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

9/14/06- S. Dye NOW 2006 1

Outline

• Neutrino Geophysics – U/Th mantle flux – Th/U ratio – Geo-reactor search • Neutrino Oscillation Physics – Mixing angles θ 12 and θ 13 – Mass squared difference Δm 2 31 – Mass hierarchy 9/14/06- S. Dye NOW 2006 2

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 9/14/06- S. Dye NOW 2006 3

Hanohano- 10x “KamLAND” in ocean

Construct in shipyard, fill/test in port, tow to site, and submerge to ~4 km

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Preliminary reference Earth model

Knowledge of Earth interior from seismology Dziewonski and Anderson, Physics of the Earth and Planetary Interiors 25 (1981) 297-356.

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Bulk silicate Earth model

Knowledge of Earth composition largely model dependent.

“Standard Model” based on 3 meteorite samples.

McDonough and Sun, Chemical Geology 120 (1995) 223-253.

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Terrestrial heat flow: 31-44 TW

Present controversy over hydrothermal flow Pollack, Hurter, and Johnson, Reviews of Geophysics 31(3) (1993) 267-280.

Hofmeister and Criss, Tectonophysics 395 (2005) 159-177.

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Geo-neutrinos- parent spectrum

Threshold for Reines and Cowan coincidence technique

No direction or K neutrinos yet

9/14/06- S. Dye NOW 2006 thorium chain uranium chain prompt delayed 8

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

9/14/06- S. Dye NOW 2006 Simulated event source distribution Signal mostly from <500 km 9

Geo-ν + background spectra

Background manageable

μ ±

Cosmic ray muons

μ ±

Target Volume spallation products fast neutrons alpha source Radioactive materials

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Hanohano: mantle measurement

1 year of Hanohano 15 years of SNO+

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Hanohano: mantle measurement

400 300 200 100 20% in 1 year 0 -100 KLND SNO+ Bxno Hano -200 -300 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.

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Earth Th/U ratio measurement

Project

crust type

KamLAND

island arc

Borexino

continental

SNO+

continental

Hanohano

oceanic

δR/R (1 yr exposure) 2.0

1.1

0.62

0.20

Th/U (1 yr exposure) 4 ± 8 4 ± 4 3.9 ± 2.4

3.9 ± 0.8

Years to 10% measurement 390 120 39 3.9

Statistical uncertainties only; includes reactors

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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.

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Geo-reactor search

10 5 25 20 15

Power upper limit

0 KL Bxno SNO+ Hano ~few TW needed to drive geomagnetic field

Project

crust type

Power limit 99% CL (TW) 5σ discovery power (TW) KamLAND

island arc

Borexino

continental

SNO+

continental

Hanohano

oceanic

22 12 9 0.3

51 43 22 1.0

1 year run time statistical uncertainties only

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3-ν mixing: Reactor neutrinos

P ee = 1-{cos 4 (θ 13 )sin 2 (2θ 12 )sin 2 (Δm 2 21 L/4E) + + cos 2 (θ 12 )sin 2 (2θ 13 )sin 2 (Δm 2 31 L/4E) sin 2 (θ 12 )sin 2 (2θ 13 )sin 2 (Δm 2 32 L/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 9/14/06- S. Dye NOW 2006 16

Reactor ν mixing parameters: present knowledge

• KamLAND combined analysis:

tan 2 (θ 12 ) = 0.40( + 0.10/ – 0.07) Δm 2 21 =(7.9

± 0.7) × 10 -5 eV 2

Araki et al., Phys. Rev. Lett. 94 (2005) 081801.

• CHOOZ limit: sin

2 (2θ 13 ) ≤ 0.20

Apollonio et al., Eur. Phys. J. C27 (2003) 331-374.

