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Georeactor Detection with Gigaton Antineutrino
Detectors

• Neutrinos and Arms Control Workshop
• February 5, 2004
• Eugene Guillian
• University of Hawaii

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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 Earths core!

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The Georeactor Model

• An unorthodox model
• Chief proponent J.M.Herndon
• The model
• A fuel breeder fission reactor in the Earths
  sub-core
• Size 4 miles radius
• Power 3-10 TW

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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!
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Outline of Presentation

1. Georeactor detection strategy
2. Describe the georeactor model
3. Can a georeactor be detected with KamLAND?
4. What minimum conditions are necessary to detect a
   georeactor?

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Strategy for Georeactor Detection

• If a georeactor does not exist

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(No Transcript)
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• From commercial power plants
• Depends on the net power output
• Rate corrected to 100 livetime efficiency
• Assume no neutrino oscillation

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• Corrected to 100 livetime efficiency
• Neutrino oscillation effect included

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Slope average neutrino oscillation
survival probability
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2f Spread
ltRgt Average
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f Spread
Rmax (1f)ltRgt
Rmin (1-f)ltRgt
ltRgt Average
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Y-inercept Georeactor Rate
0
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Strategy for Georeactor Detection

• If a georeactor does exist

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10 TW georeactor
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Nonzero Y-intercept (0.0742 events/day _at_ 10 TW)
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Georeactor Detection Strategy

• Plot observed rate against expected background
  rate
• Fit line through data
• Y-intercept georeactor rate

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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

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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

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Apply This Observation to the Earth
Very Hot!
All Liquid
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Apply This Observation to the Earth
Cooler
Slag solidifies, Floats to surface
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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 Earths crust and
  mantle, not in the core
• Therefore, a georeactor cannot form!

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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 Earths crust and
  mantle, not in the core
• Therefore, a georeactor cannot form!

If there is enough oxygen
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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!

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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

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Oxygen Level of the Earth
Enstatite Chrondite
Less Slag
Meteorite Data
Alloy Slag
More Slag
Ordinary Chrondite
Low
Oxygen Content
High
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Oxygen Level of the Earth
Less Slag
Free actinides
Alloy Slag
Actinides trapped in slag
More Slag
Low
Oxygen Content
High
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Oxygen Level of the Earth
Less Slag
Alloy Slag
Core Mantle

Alloy Slag
More Slag
Low
Oxygen Content
High
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Oxygen Level of the Earth
Less Slag
Core/Mantle ratio from seismic data
Alloy Slag
More Slag
Low
Oxygen Content
High
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Measuring the Earths Oxidation Level

• Equate the following
• Core ? alloy opaque minerals
• Mantle Crust ? silicates
• Obtain Earths mass ratio from density profile
  measured with seismic data
• Compare with corresponding ratio in meteorites.
• Oxygen Content of the Earth
• Same as meteorite with same mass ratio as the
  Earths

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Evidence for Oxygen-poor Earth
The Earth Seems to be Oxygen-poor!
Herndon, J.M. (1996) Proc. Natl. Acad. Sci. USA
93, 646-648.
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3He Evidence for Georeactor

• Fission reactors produce 3H
• 3H decays to 3He (half life 12 years)

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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

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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)
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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)

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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)

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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
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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
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Measuring the Georeactor Rate with KamLAND
Slope constrained by solar neutrino
measurements
Georeactor rate
Slope 0.75 0.15
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Large Background
S/B 1/3 1/8
Background
Signal
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Slope Uncertainty
Best fit
1s uncertainty in solar neutrino oscillation
parameters (Dm2, sin22q) (rough estimate)
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Can a Georeactor be Detected?

• Use Error Ellipse to answer this question

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Ellipse Equation
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Ellipse Equation
Distance of measured rate from true value
Measured georeactor ne rate (y-intercept)
True georeactor ne rate
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Ellipse Equation
Distance of measured slope from best estimate
Best estimate of slope (from solar n experiments)
Mueasured slope
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Ellipse Equation
Correlation between slope and rate measurements
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Ellipse Equation
Confidence level of fit result
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Ellipse Equation
Ellipse Parameters
They determine the size of the ellipse
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Ellipse Equation
Ellipse Parameters
Parameters depend on
Rg Georeactor rate
T Exposure time
ltRgt Average background rate
f Spread in background rate
sm Slope uncertainty
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Ellipse Parameters

• ltRgt average background rate
• f fractional spread of background rate
• T Exposure time
• Rg georeactor rate
• sm oscillation probability uncertainty
• m0 0.75

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Error Ellipse for KamLAND, 3 Years

• ltRgt 0.62 events/day
• f 16 (i.e. RMS(R)/ltRgt 0.16)
• T 3 years (12 down time fraction not
  included)
• Rg 0.0742 events/day (10 TW georeactor)
• sm 0.15 (slope uncertainty from solar n
  meas.)
• m0 0.75 (slope avg. surv. prob.)

