Anti/Neutrino/Geoneutrino detection - Interdisciplinary science

KamLAND Borexino

Physics Astronomy Geology National Security

SONGS Hanohano

Mobile detector

REFRACTORY ELEMENTS

Detecting Geoneutrino in the Earth

b

decay

Nature 436 , 499-503 (28 July 2005)  Detecting Electron Antineutrinos from inverse beta -decay 

e



p



n



e



2 flashes close in space and time Rejects most backgrounds

MeV-Scale Electron Anti-Neutrino Detection

Production in reactors and natural decays

Key: 2 flashes, close in space and time, 2 nd of known energy, eliminate background

Detection E vis =E ν -0.8 MeV prompt

Reines & Cowan

delayed E vis =2.2 MeV • Standard inverse β-decay coincidence • E ν > 1.8 MeV • Rate and spectrum - no direction

“Neutrino” Sources and Flux

Nuclear Reactor Flux Nuclear Reactors All Stars (Sun) Particle Accelerators Cosmic Rays Natural Radioactivity Supernova Black Holes/Quasars Predicted Geoneutrino Flux Big Bang

IceCube

Current Neutrino Detectors

KAMLAND SONGS ANITA v Source:

Galactic Nuclei

Detector Type:

Cherenkov

v Source:

Geo and Nuclear

Detector Type:

Scintillation

v Source:

Nuclear

Detector Type:

Scintillation

v Source:

Galactic Nuclei

Detector Type:

Cherenkov

6 * typical flux 10 6



cm 2 s -1 typical flux 2 * 10 20



s -1

Φ(E) Geo ν N(E) Reactor Antineutrinos σ(E) Oscillated spectra (Abe et al., 2008) ε= 1

Kamioka Gran Sasso Sudbury Homestake Baksan Pyhasalmi Hawaii

S. Enomoto,

Neutrino Sciences 2007

arXiv:0912.2775

Hanohano

An experiment with joint interests in Physics, Geology, and Security

- multiple deployments - deep water cosmic shield - control-able L/E detection Deployment Sketch

A Deep Ocean



e

Electron Anti-Neutrino Observatory

Descent/ascent 39 min

½-cycle

θ

12

(=

θ

21

) measurement

with Hanohano • Reactor experiment-

ν

e point source • P( ν e → ν e ) ≈ 1-sin 2 (2

θ

12 )sin 2 ( Δ

m

2 21

L

/4

E

) • 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 oscillation maximum at ~ 50-60 km

3-

ν

Mixing: Reactor Neutrinos

P ee = 1-{ cos 4 ( θ 13 ) sin 2 (2 θ 12 ) [1-cos( Δm 2

12

L/2E)] + cos 2 ( θ 12 ) sin 2 (2 θ 13 ) [1-cos( Δm 2

13

L/2E)] + sin 2 ( θ 12 ) sin 2 (2 θ 13 ) [1-cos( Δm 2

23

L/2E)]}/2 mixing angles mass diffs

}

wavelength close, 3% • Survival probability: 3 oscillating terms each cycling in L/E space (~t) with own “periodicity” (Δm 2 ~ ω) – Amplitude ratios ~13.5 : 2.5 : 1.0

– Oscillation lengths ~110 km (Δm 2 12 ) and ~4 km ( Δm 2 13 Δm 2 23 ) at reactor peak ~3.5 MeV ~ • ½-cycle measurements can yield – Mixing angles, mass-squared differences • Multi-cycle measurements can yield – Mixing angles, precise mass-squared differences – Mass hierarchy –

Less sensitivity to systematic errors

Candidate Off-shore Sites

San Onofre, California- ~6 GW th Maanshan, Taiwan- ~5 GW th

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

• • • • •

Addressing Technology Issues Scintillating oil studies in lab

– – –

P = 450 atm, T = 0

°

C Testing PC, PXE, LAB and dodecane No problems so far, LAB favorite… optimization needed Implosion studies

– – –

Design with energy absorption Computer modeling & at sea No stoppers Power and comm, no problems Optical detector, prototypes OK Need second round design Implosion signals from empty sphere and a sphere with 30% volume filled with foam

-0.4

-0.6

-0.8

-1 1 0.8

0.6

0.4

0.2

0 0.0035

0.0045

0.0055

0.0065

0.0075

0.0085

0.0095

Time (seconds)

30% Foam filled (4105m) Empty (4280m) 20m x 35m fiducial vol.

1 m oil 2m pure water

Summary of Expected Results Hanohano- 10 kt-yr Exposure

•

Neutrino Geophysics- near Hawaii

–

Mantle flux U geoneutrinos to ~10%

–

Heat flux ~15%

–

Measure Th/U ratio to ~20%

–

Rule out geo-reactor if P > 0.3 TW

•

There is also plenty of Neutrino Physics..

•

And much astrophysics and nucleon decay too….

Physics and Astrophysics

Big liquid scintillation detectors

• Long base line neutrino beam excellent flavor discrimination • • Nucleon Decay: SUSY-favored kaon modes • Supernova Detection: special

ν e

ability • Relic SN Neutrinos

Long list of ancillary, non interfering science, with strong discovery potential

Natural vs Man-made



signal U geoneutrinos Th geoneutrinos 6TW georeactor Commercial reactors

Reactor and Earth Signal

Geoneutrinos KamLAND Reactor Background with oscillation • KamLAND was designed to measure reactor antineutrinos.

• Reactor antineutrinos are the most significant contributor to the total signal.

