Geo-neutrinos: combined KamLAND and Borexino analysis, and future
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Transcript of Geo-neutrinos: combined KamLAND and Borexino analysis, and future
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Geo-neutrinos: combined KamLAND and Borexino analysis, and future
1° Neutrino Geoscience
Honolulu 14-16 December 2005
Fabio Mantovani – University of Ferrara & INFNFabio Mantovani – University of Ferrara & INFN
4° Neutrino Geoscience Takayama 21-23 March 2013
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Summary• An historical perspective
• How to look into the deep Earth?
• Why the refined local and global models are important?
• New Borexino and KamLAND results: theory vs experiments
• Multi-site “view” of the mantle
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Geo-neutrinos: anti-neutrinos from the EarthGeo-neutrinos: anti-neutrinos from the Earth
U, Th and 40K in the Earth release heat together with anti-neutrinos,
in a well fixed ratio:
• Earth emits (mainly) antineutrinos whereas Sun shines in neutrinos.
• A fraction of geo-neutrinos from U and Th (not from 40K) are above threshold for inverse on protons:
• Different components can be distinguished due to different energy spectra: e. g. anti- with highest energy are from Uranium.
• Signal unit: 1 TNU = one event per 1032 free protons per year
p e n 1.8 MeV
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Geo-neutrinos born on board of the Santa Fe Chief trainGeo-neutrinos born on board of the Santa Fe Chief train
In 1953 G. Gamow wrote to F. Reines: “It just occurred to me that your background may just be coming from
high energy beta-decaying members of U and Th families in the crust of the Earth.”
F. Reines answered to G. Gamow: “Heat loss from Earth’s surface is 50 erg cm−2 s−1.
If assume all due to beta decay than have only enough energy for about 108 one-MeV neutrinos cm−2 and s.”
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Geoneutrino signal: an historical perspectiveGeoneutrino signal: an historical perspective
Models assuming uniform U distribution in the Earth:
• Eder (Nucl. Phys. 1966)
• Marx (Cz. J. Phys 1969)
• Kobayashi (GRL 1991)
Model with an uniform distribution of U in the continental crust:
• Krauss et al. (Nature 1984)
2° x 2° crustal model with BSE constraint (papers after 2004)
BSE model with different U distribution between crust and mantle:
• Rothschild et al. (1991)
▲ Raghavan et al. (1998) KamLAND and Borexino measurements
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How to look into the deep Earth?How to look into the deep Earth?Expected signal in SNO+ (2013-14)
• 82 % from crust
• 18 % from mantle
Expected signal in KamLAND (2002)
• 75 % from crust
• 25 % from mantle
Expected signal in Borexino (2007)
• 75 % from crust
• 25 % from mantleReconstruction of
geo- direction
with Gd, Li and B
loaded LS is being
investigated by
several groups.
(See Shimizu,
Domogatsky et al.,
Hochmuth et al.)
Expected signal in Hawaii
• 28 % from crust
• 72 % from mantleSee Jocher et al. 2013
John Learned talk – Saturday 23 March – 10.00 @ NGS13
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?
