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 Big size and low energy threshold Variable baseline possible

Additional studies Nucleon decay, possibly incl. SUSY favored kaon mode Supernova detection Relic SN neutrinos

Oscillation Parameters: present

KamLAND (with SNO) analysis:tan2(θ12)=0.40(+0.10/–0.07)Δm2

21=(7.9+0.4/-0.35)×10-5 eV2

Araki et al., Phys. Rev. Lett. 94 (2005) 081801. (improved in 2007)

SuperK, K2K, MINOS: Δm2

31=(2.5±0.5)×10-3 eV2

Ashie et al., Phys. Rev. D64 (2005) 112005Aliu et al., Phys. Rev. Lett. 94 (2005) 081802 (improved in 2007)

CHOOZ limit: sin2(2θ13) ≤ 0.20Apollonio et al., Eur. Phys. J. C27 (2003) 331-374.

Oscillation parameters to be measured

Precision measurement of mixing parameters needed

World effort to determine θ13 (= θ31)

Determination of mass hierarchy

2 mass diffs, 3 angles, 1 CP phase2 mass diffs, 3 angles, 1 CP phase

12 precise measurement (2 mixing)

Reactor experiment- ν e point source

P(νe→νe)≈1-sin2(2θ12)sin2(Δm2

21L/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/0407326Bandyopadhyay et al., hep-ph/0410283

Ideal spot

3- mixingPee=1-{ cos4(θ13) sin2(2θ12) [1-cos(Δm2

12L/2E)] + cos2(θ12) sin2(2θ13) [1-cos(Δm2

13L/2E)] + sin2(θ12) sin2(2θ13) [1-cos(Δm2

23L/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 (Δm2

12) and ~4 km (Δm213 ~ Δm2

23) 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

Reactor Reactor ννee Spectra at 50 Spectra at 50 kmkm

1,2 oscillations with sin2(2θ12)=0.82 and Δm2

21=7.9x10-5 eV2

1,3 oscillations with sin2(2θ13)=0.10 and

Δm231=2.5x10-3 eV2

no oscillation

oscillations

no oscillation

oscillations

Neutrino energy (MeV) L/E (km/MeV)

Distance/energy, Distance/energy, L/EL/E

Energy, EEnergy, E

> 15 cycles

invites use of Fourier Transforms

Fourier Transform on L/E to Fourier Transform on L/E to ΔΔmm22

Fourier Power, Log Scale

Spectrum w/ θ13=0

Δm2/eV2

Preliminary-50 kt-y exposure at 50 km range

sin2(2θ13)≥0.02 Δm2

31=0.0025 eV2 to 1% level

Learned, Dye,Pakvasa, Svoboda hep-ex/0612022

Δm232 < Δm2

31 normal hierarchy

Δm2 (x10-2 eV2)

0.0025 eV2 peak due to nonzero θ13

Includes energy smearing

Peak profile versus distance

E smearing

Fewer cycles

50 km

Measure Measure ΔΔmm223131 by Fourier by Fourier

Transform & Determine Transform & Determine νν Mass Mass HierarchyHierarchy

Determination at ~50 km range

sin2(2θ13)≥0.05 and 10 kt-y

sin2(2θ13)≥0.02 and 100 kt-yΔm2 (x10-2 eV2)Plot by jgl

Δm231 > Δm2

32 |Δm231| < |Δm2

32|

normalinverted

Learned, Dye, Pakvasa, and Svoboda, hep-ex/0612022

θ12<π/4!

Distance variation: 30, 40, 50, 60 km

Hierarchy DeterminationHierarchy DeterminationIdeal Case with 10 kiloton Detector, 1 year off San Onofre

Sin22θ13 Variation: 0.02 – 0.2

100 kt-yrs separates even at 0.02

Normal Hierarchy

Invertedhierarchy

Hierarchy tests employing Matched filter technique, for Both normal and inverted hierarchy on each of 1000 simulated one year experiments using 10 kiloton detector.

Sensitive to energy resolution: Simulation for 3%/sqrt(E)

30 km

60 km

sin22 = 0.02

0.2

Inv.

Norm.

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

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

Detector energy resolution, MeV0.5

Neu

trin

o ev

ents

to

1

CL

KamLAND: 0.065 MeV0.5

< 3%: desirable but maybe unrealistic E resolution

Big picture questions in Earth ScienceBig 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?

Data sources

Earth’s Total Heat FlowEarth’s Total Heat Flow

• Conductive heat flow measured from bore-hole temperature gradient and conductivity

Total heat flow Conventional view 44441 TW1 TW Challenged recently 31311 TW - ?1 TW - ?What is the origin of the heat?

Radiogenic heat and geo-Radiogenic heat and geo-neutrinosneutrinos

238U (“Radium”)-decay chain

Th-decay chain

40K-decay modes

n p + e- + e

Detectable>1.8 MeV

2 more decay chains:235U “Actinium” – no -decays with sufficient energy“Neptunium” – extinct by now

Mantle convection models typically assume:mantle Urey ratio: 0.4 to 1.0, generally ~0.7

Geochemical models predict: Urey ratio 0.4 to 0.5.

Urey Ratio and Urey Ratio and Mantle Convection Mantle Convection ModelsModels

Urey ratio =radioactive heat production

heat loss

Discrepancies?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.

U and Th DistributionU and Th Distributionin the Earthin 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 Continental crust: insignificant in terms of mass but major reservoir for U, Th, K.reservoir for U, Th, K.

Two types of crust: Oceanic & ContinentalTwo types of crust: Oceanic & Continental

Oceanic crust: single stage melting of the mantleContinental crust: multi-stage melting processes Compositionally distinct

Predicted Predicted Geoneutrino FluxGeoneutrino Flux

Geoneutrino flux determinations-continental (DUSEL, SNO+, LENA)-oceanic (Hanohano)

Reactor FluxReactor Flux - irreducible background

Continental detectors dominated by continental crust geo-neutrinosOceanic detectors can probe the U/Th contents of the mantle

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

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 m2

13/23: Good to excellent energy resolution sin2(213) 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

Anti-Neutrino Detection mechanism: inverse

Evis=Eν-0.8 MeVprompt

delayedEvis=2.2 MeV

• Standard inverse β-decay coincidence

• Eν > 1.8 MeV

• Rate and precise spectrum; no direction

Production in reactorsand natural decays

Detection

Key: 2 flashes, close in space and time, 2 flashes, close in space and time, 22ndnd of known energy, of known energy, eliminate backgroundeliminate background

Reines & Cowan

Deployment Sketch

Hanohano: Hanohano: engineering studiesengineering studies

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

Descent/ascent 39 min

Barge 112 m long x 23.3 wide

Makai Ocean Engineering

Addressing Technology Addressing Technology IssuesIssues

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

20m x 35mfiducial vol.

1 m oil

2m pure water

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

Summary Better precision for sin2(212), sin2(213) – to 2%

possible with Hanohano If sin2(213) 0: high precision measurement of

m213, m2

23, and even mass hierarchy possible with the same detector; for sin2212 = 0.05, m2

13, 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