Hawaii Anti-Neutrino Observatory

1
Hawaii Anti-Neutrino Observatory

• For the Hanohano collaboration
• Steve Dye
• University of Hawaii at Manoa
• and
• Hawaii Pacific University

2
Outline of Talk

• Objectives
• 15 measurement of mantle U/Th neutrinos (QUTh
  8 1 TW)
• Search for gt1TW geo-reactor
• Methods
• Big KamLAND in the deep ocean
• Conclusions

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Institutions and Personnel

• University of Hawaii at Manoa
• Steve Dye, Peter Grach, Gene Guillian,
• John Learned (PI), Jelena Maricic,
• Shige Matsuno, Sandip Pakvasa, Gary Varner,
• Mavourneen Wilcox
• Makai Ocean Engineering
• Tore Leraand, Joe Van Ryzin (PI)
• Others

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Funding and Support

• CEROS 1-year study funds
• Critical issues of deep ocean deployment
• Implosion of PMT modules
• Optical properties of scintillating oil
• Low power electronics
• Data transmission
• Detector design criteria
• Size and sensitivity
• UH Physics support infrastructure
• Center of Excellence for Research in Ocean
  Sciences

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Predicted Geo-neutrino Signal
(1032 proton-yrs 1 TNU 1.2 kT-y of KamLAND
oil)
F. Mantovani et al., Phys. Rev. D 69, 013001
(2004).
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Geo-neutrino sources

• Japan
• 13
• mantle crust
• Hawaii
• 31
• mantle crust

Plot courtesy of S. Enomoto
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Predicted Mantle-neutrino Signal in Scintillating
Oil
S F(TNU) x 0.85(kT/TNU)

• Raghavan et al. (1998)
• U(ppm) 0.01
• F(U) 7.3 TNU
• F(Th) 1.9 TNU
• F(tot) 9.2 TNU
• S 7.9 per kT-y

• Enomoto thesis (2005)
• U(ppm) 0.012
• F(U) 8.1 TNU
• F(Th) 2.2 TNU
• F(tot) 10.3 TNU
• S 8.8 per kT-y

S 7.9 per kT-y (Mantovani this workshop) S
8.5 per kT-y (Lisi this workshop)
Corrected for oscillation
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Geo-neutrino Signal
Geo-nu analysis
Reactor-nu analysis
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Geo-neutrino Signal plus Known Backgrounds
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Geo-neutrino Signal Background with Geo-reactor
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Significance and Signals

• Signal significance s S / v(SB)
• Mantle-neutrino signal
• 80 events per 10 kT-y (1.7ltE?(MeV)lt3.4)
• 1 TW Geo-reactor signal
• 38 events per 10 kT-y (3.4lt E?(MeV)lt9.3)
• Set s 5 for discovery (Pgt99.99)
• s5 requires Blt20 events per 10 kT-y

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Geo-neutrino signature in Scintillating Oil
Scintillating oil viewed with PMTs measures
energy but not direction of geo-neutrino
p
Delayed signal Evis 2.2MeV ?t 200µs ?r 10cm

Geo-neutrino
?e from ß-decay on U/Th chain
?
Prompt signal EvisE?- En - 0.8 MeV
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Identified Backgrounds
µ
µ

• Secondary cosmic rays
• Fast neutrons
• Spallation- 9Li
• Dirty scintillating oil
• 13C(a,n)16O
• Impurities outside
• Accidental coincidences
• Antineutrinos
• Nuclear reactors
• Earths crust

Cosmic ray muons
Radioactive materials
Target Volume
spallation products
fast neutrons
alpha source
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Background Reduction

• Location, location, location
• Far from nuclear reactors and continental crust
• gt4000 m.w.e. overburden
• Clean, clean, clean
• lt 1/40 KamLAND 210Po level
• Radio-pure detector materials

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Backgrounds Mantle-neutrino measurement
1.7ltE?(MeV)lt3.4 Rate (10 kT-y)-1
9Li (4 km) 0 0
210Po 13 3
Accidentals (lt) 30 1
Known Reactors (lt) 14 1
Crust neutrinos 29 5
Total 86 5

• Scale KamLAND
• (Nature 436 2005)
• x 12 exposure
• 1/40 210Po
• Total expected 865
• Geo-reactor adds 19 events per TW

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Backgrounds Geo-reactor search

• Scale KamLAND (PRL 94 2005)
• x 13 exposure
• 1/40 210Po
• Rtarget 5m
• Total expected 362
• 1.2 TW discovery threshold

3.4ltE?(MeV)lt9.3 Rate (10 kT-y)-1
9Li (4 km) 4 1
210Po 3 2
Accidentals 1 0
Commercial Reactors 28 1
Total 36 2
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Site Selection
Many sites considered- best is same as DUMAND
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Hanohano
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Current Status

• Prototype electronics fabricated and tested- G.
  Varner, M. Wilcox
• Scintillating oil pressure tests in preparation-
  P. Grach
• Implosion tests next year
• Ocean demonstration of prototype detector to
  follow

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Electronics prototypes
PMT base
Digitizer
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Conclusions

• 10 kT-y exposure of Hanohano would
• Measure BSE mantle U/Th to 11
• Search for 1TW geo-reactor
• Hanohano in design stage
• 4 kT target volume KamLAND
• Deep ocean deployment for few years