“ Georeactor ” Detection with Gigaton Antineutrino Detectors

1. “Georeactor” Detection with Gigaton Antineutrino Detectors Neutrinos and Arms Control Workshop February 5, 2004 Eugene Guillian University of Hawaii

2. Finding Hidden Nuclear Reactors • The focus of this conference is on detecting hidden man-made nuclear reactors • But there may be a natural nuclear reactor hidden in the Earth‘s core!

3. The “Georeactor” Model • An unorthodox model • Chief proponent: J.M.Herndon • The model • A fuel breeder fission reactor in the Earth‘s sub-core • Size: ~4 miles radius • Power: 3-10 TW

4. Man-made vs. Geo • Man-made: • (~500 reactors) x (~2 GW) = 1 TW • Georeactor: • 3-10 TW If a georeactor exists, it will be the dominant source of antineutrinos!

5. Outline of Presentation • Georeactor detection strategy • Describe the georeactor model • Can a georeactor be detected with KamLAND? • What minimum conditions are necessary to detect a georeactor?

6. Strategy for Georeactor Detection • If a georeactor does not exist…

8. From commercial power plants • Depends on the net power output • Rate corrected to 100% livetime & efficiency • Assume no neutrino oscillation

9. Corrected to 100% livetime & efficiency • Neutrino oscillation effect included

10. Slope = average neutrino oscillation survival probability

11. 2f = Spread <R> = Average

12. f = Spread Rmax = (1+f)<R> Rmin = (1-f)<R> <R> = Average

13. Y-inercept = Georeactor Rate 0

14. Strategy for Georeactor Detection • If a georeactor does exist…

15. 10 TW georeactor

16. Nonzero Y-intercept (0.0742 events/day @ 10 TW)

17. Georeactor Detection Strategy • Plot observed rate against expected background rate • Fit line through data • Y-intercept = georeactor rate

18. The Georeactor Model • What we can all agree on: • The Earth is made of the same stuff as meteorites • In its earliest stages, the Earth was molten • The Earth gradually cooled, leaving all but the outer core in solid form

19. Melting a Rock • Very high temperature: • All of rock in liquid form • Lower temperature: • Slag solidifies • Alloys and opaque minerals still in liquid form • Slag floats

20. Apply This Observation to the Earth Very Hot! All Liquid

21. Apply This Observation to the Earth Cooler Slag solidifies, Floats to surface

22. Fission Fuel Trapped by Slag? • Actinides (U, Th, etc.) are lithophile (or oxiphile) • If given a chance, they combine with slag • Slag rises to surface as the Earth cools • Fission fuel found in the Earth‘s crust and mantle, not in the core • Therefore, a georeactor cannot form!

23. Fission Fuel Trapped by Slag? • Actinides (U, Th, etc.) are lithophile (or oxiphile) • If given a chance, they combine with slag • Slag rises to surface as the Earth cools • Fission fuel found in the Earth‘s crust and mantle, not in the core • Therefore, a georeactor cannot form! If there is enough oxygen

24. If There Were Insufficient Oxygen • Some of the U, Th will be in alloy and sulfide form • These sink as the Earth cools • Elements with largest atomic number should sink most • Therefore, fission fuel should sink to the center of the Earth • Georeactor can form!

25. How Can One Tell if the Earth Is Oxygen Poor or Not? • Slag has high oxygen content • Alloys and opaque minerals have low oxygen content • Alloy/Slag mass ratio • Strong correlation with oxygen content in a meteorite

26. Oxygen Level of the Earth Enstatite Chrondite Less Slag Meteorite Data Alloy Slag More Slag Ordinary Chrondite Low Oxygen Content High

27. Oxygen Level of the Earth Less Slag Free actinides Alloy Slag Actinides trapped in slag More Slag Low Oxygen Content High

28. Oxygen Level of the Earth Less Slag Alloy Slag Core Mantle = Alloy Slag More Slag Low Oxygen Content High

29. Oxygen Level of the Earth Less Slag Core/Mantle ratio from seismic data Alloy Slag More Slag Low Oxygen Content High

30. Measuring the Earth‘s Oxidation Level • Equate the following: • Corealloy & opaque minerals • Mantle + Crustsilicates • Obtain Earth‘s mass ratio from density profile measured with seismic data • Compare with corresponding ratio in meteorites. • Oxygen Content of the Earth: • Same asmeteorite with same mass ratio as the Earth‘s

31. Evidence for Oxygen-poor Earth The Earth Seems to be Oxygen-poor! Herndon, J.M. (1996) Proc. Natl. Acad. Sci. USA 93, 646-648.

32. 3He Evidence for Georeactor • Fission reactors produce 3H • 3H decays to 3He (half life ~ 12 years)

33. 3He Measurements • In air: • RA = 3He/4He = 1.4 x 10-6 • From deep Earth: • R ≈ 8 x RA • Elevated deep Earth levels difficult to explain • Primordial 3He and “Just-so” dilution scenarios • A georeactor naturally produces 3He…

34. … and Just the Right Amount! SCALE Reactor Simulator (Oak Ridge) Deep Earth Measurement (mean and spread) Fig. 1, J.M.Herndon, Proc. Nat. Acad. Sci. USA, Mar. 18, 2003 (3047)

35. Other Phenomena • Georeactor as a fluctuating energy source for geomagnetism • 3 of the 4 gas giants radiate twice as much heat as they receive • Oklo natural fission reactor (remnant)

36. Can a Georeactor Be Detected with KamLAND? • KamLAND • A 0.4 kton antineutrino detector • Currently, the largest such detector in the world • 2-parameter fit • Slope (constrained) • Y-intercept (unconstrained)

37. Can a Georeactor Be Detected with KamLAND? • KamLAND • A 0.4 kton antineutrino detector • Currently, the largest such detector in the world • 2-parameter fit • Slope (constrained) • Y-intercept (unconstrained) Solar neutrino experiments

38. Can a Georeactor Be Detected with KamLAND? • KamLAND • A 0.4 kton antineutrino detector • Currently, the largest such detector in the world • 2-parameter fit • Slope (constrained) • Y-intercept (unconstrained) Georeactor Rate

39. Measuring the Georeactor Rate with KamLAND Slope constrained by solar neutrino measurements Georeactor rate Slope ≈ 0.75 ± 0.15

40. Large Background S/B ≈ 1/3 ~ 1/8 Background Signal

41. Slope Uncertainty Best fit 1s uncertainty in solar neutrino oscillation parameters (Dm2, sin22q) (rough estimate)

42. Can a Georeactor be Detected? • Use Error Ellipse to answer this question

43. Ellipse Equation

44. Ellipse Equation Distance of measured rate from true value Measured georeactor ne rate (y-intercept) True georeactor ne rate

45. Ellipse Equation Distance of measured slope from best estimate Best estimate of slope (from solar n experiments) Mueasured slope

46. Ellipse Equation Correlation between slope and rate measurements

47. Ellipse Equation Confidence level of fit result

48. Ellipse Equation Ellipse Parameters They determine the size of the ellipse

49. Ellipse Equation Ellipse Parameters Parameters depend on

50. Ellipse Parameters • <R> = average background rate • f = fractional spread of background rate • T = Exposure time • Rg = georeactor rate • sm = oscillation probability uncertainty • m0 = 0.75