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KamLAND, 3 Years
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KamLAND, How Many Years?
40 years for 90 confidence level!
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Effect of Background Spread
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Reducing the Background Level
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Slope Uncertainty Improvements
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Detector Size
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Gigaton Detector
1 Gigaton 2,500,000
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Gigaton Detector
Go 2.5 km along axis!
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Summary of Results

• Georeactor will NOT be observed with KamLAND
• Large spread in background rate helps
• Low background level
• ? Georeactor detectable with small detector

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Summary of Results

• Slope uncertainty
• Improved knowledge helps somewhat
• A 102 increase in detector size allows
  georeactor detection
• 1 Gigaton 2.5 million x KamLAND

Most antineutrinos detected by a gigaton
detector will be from the georeactor!
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Event Rate _at_ Gigaton Detector

• 0.0742 events/day
• 0.4 kton
• 10 TW

x 2,500,000
200,000 events/day
Expected rate from man-made reactors 20,000
ev/day
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Caveat

• In this analysis, information from the
  antineutrino energy spectrum was not used.
• Therefore the statement that KamLAND cannot say
  anything meaningful about a georeactor is
  premature
• Setting 90 limit may be possible
• Positive identification, however, is impossible

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Conclusion

• An array of gigaton detectors whose primary aim
  is arms control will definitely allow the
  detection of a georeactor (if it exists)
• The detection of a georeactor will have giant
  repercussions on our understanding of planet
  formation and geophysics

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Evidence for Oxygen-poor Earth (2)

• If we accept that the Earth was made from molten
  meteorites, the following mass ratios must hold

Mass(core) Mass(alloys, opaque minerals)
Mass(mantle)
Mass(slag)
Using density profile from seismic data
Meteorite data
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Evidence for Oxygen-poor Earth (3)
The Earth Seems to be Oxygen-poor!
Herndon, J.M. (1996) Proc. Natl. Acad. Sci. USA
93, 646-648.
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Earths Interior from Two Models
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3He/4He from the Georeactor Model
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)
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Detection Strategy
Background (commercial nuclear reactors)
Slope average oscillation survival
probability
Signal (georeactor)
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Detection Strategy
Slope constrained by solar neutrino
measurements
Georeactor rate
Slope 0.75 0.15
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Slope Uncertainty
Best fit
1s uncertainty in solar neutrino oscillation
parameters (Dm2, sin22q) (rough estimate)
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Slope Uncertainty
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Measuring the Georeactor Power

• Fit a line through data
• observed vs. expected rate

b georeactor rate m commercial reactor ne
avg. survival probability m0 best estimate
from solar n experiments sm estimated
uncertainty
xi expected ne rate yi observed ne rate si
stat. err. yi i bin index
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Measuring the Georeactor Power

• Fit a line through data
• observed vs. expected rate

Measure this
b georeactor rate m commercial reactor ne
avg. survival probability m0 best estimate
from solar n experiments sm estimated
uncertainty
xi expected ne rate yi observed ne rate si
stat. err. yi i bin index
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Line Fit to Data
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What Conditions are Necessary to Detect a 10 TW
Georeactor?

• Detector size
• Signal and background scale by the same factor
• Exposure time
• Overall increase in statistics
• Slope (average survival probability)
• Uncertainty that is independent of exposure time
• Improvement over time with more/better solar n
  measurements
• Commercial reactor background
• Spread in background level

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Error Contour Formula
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Error Contour Formula

• ltRgt average background rate
• f fractional spread of background rate
• T Exposure time
• Rg georeactor rate
• sm oscillation probability uncertainty
• m0 0.75

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KamLAND, 3 Years
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KamLAND, How Many Years?
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Summary of Results

• Improved knowledge of neutrino oscillation
  parameters help, but not enough to allow KamLAND
  to detect a georeactor
• A x100 increase in detector size will allow 99
  detection of a 10TW georeactor, even under high
  background conditions as in KamLAND
• Dont need to go all the way to a gigaton
  (x2000), although it will allow a comfortable
  margin