Review Article Studying the Earth with Geoneutrinosdownloads.hindawi.com/journals/ahep/2013/425693.pdf · Advances in High Energy Physics IntheEarth,thegeoneutrinosourcesarespreadovera

Hindawi Publishing CorporationAdvances in High Energy PhysicsVolume 2013 Article ID 425693 16 pageshttpdxdoiorg1011552013425693

Review ArticleStudying the Earth with Geoneutrinos

L Ludhova1 and S Zavatarelli2

1 Dipartimento di Fisica INFN 20133 Milano Italy2 Dipartimento di Fisica INFN 16146 Genova Italy

Correspondence should be addressed to L Ludhova livialudhovamiinfnit

Received 14 July 2013 Accepted 18 September 2013

Academic Editor Elisa Bernardini

Copyright copy 2013 L Ludhova and S ZavatarelliThis is an open access article distributed under the Creative CommonsAttributionLicense which permits unrestricted use distribution and reproduction in anymedium provided the originalwork is properly cited

Geoneutrinos electron antineutrinos from natural radioactive decays inside the Earth bring to the surface unique informationabout our planetThe new techniques in neutrino detection opened a door into a completely new interdisciplinary field of neutrinogeoscience We give here a broad geological introduction highlighting the points where the geoneutrino measurements can givesubstantial new insights The status-of-art of this field is overviewed including a description of the latest experimental resultsfrom KamLAND and Borexino experiments and their first geological implications We performed a new combined Borexino andKamLAND analysis in terms of the extraction of themantle geo-neutrino signal and the limits on the Earthrsquos radiogenic heat powerThe perspectives and the future projects having geo-neutrinos among their scientific goals are also discussed

1 Introduction

The newly born interdisciplinar field of neutrino geosciencetakes the advantage of the technologies developed by large-volume neutrino experiments and of the achievements ofthe elementary particle physics in order to study the Earthinterior with new probe geoneutrinos Geoneutrinos areelectron antineutrinos released in the decays of radioactiveelements with lifetimes comparable with the age of the Earthand distributed through the Earthrsquos interior The radiogenicheat released during the decays of these Heat ProducingElements (HPE) is in a well fixed ratio with the total massof HPE inside the Earth Geoneutrinos bring to the Earthrsquossurface an instant information about the distribution of HPEThus it is in principle possible to extract from measuredgeoneutrino fluxes several geological information completelyunreachable by other means This information concerns thetotal abundance and distribution of the HPE inside the Earthand thus the determination of the fraction of radiogenic heatcontribute to the total surface heat flux Such a knowledge isof critical importance for understanding complex processessuch as the mantle convection the plate tectonics and thegeodynamo (the process of generation of the Earthrsquosmagneticfield) as well as the Earth formation itself

Currently only two large-volume liquid-scintillator neu-trino experiments KamLAND in Japan and Borexino in Italy

have been able tomeasure the geoneutrino signal Antineutri-nos can interact only through theweak interactionsThus thecross-section of the inverse-beta decay detection interaction

]119890+ 119901 997888rarr 119890

+

+ 119899 (1)

is very low Even a typical flux of the order of 106 geoneutrinoscmminus2 sminus1 leads to only a hand-full number of interactionsfew or few tens per year with the current-size detectors Thismeans that the geoneutrino experiments must be installed inunderground laboratories in order to shield the detector fromcosmic radiations

The aimof the present paper is to review the current statusof the neutrino geoscience First in Section 2 we describe theradioactive decays of HPE and the geoneutrino productionthe geoneutrino energy spectra and the impact of the neu-trino oscillation phenomenon on the geoneutrino spectrumand flux Section 3 is intended to give an overview of the cur-rent knowledge of the Earth interiorThe opened problems towhich understanding the geoneutrino studies can contributeto are highlighted Section 4 sheds light on how the expectedgeoneutrino signal can be calculated considering differentgeological models Section 5 describes the KamLAND andthe Borexino detectors Section 6 describes details of thegeoneutrino analysis from the detection principles throughthe background sources to the most recent experimental

2 Advances in High Energy Physics

results and their geological implications Finally in Section 7we describe the future perspectives of the field of neutrinogeoscience and the projects having geoneutrino measure-ment among their scientific goals

2 Geoneutrinos

Today the Earthrsquos radiogenic heat is in almost 99 producedalong with the radioactive decays in the chains of 232Th(12059112

