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Present and future of Geo-neutrinos Bill McDonough Geology, U Maryland Plate Tectonics, Convection, Geodynamo Does heat from radioactive decay drive the Earth’s engine? 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 9TW to 36TW the Earth - clues to planet formation processes constrains chondritic Earth models - amount of radiogenic power to drive mantle convection & plate tectonics estimates of mantle 1.3TW to 28TW - is the mantle compositionally layered? or has large layers, LLSVP, superplume piles structures? the future is… Geoneutrino studies Summary of geoneutrino results SILICATE EARTH MODELS TW scales relative to U Cosmochemical: uses meteorites – 10 TW 10, 20, 30 TW ≈ 10, 20, 30 ppb Geochemical: uses terrestrial rocks –20 TW Geodynamical: parameterized convection – 30 TW Constructing a 3-D reference model Earth assigning chemical and physical states to Earth voxels 1o x 1o x “z” tile mapping of elements Huang et al (2013) G-cubed arXiv:1301.0365 Uranium Abundance in Middle Continental Crust layer UMCC (mg/g) Average middle Cont. Crust U abundance is 0.97 0.58 0.36 mg/g Rudnick and Gao (2003) 1.3 mg/g Predicted Global geoneutrino flux based on our new Reference Model Geoneutrino detection rate Huang et al (2013) G-cubed arXiv:1301.0365 10.1002/ggge.20129 --TNU: Terrestrial Neutrino Unit -- 1 TNU = one geoneutrino event per 1032 free protons per year Near Field: six closest 2° × 2° crustal voxels Far Field = bulk crust – near field crust What’s hidden in the mantle? Seismically slow “red” regions in the deep mantle Can we image it with geonus? Ritsema et al (Science, 1999) Testing Earth Models Mantle geoneutrino flux (238U & 232Th) Šrámek et al (2013) EPSL 10.1016/j.epsl.2012.11.001; arXiv:1207.0853 50 40 30 Total flux (TNU) 20 Intercept = ~8 TNU present uncertainty is large (±6 TNU), comparable to other recent reports SNO+ Borexino KamLAND m= 1.0 Slope = 1.0 The Mantle beneath the global array of detectors sees a uniform mantle flux (~10% variation) Oceanic detector 10 b = 8.4 (TNU) Mantle contribution 0 0 10 20 30 40 Crustal contribution to flux (TNU) Predicted geoneutrino flux Total flux at surface dominated by Continental crust Yu Huang et al (2013) G-cubed arXiv:1301.0365 10.1002/ggge.20129 Mantle flux at the Earth’s surface dominated by deep mantle structures Šrámek et al (2013) EPSL 10.1016/j.epsl.2012.11.001; arXiv:1207.0853 Hanohano An experiment with joint interests in Physics, Geology, and Security Size: scalable from 1 to 50 kT 10-yr cost est: $250M @ 10 kT - 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 2 Candidate Off-shore Sites for Physics San Onofre, California- ~6 GWth Maanshan, Taiwan- ~5 GWth Need study of backgrounds versus depth 16 June 2008 John Learned at LBL 14 Addressing Technology Issues • Scintillating oil studies in lab 20m x 35m fiducial vol. – P=450 atm, T=0°C – Testing PC, PXE, LAB and dodecane – No problems so far, LAB favorite… optimization needed 1 m oil • Implosion studies 2m pure water – 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 1 0.8 Pressure (norm) 0.6 0.4 0.2 0 0.0025 -0.2 0.0035 0.0045 0.0055 0.0065 0.0075 0.0085 0.0095 -0.4 -0.6 30% Foam filled (4105m) Empty (4280m) -0.8 -1 Time (seconds) 16 June 2008 John Learned at LBL 15 Ocean Deployments Sketch of prototype detector ~ 1m for deployment off Honolulu by Kilo Moana Kilo Moana: U Hawaii operated UNOLS vessel, based at HNL UNOLS: University-National Oceanographic Laboratory System