Geoneutrinos applications future directions and defining the Earths

Geoneutrinos: applications, future directions and defining the Earth’s engine Bill Mc. Donough, *Yu Huang +Ondřej Šrámek and Roberta Rudnick Geology, U Maryland Steve Dye, Natural Science, Hawaii Pacific U and Physics, U Hawaii Shijie Zhong, Physics, U Colorado Fabio Mantovani, Physics, U Ferrara, Italy *graduate +post-doc student

Update on Earth Models: …views from the last year! Murakami et al (May - 2012, Nature): “…the lower mantle is enriched in silicon … consistent with the [CI] chondritic Earth model. ” Campbell and O’Neill (March - 2012, Nature): “Evidence against a chondritic Earth” Zhang et al (March - 2012, Nature Geoscience): The Ti isotopic composition of the Earth and Moon overlaps that of enstatite chondrites. Fitoussi and Bourdon (March - 2012, Science): “Si isotopes support the conclusion that Earth was not built solely from enstatite chondrites. ” Warren (Nov - 2011, EPSL): “Among known chondrite groups, EH yields a relatively close fit to the stable-isotopic composition of Earth. ” - Compositional models differ widely, implying a factor of three difference in the U & Th content of the Earth

Nature & amount of Earth’s thermal power radiogenic heating vs secular cooling - abundance of heat producing elements (K, Th, U) in estimates of BSE from 9 TW to 36 TW the Earth - clues to planet formation processes constrains chondritic Earth models - amount of radiogenic power to drive mantle convection & plate tectonics estimates of mantle 1. 3 TW to 28 TW - is the mantle layered or does it have large deep superplume piles, e. g. , source of Hawaii structures? the future… Geoneutrino studies

Plate Tectonics, Convection, Geodynamo Radioactive decay driving the Earth’s engine!

1 s Earth’s surface heat flow 46 ± 3 (47 ± 2) Mantle cooling (18 TW) Crust R* (8 ± 1 TW) (Rudnick and Gao ‘ 03) Mantle R* (12 ± 4 TW) Core (~9 TW) - (4 -15 TW) total R* 20 ± 4 *R radiogenic heat (after Mc. Donough & Sun ’ 95) after Jaupart et al 2008 Treatise of Geophysics (0. 4 TW) Tidal dissipation Chemical differentiation

Arevalo, Mc. Donough, Luong (2009) EPSL Archean boundary Power (TW) Earth’s thermal evolution: role of K, Th & U

U in the Earth: Th/U = 4, K/U ~104 (established by chondrites) ~13 ng/g U in the Earth Metallic sphere (core) <<1 ng/g U Silicate sphere 20* ng/g U *O’Neill & Palme (2008) 10 ng/g *Turcotte & Schubert (2002) 31 ng/g Continental Crust 1300 ng/g U Mantle ~12 ng/g U Chromatographic separation Mantle melting & crust formation

2011 2005 Detecting Geoneutrinos from the Earth 2010

238 Terrestrial Antineutrinos U νe + p+ →n+ 232 e+ Th 1. 8 Me. V Energy Threshold 1α, 1β 234 Pa 1α, 1β 238 U νe 232 Th 2. 3 Me. V 40 K 31% νe 2. 1 Me. V 1% 5α, 2β 214 Bi 206 Pb Ac 4α, 2β νe νe 3. 3 Me. V 2. 3 Me. V 46% 2α, 3β 228 212 Bi 20% 40 K 1β 40 Ca Efforts to detect K geonus underway Terrestrial antineutrinos from uranium and thorium are detectable 1α, 1β 208 Pb

Determining Th/U is a challenge

Summary of geoneutrino results Constrainting U & Th in the Earth Mc. Donough, Learned, Dye (2012) Physics Today MODELS Cosmochemical: uses meteorites – O’Neill & Palme (’ 08); Javoy et al (‘ 10); Warren (‘ 11) Geochemical: uses terrestrial rocks – Mc. D & Sun ’ 95; Allegre et al ‘ 95; Palme O’Neil ‘ 03 Geophysical: parameterized convection – Schubert et al; Davies; Turcotte et al; Anderson

