Hanohano

1
Hanohano

• Mikhail Batygov,
• University of Hawaii,
• October 4, 2007, Hamamatsu, Japan, NNN07

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(?12)0.40(0.10/0.07)
• ?m221(7.90.4/-0.35)10-5 eV2
• Araki et al., Phys. Rev. Lett. 94 (2005) 081801.
  (improved in 2007)
• SuperK, K2K, MINOS
• ?m231(2.50.5)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(2?13) 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 ?13 ( ?31)
• Determination of mass hierarchy

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?12 precise measurement (2? mixing)

• Reactor experiment- ? e point source
• P(?e??e)1-sin2(2?12)sin2(?m221L/4E)
• 60 GWkty exposure at 50-70 km
• 4 systematic error
• from near detector
• sin2(?12) measured with
• 2 uncertainty

Ideal spot
Bandyopadhyay et al., Phys. Rev. D67 (2003)
113011. Minakata et al., hep-ph/0407326 Bandyopadh
yay et al., hep-ph/0410283
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3-? mixing

• Pee1- cos4(?13) sin2(2?12) 1-cos(?m212L/2E)
• cos2(?12) sin2(2?13)
  1-cos(?m213L/2E)
• sin2(?12) sin2(2?13)
  1-cos(?m223L/2E)/2
• Survival probability 3 oscillating terms each
  cycling in L/E space (t) with own periodicity
  (?m2?)
• Amplitude ratios 13.5 2.5 1.0
• Oscillation lengths 110 km (?m212) and 4 km
  (?m213 ?m223) 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 ?e Spectra at 50 km
invites use of Fourier Transforms
Distance/energy, L/E
Energy, E
no oscillation
no oscillation
gt 15 cycles
oscillations
oscillations
Neutrino energy (MeV)
L/E (km/MeV)
1,2 oscillations with sin2(2?12)0.82 and
?m2217.9x10-5 eV2 1,3 oscillations with
sin2(2?13)0.10 and ?m2312.5x10-3 eV2
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Fourier Transform on L/E to ?m2
Peak profile versus distance
Fourier Power, Log Scale
?m232 lt ?m231 normal hierarchy
E smearing
0.0025 eV2 peak due to nonzero ?13
50 km
Spectrum w/ ?130
Fewer cycles
?m2 (x10-2 eV2)
Preliminary- 50 kt-y exposure at 50 km
range sin2(2?13)0.02 ?m2310.0025 eV2 to 1
level Learned, Dye,Pakvasa, Svoboda
hep-ex/0612022
?m2/eV2
Includes energy smearing
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Measure ?m231 by Fourier Transform Determine ?
Mass Hierarchy
inverted
normal
?m231 gt ?m232
?m231 lt ?m232
Determination at 50 km range sin2(2?13)0.05
and 10 kt-y sin2(2?13)0.02 and 100 kt-y
?12ltp/4!
Plot by jgl
?m2 (x10-2 eV2)
Learned, Dye, Pakvasa, and Svoboda, hep-ex/0612022
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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.
Sin22?13 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
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Effect of Energy Resolution
Perfect E resolution
?E 6sqrt(Evis)
E?, MeV
E?, MeV

• Uses the difference in spectra
• Efficiency depends heavily on energy resolution

12
Estimation of the statistical significance
Neutrino events to 1 ? CL
lt 3 desirable but maybe unrealistic E resolution
KamLAND 0.065 MeV0.5
Detector energy resolution, MeV0.5

• 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

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Big picture questions in Earth Science

• What drives plate tectonics?
• What is the Earths energy budget?
• What is the Th U conc. of the Earth?
• Energy source driving the Geodynamo? Geo-
  reactor?

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Earths 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?
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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
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Urey Ratio and Mantle Convection Models
radioactive heat production
Urey ratio
heat loss

• 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.

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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.

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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.

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Two types of crust Oceanic Continental
Oceanic crust single stage melting of the
mantle Continental crust multi-stage melting
processes
Compositionally distinct
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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)
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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

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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

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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
EvisE?-0.8 MeV prompt
delayed Evis2.2 MeV

• Standard inverse ß-decay coincidence
• E? gt 1.8 MeV
• Rate and precise spectrum no direction

Reines Cowan
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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
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Addressing Technology Issues
20m x 35m fiducial vol.

• Scintillating oil studies in lab
• P450 atm, T0C
• 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
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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

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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