arXiv:1204.1923v1 [hep-ph] Apr 2012
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Modeling geo-neutrino signalModeling geo-neutrino signal
For each element (U, Th) the expected geo-neutrino signal S in one site on the Earth’s surface is the sum of three contributions:
RExpected al e O Cst f rust MantlL C eOS S S S
LOC (~500 x 500 km)
• Refined geophysical model of the crust• Main tectonic structures• Direct and detailed survey of U and Th content • Hierarchy of uncertainties sources
ROC
• Discrimination of OC and CC• Thickness and extension of the main continental reservoirs• U and Th abundance of the crustal layers• Evaluation of the uncertainties
Measured LO al est f rustM Rantle C O CS S (S S )
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A refined local model for KamiokaA refined local model for Kamioka
A world wide reference model* predicts for KamLAND:
* Mantovani et al. – Phys. Rev. D 69 – 2004 - hep-ph/0309013
Total signal 32.4 ± 8.3 TNU
Local signal (6 tiles) 16.5 TNU
Inputs used for the refinement
• Use a geochemical study of the
Japan Arc exposed upper crust
(166 samples distinguishing 10
geological classes)
• Use detailed (± 1 km)
measurements of Conrad and
Moho depth
• Use selected values for
abundances LC
• Build a new crustal map of the
Japan Arc (scale ¼° x ¼°)
• Consider possible effect of the
subducting plate
below Japan
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Local contribution to geo- signal in KamLANDLocal contribution to geo- signal in KamLAND
Different local sources of geo- are investigated
and the expected signals are estimated:
Reservoir S(Th) [TNU] S(U) [TNU]
Six-tiles 3.20 ± 0.37 11.17 ± 0.65
Subducting slub 0.90 ± 0.27 2.02 ± 0.61
Sea of Japan 0.09 ± 0.03 0.34 ± 0.10
LOC Total 4.19 ± 0.46 13.53 ± 0.90
• The local expected signal is 17.7 ± 1.4 TNU to
compare with 16.4 TNU
• For a fixed element the 1 uncertainties are
independent
• We assume S(U) and S(Th) totally correlated
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Local contribution to geo- signal in BorexinoLocal contribution to geo- signal in Borexino
A world wide reference model predicts for Borexino:
Total signal 39.1 ± 8.0 TNU
Signal from 6 tiles 15.0 TNU
Signal from CT 11.8 TNU
Inputs used for the refinement
• The geophysical structure of the
crust is modeled using data of
CROP seismic sections and from
38 deep oil and gas wells.
• We identify 6 reservoirs: 4 of
sediments, UC and LC.
• Representative samples of the
sedimentary cover were collected
and measured by using ICP-MS
• U and Th content
measured in samples
collected from outcrops
on Alps is adopted
for UC and LC
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The main results of this study
are about the thickness of
layers and their composition.
Before the refinement After refinement
Res. z [km] a(Th) [mg/g] a(U) [mg/g] z [km] a(Th) [mg/g] a(U) [mg/g]
Sed. ~ 0.5 6.9 1.67 ~ 13 2.00 ± 0.17 0.80 ± 0.07
UC ~ 10 9.8 2.5 ~ 13 8.1 ± 1.6 2.20 ± 0.43
MC ~ 10 6.1 1.6 / / /
LC ~ 10.5 3.7 0.6 ~ 8 2.6 ± 1.2 0.30 ± 0.10
A refined local model for BorexinoA refined local model for Borexino
The local expected signal calculated signal is SAfter = 9.7 ± 1.3 TNU to
compare with SBefore = 15.0 TNU.
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The Rest Of the CrustThe Rest Of the Crust
Main inputs for calculating geo- signal from the crust: The CRUST2.0 crustal model (Laske G. et al. 2001). For each of the 16200 tiles density and thickness of sediments, upper, middle and lower crust are given. Values of the U and Th mass abundance in each layer taken by review papers (Plank & Langmuir 98, Rudnick & Gao 03).
Why do we need a refinement of the crustal
model?
• We need to evaluate the uncertainties of the geophysical crustal model• New compilations of U and Th abundances are published• An updated 1°x1° map of the sediments is available• New approach based on seismic arguments can be used in the evaluation of U and Th abundances (and their uncertainties) in MC and LCYu Huang talk
Friday 22 March – 14.00 @ NGS13
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Theory vs experimentsTheory vs experiments
1 Fiorentini et al. 2012; 2 Huang et al. 2013
RExpected al e O Cst f rust MantlL C eOS S S S
Expected geoneutrino signal [TNU]
Crust MantleTotal
LOC1 ROC2 CLM2 Mantle2
KamLAND 17.7 ± 1.4 7.3 ± 1.4 1.6 ± 1.6 8.8 35.4 ± 2.5
Borexino 9.7 ± 1.3 13.7 ± 2.5 2.2 ± 2.2 8.7 34.3 ± 3.6
Measured geoneutrino signal [TNU]
KamLAND 2013 31.1 ± 7.3
Borexino 2013 38.8 ± 12.0
These expected signals can be
compared with the data published
in 2013 by KamLAND and
Borexino collaborations.