= 140 sdot 109 year) 238U (120591

12= 447 sdot 10

9 year)235U (120591

12= 070 sdot 10

9 year) and those of the 40K isotope(12059112

= 128 sdot 109 year) The overall decay schemes and the

heat released in each of these decays are summarized in thefollowing equations

238U 997888rarr206Pb+8120572 + 8119890minus + 6]

119890+ 517MeV (2)

235U 997888rarr207Pb+7120572 + 4119890minus + 4]

119890+ 464MeV (3)

232Th 997888rarr208Pb+6120572 + 4119890minus + 4]

119890+ 427MeV (4)

40K 997888rarr40Ca+119890minus + ]

119890+ 131MeV (893) (5)

40K+119890 997888rarr40Ar+]

119890+ 1505MeV (107) (6)

Since the isotopic abundance of 235U is small the overallcontribution of 238U 232Thand 40K is largely predominantIn addition a small fraction (less than 1) of the radiogenicheat is coming from the decays of 87Rb (120591

12= 481sdot10

9 year)138La (120591

12= 102sdot10

9 year) and 176Lu (12059112

= 376sdot109 year)

Neutron-rich nuclides like 238U 232Th and 235U madeup [1] by neutron capture reactions during the last stagesof massive-stars lives decay into the lighter and proton-richer nuclides by yielding 120573minus and 120572 particles see (2)ndash(4)During 120573

minus decays electron antineutrinos (]119890) are emitted

that carry away in the case of 238U and 232Th chains 8and 6 respectively of the total available energy [2] In thecomputation of the overall ]

119890energy spectrum of each decay

chain the shapes and rates of all the individual decays haveto be included detailed calculations are required to take intoaccount up to sim80 different branches for each chain [3] Themost important contributions to the geoneutrino signal arehowever those of 214Bi and 234Pa119898 in the uranium chainand 212Bi and 228Ac in the thorium chain [2]

Geoneutrino spectrum extends up to 326MeV and thecontributions originating from different elements can bedistinguished according to their different end-points thatis geoneutrinos with E gt225MeV are produced only theuranium chain as shown in Figure 1 We note that accordingto geochemical studies 232Th is more abundant than 238Uand their mass ratio in the bulk Earth is expected to be119898(232Th)119898(

238U) = 39 (see also Section 3) Because thecross-section of the detection interaction from (1) increaseswith energy the ratio of the signals expected in the detectoris 119878(232Th)119878(

238U) = 027The 40K nuclides presently contained in the Earth were

formed during an earlier and more quiet phase of themassive-stars evolution the so-called Silicon burning phase

1018

1016

1014

1012

Lum

inos

ity (s

minus1

MeV

minus1)

05 1 15 2 25 3 35 4Antineutrino energy (MeV)

238U series235U series

232Th series40K

Figure 1 The geoneutrino luminosity as a function of energy isshown for themost important reaction chains and nuclides [4] Onlygeoneutrinos of energies above the 18MeV energy (vertical dashedline) can be detected by means of the inverse beta decay on targetprotons shown in (1)

[1] In this phase at temperatures higher than 35 sdot 109 K

120572 particles protons and neutrons were ejected by photo-disintegration from the nuclei abundant in these stars andwere made available for building-up the light nuclei up toand slightly beyond the iron peak (119860 = 65) Being a lighternucleus the 40K beyond the 120573minus decay shown in (5) has alsoa sizeable decay branch (107) by electron capture see (6) Inthis case electronneutrinos are emitted but they are not easilyobservable because they are overwhelmed by themany ordersof magnitude more intense solar-neutrino fluxes Luckily theEarth is mostly shining in antineutrinos the sun converselyis producing energy by light-nuclide fusion reactions andonly neutrinos are yielded during such processes

Both the 40K and 235U geoneutrinos are below the18MeV threshold of (1) as shown in Figure 1 and thus theycannot be detected by this process However the elementalabundances ratios are much better known than the absoluteabundances Therefore by measuring the absolute content of238U and 232Th also the overall amount of 40K and 235Ucan be inferred with an improved precision

Geoneutrinos are emitted and interact as flavor statesbut they do travel as superposition of mass states and aretherefore subject to flavor oscillations

In the approximation Δ119898231sim Δ119898

2

32≫ Δ119898

2

21 the square-

mass differences of mass eigenstates 1 2 and 3 the survivalprobability 119875

119890119890for a ]