Geoneutrinos

20% K-decay chain

238 U, 232 Th and 40 K generate 8TW, 8TW, and 3TW of radiogenic heat in the Earth

Th-decay chain 1% U-decay chain 46% 31%

Beta decays produce electron antineutrinos (aka “geo-neutrinos”)

n p + e +



e

238 U 1 α, 1β 234 Pa ν e 2.3 MeV

Terrestrial Antineutrinos

ν e + p + → n + e + 1.8 MeV Energy Threshold 238 U 232 Th 40 K 232 Th 1 α, 1β ν e 2.1 MeV 228 Ac 5 α, 2β 214 Bi ν e 3.3 MeV 2 α, 3β 206 Pb 4 α, 2β ν e 2.3 MeV 212 Bi 40 K 1 β 40 Ca LAr potential for K geonus D. Cline 1 α, 1β Terrestrial antineutrinos from uranium and thorium are detectable 208 Pb

Time Line 1897 Structure of EARTH Rock surrounding metal Emil Wiechert 1915 1925 1935 1970 PLATE TECTONICS today

AGE OF THE EARTH

thermal evolution

Lord Kelvin 1862

Conductive cooling of a

solid

planet

Age of Earth ~100 My

Heat loss depends on thermal boundary layer thickness d d d = √ pk t k

=35 km 2 /My

John Perry 1895

Conductive cooling of a planet with a

convecting

interior

Age of Earth ~1 Gy Ernest Rutherford 1904

“… Kelvin had limited the age of the earth provided that no new source of heat was discovered . … what we are considering tonight,

radium

!" Rutherford fondly recalled, "Behold! the old boy beamed upon me.” (

Kelvin was in the audience

)

5 Big Questions:

- What is the Planetary K/U ratio?

planetary volatility curve

- Radiogenic contribution to heat flow?

secular cooling

- Distribution of reservoirs in mantle?

whole vs layered convection

- Radiogenic elements in the core??

Earth energy budget

- Nature of the Core-Mantle Boundary?

hidden reservoirs

Plate Tectonics, Convection and Cooling of the Mantle

Nuclear power drives the Earth’s engine!

Two types of crust: Oceanic & Continental Old (>2Ga) Young (<0.2 Ga) Oceanic crust

: single stage melting of the mantle

Continental crust

: multi-stage melting processes Compositionally distinct

Oceanic crust <200 million years old

Continents up to 3500 million years old ages (Ga) <0.6

06.-2.6

>2.6

U in the Earth: “Differentiation”

Continental crust (<50%) Mantle (>50%)

~13 ng/g U in the Earth Metallic sphere (core) <<<1 ng/g U Silicate sphere 20 ng/g U Continental Crust 1000 ng/g U Mantle 10 ng/g U

Chromatographic separation Mantle melting & crust formation

Data sources Earth’s Total Surface Heat Flow

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

Total heat flow

Conventional view

46



3 TW

Challenger’s view

31



1 TW

after Jaupart et a 2008 Treatise of Geophysics

Urey Ratio and Mantle Convection Models

Urey ratio = radioactive heat production heat loss

• Mantle convection models typically assume: mantle Urey ratio: 0.4 to 1.0,

generally ~0.7

• Geochemical models predict: mantle Urey ratio ~

0.3

Factor of 2 discrepancy

Parameterized Convection Models

Thermal evolution of the mantle

Q



Ra

b ,

Q: heat flux, Ra: Rayleigh number,

b

: an amplifer - balance between viscosity and heat dissipation

•

Models with Ur



0.65

•

Schubert et al ‘80; Davies ‘80; Turcotte et al ‘01 Models with Ur



0.5

Jaupart et al ‘08; Korenaga ‘06; Grigne et al ‘05,’07

Mantle is depleted in some elements (e.g., Th & U) that are enriched in the continents.

- models of mantle convection and element distribution Th & U poor Th & U rich

Predicted Geoneutrino Flux Reactor Flux Reactor flux - vs geological background Geoneutrino flux determinations

-continental (KamLAND, Borexino, SNO+) -oceanic ? (Hanohano)

Geo-reactor ?

-- Hypothesized, a mass of uranium is located at or around the Earth core --Envisage a natural nuclear reactor producing up to 6TW of heat, which can power the Earths dynamo.

--Such phenomena could explain the anomalies observed in 3 He/ 4 He ratio.

TEST: directly observe the Earth’s neutrinos spectra from this reactor.

Plenty of suggestions for Geo-reactors deep inside the Earth

Based on: R. de Meijer & W. van Westrenen South African Journal of Science (2008)

Paramount Request

Detecting Potassium (K)



e (1) Significant for the Planetary budget of volatile element -- What did we inherit from our accretion disk?

(2) Fundamental to unraveling Mantle structure - 40 K controls mantle Ar inventory 40 K



40 Ar (EC) (3) Geophysics want K in core to power the Geodynamo?

- We don’t understand the energy source…

Large liquid scintillation detectors used for measuring the Earth antineutrino flux Borexino, Italy (0.6kt) SNO+, Canada (1kt) KamLAND, Japan (1kt) Hanohano, ocean-based (10kt)

Geo-neutrino Sensitivity

Detector KamLAND Borexino SNO+ DUSEL Baksan LENA Hanohano x10 32 p + 0.62

0.18

0.57

36.7

4.0

36.7

7.34

Event rates

n = g + r g = c + m ρ = Th/U

Reference flux from Mantovani et al. 2004 hep-ph/0309013 Dye 2009 arXiv:0912.2775

w/ 50 kT-yr measure: Geo-nus to ~5% Crustal nus to ~6% Th/U to ~20%