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A Deep Ocean Anti-Neutrino Observatory

A Deep Ocean Anti-Neutrino Observatory

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A Deep Ocean Anti-Neutrino Observatory

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  1. A Deep Ocean Anti-Neutrino Observatory An Introduction to the Science Potential of Hanohano Presented by Steve Dye University of Hawaii at Manoa Hawaii Pacific University NOW 2006

  2. Outline • Neutrino Geophysics • U/Th mantle flux • Th/U ratio • Geo-reactor search • Neutrino Oscillation Physics • Mixing angles θ12 and θ13 • Mass squared difference Δm231 • Mass hierarchy NOW 2006

  3. Hawaii Anti-Neutrino Observatory† Location flexibility • Far from continental crust and reactors for neutrino geophysics- Hawaii • Offshore of reactor for neutrino oscillation physics- California, Taiwan Technological issues being addressed • Scintillating oil studies: P=450 atm., T=0°C • Implosion studies at sea • Engineering studies of detector structure, deployment † hanohano- Hawaiian for distinguished * NOW 2006

  4. Hanohano- 10x “KamLAND” in ocean Construct in shipyard, fill/test in port, tow to site, and submerge to ~4 km NOW 2006

  5. Preliminary reference Earth model Knowledge of Earth interior from seismology Dziewonski and Anderson, Physics of the Earth and Planetary Interiors 25 (1981) 297-356. NOW 2006

  6. Bulk silicate Earth model Knowledge of Earth composition largely model dependent. “Standard Model” based on 3 meteorite samples. McDonough and Sun, Chemical Geology120 (1995) 223-253. NOW 2006

  7. Terrestrial heat flow: 31-44 TW Present controversy over hydrothermal flow Pollack, Hurter, and Johnson, Reviews of Geophysics31(3)(1993)267-280. Hofmeister and Criss, Tectonophysics395 (2005) 159-177. NOW 2006

  8. Geo-neutrinos- parent spectrum thorium chain uranium chain prompt Threshold for Reines and Cowan coincidence technique No direction or K neutrinos yet delayed NOW 2006

  9. Predicted geo-neutrino signal Hanohano SNO+ Borexino KamLAND F. Mantovani et al., Phys. Rev. D 69 (2004) 013001. Crust dominates on continents Mantle dominates in ocean Simulated event source distribution Signal mostly from <500 km NOW 2006

  10. Geo-ν + background spectra Background manageable μ± μ± Cosmic ray muons spallation products Target Volume Radioactive materials fastneutrons alpha source NOW 2006

  11. Hanohano: mantle measurement 1 year of Hanohano 15 years of SNO+ 48 years of Borexino NOW 2006

  12. Hanohano: mantle measurement 20% in 1 year Mantle (ev / 10 kT-y) Hanohano has ultimate sensitivity of <10%. Continental detectors cannot measure the mantle flux to better than 50%. Limiting factor 20% systematic uncertainty in U/Th content. NOW 2006

  13. Earth Th/U ratio measurement Statistical uncertainties only; includes reactors NOW 2006

  14. Anti-neutrinos from the core? Herndon hypothesis- natural fission reactor in core of Earth P=1-10 TW Controversial but not ruled out Geo-reactor hypothesis Herndon, Proc. Nat. Acad. Sci.93 (1996) 646. Hollenbach and Herndon, Proc. Nat. Acad. Sci.98 (2001) 11085. NOW 2006

  15. Geo-reactor search Geo-reactor power (TW) Power upper limit ~few TW needed to drive geomagnetic field 1 year run time- statistical uncertainties only NOW 2006

  16. 3-ν mixing: Reactor neutrinos Pee=1-{cos4(θ13)sin2(2θ12)sin2(Δm221L/4E) +cos2(θ12)sin2(2θ13)sin2(Δm231L/4E) +sin2(θ12)sin2(2θ13)sin2(Δm232L/4E)} Each amplitude cycles with own frequency • ½-cycle measurements • mixing angles, mass-squared differences • Multi-cycle measurements • Mixing angles, mass-squared differences • Potential for mass hierarchy NOW 2006