119890in vacuum is

119875119890119890= 119875 (]

119890997888rarr ]119890)

= sin412057913+ cos4120579

13(1 minus sin22120579

12sin2 (

1267Δ1198982

21119871

4119864

))

(7)

Advances in High Energy Physics 3

In the Earth the geoneutrino sources are spread over avast region compared to the oscillation length

119871119900sim 120587119888ℎ

4119864

Δ1198982

21

(8)

For example for asim3MeVantineutrino the oscillation lengthis of sim100 km small with respect to the Earthrsquos radius ofsim6371 km and the effect of the neutrino oscillation to thetotal neutrino flux is well averaged giving an overall survivalprobability of

⟨119875119890119890⟩ ≃ cos4120579

13(1 minus

1

2

sin2212057912) + sin4120579

13 (9)

According to the neutrino oscillation mixing angles andsquare-mass differences reported in [5] 119875

119890119890sim 054

While geoneutrinos propagate through the Earth theyfeel the potential of electrons and nucleons building-up thesurrounding matter The charged weak current interactionsaffect only the electron flavor (anti)neutrinos As a con-sequence the Hamiltonian for ]

119890rsquos has an extra term of

radic2119866119865119899119890 where 119899

119890is the electron density Since the electron

density in the Earth is not constant and moreover it showssharp changes in correspondencewith boundaries of differentEarthrsquos layers the behavior of the survival probability isnot trivial and the motion equations have to be solved bynumerical tracing It has been calculated in [3] that thisso-called matter effect contribution to the average survivalprobability is an increase of about 2 and the spectraldistortion is below 1

To conclude the net effect of flavor oscillations duringthe geoneutrino (]

119890) propagation through the Earth is the

absolute decrease of the overall flux bysim055with a very smallspectral distortion negligible for the precision of the currentgeoneutrino experiments

3 The Earth

The Earth was created in the process of accretion fromundifferentiated material to which chondritic meteorites arebelieved to be the closest in composition and structure TheCa-Al rich inclusions in carbonaceous chondrite meteoritesup to about a cm in size are the oldest known solid conden-sates from the hotmaterial of the protoplanetary diskThe ageof these fine grained structures was determined based on U-corrected Pb-Pb dating to be 456730 plusmn 016 million years [6]Thus these inclusions together with the so-called chondrulesanother type of inclusions of similar age provide an upperlimit on the age of the Earth The oldest terrestrial material iszircon inclusions fromWesternAustralia being at least 4404-billion-year old [7]

The bodies with a sufficient mass undergo the processof differentiation for example a transformation from anhomogeneous object to a body with a layered structure Themetallic core of the Earth (and presumably also of otherterrestrial planets) was the first to differentiate during the firstsim30 million years of the life of the Solar System as inferredbased on the 182Hf - 182W isotope system [8] Today the core

has a radius of 2890 km about 45 of the Earth radius andrepresents less than 10 of the total Earth volume

Due to the high pressure of about 330GPa the Inner Corewith 1220 km radius is solid despite the high temperatureof sim5700K comparable to the temperature of the solarphotosphere

From seismologic studies and namely from the factthat the secondary transverseshear waves do not propagatethrough the so-called Outer Core we know that it is liquidTurbulent convection occurs in this liquid metal of lowviscosity These movements have a crucial role in the processof the generation of the Earth magnetic field so-calledgeodynamoThemagnetic field here is about 25Gauss about50 times stronger than at the Earthrsquos surface

The chemical composition of the core is inferred indi-rectly as Fe-Ni alloy with up to 10 admixture of lightelements most probable being oxygen andor sulfur Somehigh-pressure high-temperature experiments confirm thatpotassium enters iron sulfidemelts in a strongly temperature-dependent fashion and that 40Kcould thus serve as a substan-tial heat source in the core [9] However other authors showthat several geochemical arguments are not in favor of suchhypothesis [10] Geoneutrinos from 40K have energies belowthe detection threshold of the current detection method (seeFigure 1) and thus the presence of potassium in the corecannot be tested with geoneutrino studies based on inversebeta on free protons Other heat producing elements suchas uranium and thorium are lithophile elements and due totheir chemical affinity they are quite widely believed not tobe present in the core (in spite of their high density) Thereexist however ideas as that of Herndon [11] suggesting anU-driven georeactor with thermal power lt30 TW present inthe Earthrsquos core and confined in its central part within theradius of about 4 kmTheantineutrinos thatwould be emittedfrom such a hypothetical georeactor have as antineutrinosfrom the nuclear power plants energies above the end-pointof geoneutrinos from ldquostandardrdquo natural radioactive decaysAntineutrino detection provides thus a sensitive tool to testthe georeactor hypothesis