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0
10
20
30
40
50
60
70
80
90
100
2002 2004 2006 2008 2010 2012 2014
Year
Sig
nal [
TN
U]
Measured geoneutrino signals in the last yearsMeasured geoneutrino signals in the last years
KamLAND
Data taking from March 02
Year Geo-nu S [TNU]
2005 63 +28 -25
2007 39.4 +14.4 -14.3
2010 38.3 +10.3 -9.9
2013 31.1+7.3-7.3
0
10
20
30
40
50
60
70
80
90
100
2007 2009 2011 2013
Year
Sig
nal [
TN
U]
Borexino
Data taking from Dec. 07
Year Geo-nu S [TNU]
2010 64.8 +26.6 -21.6
2013 38.8 +12 -12
Expected signal*
Expected signal*
*Fiorentini et al. 2012 arXiv:1204.1923v2 + Huang et al. 2013
Two independent experiments, far ~104 km each other, measure a geo- signal in good agreement with the expectation.
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Multi-site “view” of the mantleMulti-site “view” of the mantle
CruMe stasure led MantS SS
al est f rusR tLO CC usC O r tS S S LOC [TNU]1 ROC [TNU]2 Crust total [TNU]
KamLAND 17.7 ± 1.4 7.3 ± 1.4 25.0 ± 2.0
Borexino 9.7 ± 1.3 13.7 ± 2.5 23.4 ± 2.8
2013 data [TNU] Crust [TNU] Mantle [TNU]
KamLAND 31.1 ± 7.3 25.0 ± 2.0 6.1 ± 7.6
Borexino 38.8 ± 12.0 23.4 ± 2.8 15.4 ± 12.3
1 Fiorentini et al. 2012; 2 Huang et al. 2013
Preliminary
Preliminary
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Geo-, global U mass and radiogenic heat powerGeo-, global U mass and radiogenic heat power• For a fixed site on Earth’s surface the expected geo- signal from U depends on its global mass m(U) and its distribution inside the Earth:
Manlte Crustm U m U m U
• For a fixed m(U) , the highest and lowest signal is obtained with these U distributions:
• maximal amount of U tolerated by crustal models• the remaining U mass homogeneously distributed in the mantle
• minimal amount of U tolerated by crustal models• the remaining U mass displaced on the bottom of the mantle
m(U)
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Geological implications of new KL and BX results
Geological implications of new KL and BX results
Region allowed by a BSE
model with a global m(U) = 0.8
± 0.1 1017 kg and Th/U = 3.9.
The graph is site dependent:
the “slope” is universal
the intercept depends on the site (crust effect)
the width depends on the site (crust effect)
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Implications of KL and BX on terrestrial radiogenic heatImplications of KL and BX on terrestrial radiogenic heat
• New results based on ~40.000 measurements in deep bore-holes (55% more than used in previous estimates)
• Heat loss through the sea floor is estimated by half space model.
mW / m2Global heat loss [TW]
Williams and von Herzen [1974]
43
Davies [1980] 41
Sclater et al. [1980] 42
Pollack et al. [1993] 44 ± 1
Hofmeister et al. [2005] 31 ± 1
Jaupart et al. [2007] * 46 ± 3
Davies and Davies [2010] 47 ± 2
For the first time the global terrestrial
heat power from U and Th is
measured in two different locations
H(U+Th) [TW]
KamLAND 13 ± 9
Borexino 23 ± 14
Preliminary
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Waiting SNO+…
1° Neutrino Geoscience
Honolulu 14-16 December 2005
4° Neutrino Geoscience Takayama 21-23 March 2013
See you for Neutrino Geoscience in 2020!
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