  17. Reactor ν mixing parameters: present knowledge • KamLAND combined analysis: tan2(θ12)=0.40(+0.10/–0.07) Δm221=(7.9±0.7)×10-5 eV2 Araki et al., Phys. Rev. Lett. 94 (2005) 081801. • CHOOZ limit: sin2(2θ13) ≤ 0.20 Apollonio et al., Eur. Phys. J. C27 (2003) 331-374. • SuperK and K2K: Δm231=(2.5±0.5)×10-3 eV2 Ashie et al., Phys. Rev. D64 (2005) 112005 Aliu et al., Phys. Rev. Lett. 94 (2005) 081802 NOW 2006

  18. νe flux measurement uncertainty • Flux from distant, extended source like Earth or sun is fully mixed • P(νe→νe) =1-0.5{cos4(θ13)sin2(2θ12)+sin2(2θ13)} =0.592 (+0.035/-0.091) Lower value for maximum angles Upper value for minimum angles • Φsource=Φdetector/P(νe→νe) Uncertainty is +15%/-6% NOW 2006

  19. Suggested ½-cycle θ12 measurement • Reactor experiment- νe point source • P(νe→νe)≈1-sin2(2θ12)sin2(Δm221L/4E) • 60 GW·kT·y exposure at 50-70 km • ~4% systematic error from near detector • sin2(θ12) measured with ~2% uncertainty Bandyopadhyay et al., Phys. Rev. D67 (2003) 113011. Minakata et al., hep-ph/0407326 Bandyopadhyay et al., hep-ph/0410283 NOW 2006

  20. Proposed ½-cycle θ13 measurements • Reactor experiment- νe point source • P(νe→νe)≈1-sin2(2θ13)sin2(Δm231L/4E) • Double Chooz, Daya Bay, Reno- measure θ13 with “identical” near/far detector pair • sin2(2θ13)≤0.03-0.01 in few years • Solar and matter insensitive • Challenging systematics Mikaelyan and Sinev, Phys. Atom. Nucl.62 (1999) 2008-2012. Anderson et al., hep-ex/0402041 NOW 2006

  21. Reactor antineutrino spectra- 50 km Plots by jgl no oscillation no oscillation Distance/energy, L/E Energy, E oscillations oscillations Neutrino energy (MeV) L/E (km/MeV) 1,2 oscillations with sin2(2θ12)=0.82 and Δm221=7.9x10-5eV2 1,3 oscillations with sin2(2θ13)=0.10 andΔm231=2.5x10-3 eV2 NOW 2006

  22. Fourier Transform on L/E to Δm2 Plots by jgl Fourier Power, Log Scale Δm232 < Δm231 normalhierarchy Peak due to nonzero θ13 Spectrum w/ θ13=0 Δm2 (x10-2 eV2) Preliminary- 10 kt-y exposure at 50 km range sin2(2θ13)≥0.05 Δm231=0.0025 eV2 to % level Learned, Pakvasa, Svoboda, SD preprint in preparation Δm2/eV2 Includes energy smearing- 3.5%/√E NOW 2006

  23. Neutrino mass hierarchy- reactor neutrinos m3 m2 m2 m1 m1 mass m3 Exposure and energy resolution are critical for this determination are currently under study normal inverted |Δm231| > |Δm232| |Δm231| < |Δm232| Δm232≈ (1.00 ± 0.03) Δm231 Petcov and Piai, Phys. Lett. B533 (2001) 94-106. NOW 2006

  24. Hanohano- candidate reactor sites San Onofre- ~6 GWth Maanshan- ~5 GWth NOW 2006

  25. Hanohano- 10 kT-y exposure • Neutrino Geophysics- near Hawaii • Mantle flux U/Th geo-neutrinos to ~25% • Measure Th/U ratio to ~20% • Rule out geo-reactor of P>0.3 TW • Neutrino Oscillation Physics- ~60 km by reactor • Measure sin2 (θ12) to few % w/ standard ½-cycle • Measure sin2(2θ13) down to ~0.05 w/ multi-cycle • Δm231 at percent level w/ multi-cycle • potential for mass hierarchy if θ13>0 without near detector; insensitive to background, systematics; complimentary to Minos, Nova NOW 2006

  26. Conclusion • Hanohano • 10 kT deep ocean anti-neutrino observatory • Movable for multi-disciplinary science • Neutrino geophysics • Neutrino oscillation physics • Under development at Hawaii; continuing funding from U.S. Department of Defense • 1st collaboration meeting 3/07 Interested? sdye@phys.hawaii.edu NOW 2006