After the separation of the metallic core the rest of theEarthrsquos volumewas composed by a presumably homogeneousPrimitive Mantle built of silicate rocks which subsequentlydifferentiated to the present mantle and crust

Above the Core Mantle Boundary (CMB) there is asim200 km thick zone called D10158401015840 (pronounced D-doubleprime) a seismic discontinuity characterized by a decreasein the gradient of both 119875 (primary) and 119878 (secondary shear)wave velocities The origin and character of this narrow zoneis under discussion and there is no widely accepted model

The Lower Mantle is about 2000 km thick and extendsfrom the D10158401015840 zone up to the seismic discontinuity at thedepth of 660 km This discontinuity does not representa chemical boundary while a zone of a phase transi-tion and mineral recrystallization Below this zone in theLower Mantle the dominant mineral phases are the Mg-perovskite (Mg

09Fe01)SiO3 ferropericlase (Mg Fe)O and

Ca-perovskite CaSiO3 The temperature at the base of the

mantle can reach 3700K while at the upper boundary


the temperature is about 600K In spite of such hightemperatures the high lithostatic pressure (136GPa at thebase) prevents the melting since the solidus increases withpressure The Lower Mantle is thus solid but viscose andundergoes plastic deformation on long time-scales Due toa high temperature gradient and the ability of the mantleto creep there is an ongoing convection in the mantleThis convection drives the movement of tectonic plates withcharacteristic velocities of few cm per year The convectionmay be influenced by themineral recrystallizations occurringat 660 km and 410 km depths through the density changesand latent heat

The mantle between these two seismic discontinuities at410 and 660 km depths is called the Transition Zone Thiszone consists primarily of peridotite rock with dominantminerals garnet (mostly pyrop Mg

3Al2(SiO4)3) and high-

pressure polymorphs of olivine (Mg Fe)2SiO4 ringwoodite

and wadsleyite below and above cca 525 km depth respec-tively

In the Upper Mantle above the 410 km depth disconti-nuity the dominant minerals are olivine garnet and pyrox-ene The upper mantle boundary is defined with seismicdiscontinuity called Mohorovicic often referred to as MohoIt is average depth is about 35 km 5ndash10 km below the oceansand 20ndash90 km below the continents The Moho lies withinthe lithosphere the mechanically defined uppermost Earthlayer with brittle deformations composed of the crust andthe brittle part of the upper mantle Continental LithosphericMantle (CLM) The lithospheric tectonic plates are floatingon the more plastic asthenosphere entirely composed of themantle material

Partial melting is a process when solidus and liquidustemperatures are different and are typical for heterogeneoussystems as rocks The mantle partial melting through geo-logical times leads to the formation of the Earthrsquos crustTypical mantle rocks have a higher magnesium-to-iron ratioand a smaller proportion of silicon and aluminum than thecrust The crust can be seen as the accumulation of solidifiedpartial liquid which thanks to its lower density tends tomove upwards with respect to denser solid residual Thelithophile and incompatible elements such as U and Thtend to concentrate in the liquid phase and thus they doconcentrate in the crust

There are two types of the Earthrsquos crust The simplestand youngest is the oceanic crust less than 10 km thick Itis created by partial melting of the Transition-Zone mantlealong the mid-oceanic ridges on top of the upwelling mantleplumes The total length of this submarine mountain rangethe so-called rift zone is about 80000 km The age of theoceanic crust is increasing with the perpendicular distancefrom the rift symmetrically on both sides The oldest large-scale oceanic crust is in the west Pacific and north-westAtlanticmdashboth are up to 180ndash200-million-year old Howeverparts of the eastern Mediterranean Sea are remnants of themuch older Tethys ocean at about 270-million-year old Thetypical rock types of the oceanic crust created along therifts are Midocean Ridge Basalts (MORB)They are relativelyenriched in lithophile elements with respect to the mantlefrom which they have been differentiated but they are much

depleted in them with respect to the continental crust Thetypical density of the oceanic crust is about 29 g cmminus3