• SuperK and K2K:

Δm 2 31 =(2.5

± 0.5) × 10 -3 eV 2

Ashie et al., Phys. Rev. D64 (2005) 112005 Aliu et al., Phys. Rev. Lett. 94 (2005) 081802 9/14/06- S. Dye NOW 2006 17

ν

e

flux measurement uncertainty

• Flux from distant, extended source like Earth or sun is fully mixed • P(ν e → ν e ) = 1-0.5{cos 4 (θ 13 )sin 2 (2θ 12 ) + sin 2 (2θ 13 )} = 0.592 ( + 0.035/-0.091) Lower value for maximum angles Upper value for minimum angles • Φ source = Φ detector /P(ν e → ν e ) Uncertainty is +15%/-6% 9/14/06- S. Dye NOW 2006 18

Suggested ½-cycle θ

12

measurement

• Reactor experiment- ν e point source • P(ν e → ν e ) ≈ 1-sin 2 (2θ 12 )sin 2 (Δm 2 21 L/4E) • 60 GW·kT·y exposure at 50-70 km – ~4% systematic error from near detector – sin 2 (θ 12 ) measured with ~2% uncertainty Bandyopadhyay et al., Phys. Rev. D67 (2003) 113011.

Minakata et al., hep-ph/0407326 Bandyopadhyay et al., hep-ph/0410283 9/14/06- S. Dye NOW 2006 19

Proposed ½-cycle θ

13

measurements

• Reactor experiment- ν e point source • P(ν θ 13 e → – sin 2 ν e (2θ ) ≈ 13 ) 1-sin ≤ 2 (2θ 13 )sin 2 (Δm – Solar and matter insensitive 2 31 L/4E) • Double Chooz, Daya Bay, Reno- measure with “identical” near/far detector pair 0.03-0.01 in few years – Challenging systematics Mikaelyan and Sinev, Phys. Atom. Nucl. 62 (1999) 2008-2012.

Anderson et al., hep-ex/0402041 9/14/06- S. Dye NOW 2006 20

Reactor antineutrino spectra- 50 km

Plots by jgl no oscillation Energy, E no oscillation Distance/energy, L/E oscillations oscillations Neutrino energy (MeV) L/E (km/MeV)

1,2 oscillations with sin 2 (2θ 12 )=0.82 and Δm 2 21 =7.9x10

-5 1,3 oscillations with sin 2 (2θ 13 )=0.10 and Δm 2 31 =2.5x10

-3

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eV 2 eV 2

21

Fourier Transform on L/E to Δm

2 Plots by jgl Fourier Power, Log Scale Δm 2 32 < Δm 2 31 normal hierarchy Peak due to nonzero θ 13 Spectrum w/ θ 13 =0

Δm 2 (x10 -2 eV 2 )

Δm 2 /eV 2 Includes energy smearing- 3.5%/ √E 9/14/06- S. Dye NOW 2006

Preliminary-

10 kt-y exposure at 50 km range sin 2 (2 θ 13 )≥0.05

Δm 2 31 =0.0025 eV 2 Learned, Pakvasa, Svoboda, SD preprint in

preparation

to % level 22

Neutrino mass hierarchy- reactor neutrinos m 3 m 2 m 1 normal

| Δm 2 31 | > | Δm 2 32 |

m 2 m 1 m 3 inverted

| Δm 2 31 | < | Δm 2 32 | Exposure and energy resolution are critical for this determination are currently under study

Δm 2 32 ≈ (1.00 ± 0.03) Δm 2 31 Petcov and Piai, Phys. Lett. B533 (2001) 94-106.

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Hanohano candidate reactor sites

San Onofre- ~6 GW th Maanshan- ~5 GW th 9/14/06- S. Dye NOW 2006 24

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 sin 2 (θ 12 ) to few % w/ standard ½-cycle – Measure sin 2 (2θ 13 ) down to ~ 0.05 w/ multi-cycle – Δm 2 31 at percent level w/ multi-cycle – potential for mass hierarchy if θ complimentary to Minos, Nova 13 >0 without near detector; insensitive to background, systematics; 9/14/06- S. Dye NOW 2006 25

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 – 1 st collaboration meeting 3/07 Interested? [email protected]

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