Present and future of Geoneutrinos Bill Mc Donough
Present and future of Geo-neutrinos Bill Mc. Donough 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 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 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 1 o x “z” tile mapping of elements Huang et al (2013) G-cubed ar. Xiv: 1301. 0365
Uranium Abundance in Middle Continental Crust layer UMCC (mg/g) Average middle Cont. Crust U abundance is 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 ar. Xiv: 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 (238 U & 232 Th) Šrámek et al (2013) EPSL 10. 1016/j. epsl. 2012. 11. 001; ar. Xiv: 1207. 0853
Slope = 1. 0 The Mantle beneath the global array of detectors sees a uniform mantle flux (~10% variation) Intercept = ~8 TNU present uncertainty is large (± 6 TNU), comparable to other recent reports
Predicted geoneutrino flux Total flux at surface dominated by Continental crust Yu Huang et al (2013) G-cubed ar. Xiv: 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; ar. Xiv: 1207. 0853
Hanohano An experiment with joint interests in Physics, Geology, and Security Size: scalable from 1 to 50 k. T 10 -yr cost est: $250 M @ 10 k. T - 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 – 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 20 m x 35 m fiducial vol. 1 m oil 2 m pure water • Power and comm, no problems • Optical detector, prototypes OK • Need second round design 16 June 2008 John Learned at LBL 15
Ocean Deployments Sketch of prototype detector ~ 1 m for deployment off Honolulu by Kilo Moana: U Hawaii operated UNOLS vessel, based at HNL UNOLS: University-National Oceanographic Laboratory System
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