The continental crust is thicker more heterogeneous andolder and has a more complex history with respect to theoceanic crust It forms continents and continental shelvescovered with shallow seas The bulk composition is graniticmore felsic with respect to oceanic crust Continental crustcovers about 40 of the Earth surface It is much thicker thanthe oceanic crust from 20 to 70 km The average density is27 g cmminus3 less dense than the oceanic crust and so to thecontrary of the oceanic crust the continental slabs rarelysubduct Therefore while the subducting oceanic crust getsdestroyed and remelted the continental crust persists Onaverage it has about 2 billion years while the oldest rockis the Acasta Gneiss from the continental root (craton) inCanada and is about 4-billion-year oldThe continental crustis thickest in the areas of continental collision and com-pressional forces where new mountain ranges are createdin the process called orogeny as in the Himalayas or inthe Alps There are the three main rock groups building upthe continental crust igneous (rocks which solidified from amolten magma (below the surface) or lava (on the surface))sedimentary (rocks that were created by the deposition of thematerial as disintegrated older rocks organic elements etc)and metamorphic (rocks that recrystallized without meltingunder the increased temperature andor pressure conditions)

There are several ways in which we can obtain informa-tion about the deep Earth Seismology studies the propaga-tion of the 119875 (primary longitudinal) and the 119878 (secondaryshear transversal) waves through the Earth and can constructthe wave velocities and density profiles of the Earth Itcan identify the discontinuities corresponding to mechanicalandor compositional boundaries The first order structureof the Earthrsquos interior is defined by the 1D seismologicalprofile called PREM Preliminary Reference Earth Model[12] The recent seismic tomography can reveal structures asLarge Low Shear Velocity Provinces (LLSVP) below Africaand central Pacific [13] indicating that mantle could be evencompositionally nonhomogeneous and that it could be testedvia future geoneutrino projects [14]

The chemical composition of the Earth is the subject ofstudy of geochemistry The direct rock samples are howeverlimited The deepest bore-hole ever made is 12 km in Kolapeninsula in Russia Some volcanic and tectonic processescan bring to the surface samples of deeper origin but oftentheir composition can be altered during the transport Thepure samples of the lower mantle are practically in existentWith respect to the mantle the composition of the crust isrelatively well known A comprehensive review of the bulkcompositions of the upper middle and lower crust werepublished by Rudnick and Gao [15] and Huang et al [16]

The bulk composition of the silicate Earth the so-calledBulk Silicate Earth (BSE) models describe the compositionof the Primitive Mantle the Earth composition after the coreseparation and before the crust-mantle differentiation Theestimates of the composition of the present-day mantle canbe derived as a difference between the mass abundances pre-dicted by the BSE models in the Primitive Mantle and those


observed in the present crust In this way the predictions oftheU andThmass abundances in themantle aremade whichare then critical in calculating the predicted geoneutrinosignal see Section 4

The refractory elements are those that have high conden-sation temperatures thus they did condensate from a hotnebula today form the bulk mass of the terrestrial planetsand are observed in equal proportions in the chondritesTheir contrary is volatile elements with low condensationtemperatures and which might have partially escaped fromthe planet U and Th are refractory elements while K ismoderately volatile All UTh andK are also lithophile (rock-loving) elements which in the Goldschmidt geochemicalclassification means elements tending to stay in the silicatephase (other categories are siderophile (metal-loving) chal-cophile (ore chalcogen-loving) and atmophilevolatile)

The most recent classification of BSE models was pre-sented by Sramek et al [14]

(i) Geochemical BSEModelsThesemodels rely on the fact thatthe composition of carbonaceous (CI) chondrites matchesthe solar photospheric abundances in refractory lithophilesiderophile and volatile elements These models assume thatthe ratios of Refractory Lithophile Elements (RLE) in the bulksilicate Earth are the same as in the CI chondrites and in thesolar photosphere The typical chondritic value of the bulkmass ThU ratio is 39 and KU sim 13000 The absolute RLEabundances are inferred from the available crust and uppermantle rock samples The theoretical petrological modelsand melting trends are taken into account in inferring thecomposition of the original material of the Primitive Mantlefrom which the current rocks were derived in the processof partial melting Among these models are McDonoughand Sun [17] Allegre et al [18] Hart and Zindler [19]Arevalo et al [20] and Palme and OrsquoNeill [21] The typicalU concentration in the bulk silicate Earth is about 20 plusmn 4 ppb

