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Hanohano

Hanohano. Mikhail Batygov, University of Hawaii, October 4, 2007, Hamamatsu, Japan, NNN’07. Overview of the project. Dual goal of the project Fundamental physics, esp.  oscillation studies Terrestrial antineutrinos Special advantages Reduced sensitivity to systematics

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Hanohano

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  1. Hanohano Mikhail Batygov, University of Hawaii, October 4, 2007, Hamamatsu, Japan, NNN’07

  2. Overview of the project • Dual goal of the project • Fundamental physics, esp.  oscillation studies • Terrestrial antineutrinos • Special advantages • Reduced sensitivity to systematics • Big size and low energy threshold • Variable baseline possible • Additional studies • Nucleon decay, possibly incl. SUSY favored kaon mode • Supernova detection • Relic SN neutrinos

  3. Oscillation Parameters: present • KamLAND (with SNO) analysis: tan2(θ12)=0.40(+0.10/–0.07) Δm221=(7.9+0.4/-0.35)×10-5 eV2 Araki et al., Phys. Rev. Lett. 94 (2005) 081801. (improved in 2007) • SuperK, K2K, MINOS: 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 (improved in 2007) • CHOOZ limit: sin2(2θ13) ≤ 0.20 Apollonio et al., Eur. Phys. J. C27 (2003) 331-374.

  4. Oscillation parameters to be measured 2 mass diffs, 3 angles, 1 CP phase • Precision measurement of mixing parameters needed • World effort to determine θ13 (=θ31) • Determination of mass hierarchy

  5. 12 precise measurement (2 mixing) • 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 Ideal spot Bandyopadhyay et al., Phys. Rev. D67 (2003) 113011. Minakata et al., hep-ph/0407326 Bandyopadhyay et al., hep-ph/0410283

  6. 3- mixing Pee=1-{ cos4(θ13) sin2(2θ12) [1-cos(Δm212L/2E)] + cos2(θ12) sin2(2θ13) [1-cos(Δm213L/2E)] + sin2(θ12) sin2(2θ13) [1-cos(Δm223L/2E)]}/2 • Survival probability: 3 oscillating terms each cycling in L/E space (~t) with own “periodicity” (Δm2~ω) • Amplitude ratios ~13.5 : 2.5 : 1.0 • Oscillation lengths ~110 km (Δm212) and ~4 km (Δm213~Δm223) at reactor peak ~3.5 MeV Two possible approaches: • ½-cycle measurements can yield • Mixing angles, mass-squared differences • Less statistical uncertainty for same parameter and detector • Multi-cycle measurements can yield • Mixing angles, precise mass-squared differences • Mass hierarchy • Less sensitive to systematic errors

  7. Reactor νe Spectra at 50 km invites use of Fourier Transforms Distance/energy, L/E Energy, E no oscillation no oscillation > 15 cycles 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

  8. Fourier Transform on L/E to Δm2 Peak profile versus distance Fourier Power, Log Scale Δm232 < Δm231 normalhierarchy E smearing 0.0025 eV2 peak due to nonzero θ13 50 km Spectrum w/ θ13=0 Fewer cycles Δm2 (x10-2 eV2) Preliminary- 50 kt-y exposure at 50 km range sin2(2θ13)≥0.02 Δm231=0.0025 eV2 to 1% level Learned, Dye,Pakvasa, Svoboda hep-ex/0612022 Δm2/eV2 Includes energy smearing

  9. Measure Δm231 by Fourier Transform & Determine νMass Hierarchy inverted normal Δm231 > Δm232 |Δm231| < |Δm232| Determination at ~50 km range sin2(2θ13)≥0.05 and 10 kt-y sin2(2θ13)≥0.02 and 100 kt-y θ12<π/4! Plot by jgl Δm2 (x10-2 eV2) Learned, Dye, Pakvasa, and Svoboda, hep-ex/0612022

  10. Hierarchy Determination Ideal Case with 10 kiloton Detector, 1 year off San Onofre Distance variation: 30, 40, 50, 60 km Hierarchy tests employing Matched filter technique, for Both normal and inverted hierarchy on each of 1000 simulated one year experiments using 10 kiloton detector. Inverted hierarchy Inv. Norm. Sin22θ13 Variation: 0.02 – 0.2 sin22 = 0.02 Normal Hierarchy 30 km 100 kt-yrs separates even at 0.02 Sensitive to energy resolution: Simulation for 3%/sqrt(E) 0.2 60 km

  11. Effect of Energy Resolution • Uses the difference in spectra • Efficiency depends heavily on energy resolution Perfect E resolution E = 6%*sqrt(Evis) E, MeV E, MeV

  12. Estimation of the statistical significance • Thousands of events necessary for reliable discrimination – big detector needed • Longer baselines more sensitive to energy resolution; may be beneficial to adjust for actual detector performance Neutrino events to 1  CL < 3%: desirable but maybe unrealistic E resolution KamLAND: 0.065 MeV0.5 Detector energy resolution, MeV0.5

  13. Big picture questions in Earth Science • What drives plate tectonics? • What is the Earth’s energy budget? • What is the Th & U conc. of the Earth? • Energy source driving the Geodynamo? Geo- reactor?

