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

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

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

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.”

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

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

?

arXiv:1204.1923v1 [hep-ph] Apr 2012

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 )

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

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

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

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.

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

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.

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.

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

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)

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)

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

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!