Just So ??? “

  32. 1.24 (Pegminimum) Length & Energy Scales Super-K En= 1 GeV, Dm2=10-3 eV2 , L = 1240 km Chooz, Palo Verde En= 1 MeV, Dm2=10-3 eV2 , L = 1.2 km En= 1 MeV, Dm2=10-5 eV2 , L = 125 km En= 1 MeV, Dm2=10-11 eV2 , L = 108 km

  33. n2 n1 Matter Enhanced Oscillation (MSW) Mikheyev, Smirnov, Wolfenstein

  34. Enter SNO… ne + d g p + p + e- ( CC ) nx + d g p + n + nx ( NC ) nx + e-gnx + e- ( ES )

  35. Neutrino Mixing • Neutrino Masses • Flavor Oscillations +

  36. Combined fit with solar neutrino data Dm2=7.9+0.6-0.5x10-5 eV2 tan2q=0.40+0.10-0.07

  37. Open circles: combined best fit Closed circles: experimental data

  38. RECENT NEWSMiniBOONE refutes LSND! LSND ruled out at 98% confidence

  39. Maki – Nakagawa – Sakata Matrix Future Reactor Experiment! CP violation

  40. < Why so different???

  41. New “Periodic Table”

  42. The Mass Puzzle M “Seesaw mechanism”

  43. Why haven’t we seen nR?Extra Dimension • All charged particles are on a 3-brane • Right-handed neutrinos SM gauge singlet  Can propagate in the “bulk” • Makes neutrino mass small (Arkani-Hamed, Dimopoulos, Dvali, March-Russell; Dienes, Dudas, Gherghetta) • Barbieri-Strumia: SN1987A constraint “Warped” extra dimension (Grossman, Neubert) or more than one extra dimensions • Or SUSY breaking (Arkani-Hamed, Hall, HM, Smith, Weiner; Arkani-Hamed, Kaplan, HM, Nomura) (From H.Murayama)

  44. The Quest for q13at the Daya Bay Nuclear Power Plant • Baseline ~2km • More powerful reactors • Multiple detectors → measure ratio

  45. Daya Bay nuclear power plant • 4 reactor cores, 11.6 GW • 2 more cores in 2011, 5.8 GW • Mountains provide overburden to shield cosmic-ray backgrounds

  46. DYB NPP region Location and surroundings 55 km

  47. Experiment Layout

  48. Detector modules • Three zone modular structure: I. target: Gd-loaded scintillator II. g-catcher: normal scintillator III. Buffer shielding: oil • Reflector at top and bottom • 192 8”PMT/module • Photocathode coverage: 5.6 %  12%(with reflector) 20 t Gd-LS LS oil Target: 20 t, 1.6m g-catcher: 20t, 45cm Buffer: 40t, 45cm

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