  14. Earth’s Total Heat Flow • Conductive heat flow measured from bore-hole temperature gradient and conductivity Data sources Total heat flow Conventional view 441 TW Challenged recently 311 TW - ? What is the origin of the heat?

  15. Detectable >1.8 MeV n p + e- + ne Radiogenic heat and geo-neutrinos 40K-decay modes Th-decay chain 238U (“Radium”)-decay chain 2 more decay chains: 235U “Actinium” – no -decays with sufficient energy “Neptunium” – extinct by now

  16. Urey Ratio and Mantle Convection Models • Mantle convection models typically assume: mantleUrey ratio: 0.4 to 1.0, generally ~0.7 • Geochemical models predict: Urey ratio 0.4 to 0.5. radioactive heat production Urey ratio = heat loss

  17. Discrepancies? • Est. total heat flow, 44 or 31TW est. radiogenic heat production 16TW or 31TW • Where are the problems? • Mantle convection models? • Total heat flow estimates? • Estimates of radiogenic heat production rate? • Geoneutrino measurements can constrain the planetary radiogenic heat production.

  18. U and Th Distributionin the Earth • U and Th are thought to be absent from the core and present in the mantle and crust. • Core: Fe-Ni metal alloy • Crust and mantle: silicates • U and Th concentrations are the highest in the continental crust. • Continents formed by melting of the mantle. • U and Th prefer to enter the melt phase • Continental crust: insignificant in terms of mass but major reservoir for U, Th, K.

  19. Two types of crust: Oceanic & Continental Oceanic crust: single stage melting of the mantle Continental crust: multi-stage melting processes Compositionally distinct

  20. Predicted Geoneutrino Flux Continental detectors dominated by continental crust geo-neutrinos Oceanic detectors can probe the U/Th contents of the mantle Reactor Flux - irreducible background Geoneutrino flux determinations -continental (DUSEL, SNO+, LENA) -oceanic (Hanohano)

  21. Current status of geo-neutrino studies • 2005: KamLAND detected terrestrial antineutrinos • Result consistent with wide range of geological models; most consistent with 16 TW radiogenic flux • 2007: KamLAND updated geo-neutrino result • Still no reasonable models can be ruled out • KamLAND limited by reactor background; future geo-neutrino detector must be built further from reactors

  22. Requirements to the detector • Baseline on the order of 50 km; better variable for different studies • Big number of events (large detector) • For Hierarchy and m213/23: • Good to excellent energy resolution • sin2(213)  0 • No full or nearly full mixing in 12 (almost assured by SNO and KamLAND) • For Geo-neutrinos: ability to “switch off” reactor background • To probe the geo-neutrino flux from the mantle: ocean based

  23. Anti-Neutrino Detection mechanism: inverse  Key: 2 flashes, close in space and time, 2nd of known energy, eliminate background Production in reactors and natural decays Detection Evis=Eν-0.8 MeV prompt delayed Evis=2.2 MeV • Standard inverse β-decay coincidence • Eν > 1.8 MeV • Rate and precise spectrum; no direction Reines & Cowan

  24. Hanohano: engineering studies Makai Ocean Engineering • Studied vessel design up to 100 kilotons, based upon cost, stability, and construction ease. • Construct in shipyard • Fill/test in port • Tow to site, can traverse Panama Canal • Deploy ~4-5 km depth • Recover, repair or relocate, and redeploy Barge 112 m long x 23.3 wide Deployment Sketch Descent/ascent 39 min

  25. Addressing Technology Issues 20m x 35m fiducial vol. • Scintillating oil studies in lab • P=450 atm, T=0°C • Testing PC, PXE, LAB and dodecane • No problems so far, LAB (Linear AlkylBenzene) favorite… optimization underway • Implosion studies • Design with energy absorption • Computer modeling & at sea • No stoppers • Power and comm, no problems • PMT housing: Benthos glass boxes • Optical detector, prototypes OK • Need second round design 1 m oil 2m pure water

  26. Current status • Several workshops held (’04, ’05, ’06) and ideas developed • Study funds provided preliminary engineering and physics feasibility report (11/06) • Strongly growing interest in geology community • Work proceeding and collaboration in formation • Upcoming workshops in Washington DC (10/07) and Paris (12/07) for reactor monitoring • Funding request for next stage (’06) in motion • Ancillary proposals and computer studies continue

  27. Summary • Better precision for sin2(212), sin2(213) – to 2% possible with Hanohano • If sin2(213)  0: high precision measurement of m213, m223, and even mass hierarchy possible with the same detector; for sin2212 = 0.05, m213, m223 – to 1-2% (0.025-0.05x10-3 eV2) • Big ocean based detector is perfect for oscillation studies (adjustable baseline, high accuracy) and for studying geo-neutrinos, especially from the mantle • Geo-reactor hypothesis can be ultimately tested • Additional physics measurements achievable to higher precision than achieved before

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