Earth’s geoneutrino flux X U or Th FX(r 0) Flux of anti-neutrinos from X at detector position r 0 AX Frequency of radioactive decay of X per unit mass NX Number of anti-neutrinos produced per decay of X R Earth radius a. X(r) Concentration of X at position r r(r) Density of earth at position r Interrogating the composition of the continental crust and “thermo-mechanical pile” (super-plumes? ) in the mantle …

Constructing a 3 -D reference model Earth assigning chemical and physical states to Earth voxels

Estimating the geoneutrino flux at SNO+ - Geology - Geophysics seismic x-section

Global to Regional RRM using only global inputs SNO+ Sudbury Canada improving our flux models adding the regional geology

Predicted Global geoneutrino flux based on our new Reference Model Yu Huang et al (2013) ar. Xiv: 1301. 0365

Models for understand Th & U in the Modern Mantle Inputs - Bulk Sil. Earth - Cont. Crust - Depleted Mantle Geonu data Data vs Models BSE Models

Structures in the mantle

Testing Earth Models Šrámek et al (2013) 10. 1016/j. epsl. 2012. 11. 001; ar. Xiv: 1207. 0853

Predicted Global geoneutrino flux - new Reference Model Yu Huang et al (2013) ar. Xiv: 1301. 0365 Predicted Mantle flux Šrámek et al (2013) 10. 1016/j. epsl. 2012. 11. 001; ar. Xiv: 1207. 0853

Present LS-detectors, data update? Borexino, Italy (0. 6 kt) SNO+, Canada (1 kt) Kam. LAND, Japan (1 kt) under construction (online later this yr? ) 9. 9 +4. 1 -3. 4 from May ‘ 07 to Dec ‘ 09 +29 106 -28 from 2002 to Nov 2009

LENA, EU (50 kt) Daya Bay II China (20 kt) Future detectors? Hanohano International ocean-based (50 kt)

DETECTOR DIMENSIONS inner detector - 50 kt of organic liquid scintillator (Ø 26 m) - 13, 500 photomultipliers outer muon veto 100 m - water Čerenkov detector - 2 m of active shielding m 30 LOCATION - mine or deep see plateau - depth of 4, 000 m. w. e. to reduce m-&cosmogenic background THE LENA DETECTOR AN OVERVIEW proton decay solar neutrinos terrestrial neutrinos atmospheric neutrinos artificial neutrino sources supernova neutrinos diffuse SN neutrino background PHYSICS GOALS

Daya Bay II Geoneutrino Signal

Hanohano An experiment with joint interests in Physics, Geology, and Security - multiple deployments - deep water cosmic shield - control-able L/E detection A Deep Ocean Deployment Sketch e Electron Anti-Neutrino Observatory Descent/ascent 39 min

Earth’s radiogenic (Th & U) power 20 ± 9 TW* (23 ± 10) Prediction: models range from 11 to 28 TW Future: -SNO+ online 2013 … 2020…? ? - Daya Bay II - LENA - Hanohano? - Neutrino Tomography …

Geoneutrinos: ongoing efforts and wish list - Directionality - 40 K geonus - Detecting hidden objects down there

Measuring Antineutrino Direction Reconstructed event direction Δθ Delayed n capture Δθ • Interaction kinematics • Neutron absorption • Position resolution • Scintillator properties θn Neutron Emission Angle νe Neutrino direction Prompt e+ Terrestrial antineutrino direction measurement shows promise • Much to gain for geology • Further study warranted after Hiroko Watanabe’s past presentations Neutron Kinetic Energy (ke. V)

Potassium Geo-neutrinos? • Absolute amount differs, but proportion of radiogenic heat production are similar • 40 K ~19%, 232 Th 42% and 238 U 39% • 40 K give the largest flux of geonus! • Where is the potassium in the Earth? • Continental crust has ~40%, mantle ~60% • K may reside in the Earth’s core after Mark Chen’s past presentations

Detecting 40 K-geoneutrinos Using 106 Cd based detectors (M. Chen, 2006) Directional Dark Matter detectors (Dye et al, 2013) elastic scattering on electrons

Plenty of suggestions for Geo-reactors deep inside the Earth Based on: R. de Meijer & W. van Westrenen South African Journal of Science (2008)