(ii) Cosmochemical BSE Models The model of Javoy et al[22] builds the Earth from the enstatite chondrites whichshow the closest isotopic similarity with mantle rocks andhave sufficiently high iron content to explain themetallic core(similarity in oxidation state)The ldquocollisional erosionrdquomodelofOrsquoNeill and Palme [23] is covered in this category aswell Inthis model the early enriched crust was lost in the collisionof the Earth with an external body In both of these modelsthe typical bulk U concentration is about 10ndash12 ppb

(iii) Geodynamical BSE Models These models are based onthe energetics of the mantle convection Considering thecurrent surface heat flux which depends on the radiogenicheat and the secular cooling the parametrized convectionmodels require higher contribution of radiogenic heat (andthus higher U and Th abundances) with respect to geo-andcosmochemical models The typical bulk U concentration is35 plusmn 4 ppb

The surface heat flux is estimated based on the measure-ments of temperature gradients along several thousands ofdrill holes along the globe The most recent evaluation ofthese data leads to the prediction of 47 plusmn 2 TW predicted

by J H Davies and D R Davies [24] consistent with theestimation of Jaupart et al [25] The relative contribution ofthe radiogenic heat from radioactive decays to this flux (so-calledUrey ratio) is not known and this is the key informationwhich can be pinned down by the geoneutrino measure-ments The geochemical cosmochemical and geodynamicalmodels predict the radiogenic heat of 20 plusmn 4 11 plusmn 2 33 plusmn3 TW and the corresponding Urey ratios of about 03 01and 06 respectively The Heat Producing Elements (HPE)predicted by these models are distributed in the crust andin the mantle The crustal radiogenic power was recentlyevaluated by Huang et al [16] as 68+14

minus11TW By subtracting

this contribution from the total radiogenic heat predicted bydifferent BSE models the mantle radiogenic power drivingthe convection and plate tectonics can be as little as 3 TW andas much as 23 TW To determine this mantle contribution isone of the main goals and potentials of neutrino geoscience

4 Geoneutrino Signal Prediction

The geoneutrino signal can be expressed in several ways Werecall that geoneutrinos are detected by the inverse beta decayreaction (see (1)) in which antineutrino interacts with a targetproton The most straightforward unit is the normalizedevent rate expressed by the so-called Terrestrial NeutrinoUnit (TNU) defined as the number of interactions detectedduring one year on a target of 1032 protons (sim1 kton of liquidscintillator) and with 100 detection efficiency Conversionbetween the signal 119878 expressed in TNU and the oscillatedelectron flavor flux 120601 (expressed in 10

6cmminus2 sminus1) is straight-forward [26] and requires a knowledge of the geoneutrinoenergy spectrum and the interaction cross section whichscales with the ]

119890energy

119878 (232Th) [TNU] = 407 sdot 120601 (

232Th)

119878 (238U) [TNU] = 128 sdot 120601 (

238U) (10)

In order to calculate the geoneutrino signal at a certainlocation on the Earthrsquos surface it is important to know theabsolute amount and the distribution ofHPE inside the EarthAs it was described in Section 3 we know relatively well suchinformation for the Earthrsquos crust but we lack it for themantleInstead the BSE models also described in Section 3 predictthe total amount of HPE in the silicate Earth (so excludingthemetallic core in which noHPE are expected)Thus in thegeoneutrino signal predictions the procedure is as followsFirst the signal from the crust is calculated Then the totalmass of the HPE concentrated in the crust is subtractedfrom the HPE mass predicted by a specific BSE model theremaining amount of HPE is attributed to be concentrated inthe mantle

Due to the chemical affinity of HPE the continentalcrust is their richest reservoir Thus for the experimentalsites built on the continental crust the total geoneutrinosignal is dominated by the crustal component It is importantto estimate it with the highest possible precision since themantle contribution can be extracted from the measured


Table 1 Expected geo-neutrino signal in Borexino and KamLANDDetails in text

Borexino KamLAND[TNU] [TNU]

LOC [32] 97 plusmn 13 177 plusmn 14

ROC [16] 137+28

minus2373+15

minus12

Total crust 234+31

minus26250+21

minus18

CLM [16] 22+31

minus1316+22

minus10

Mantle [16] 87 88Total 343

+44

minus29354+30

minus21

signal only after the subtraction of the expected crustalcomponent

The first estimation of the crustal geoneutrino signal[27] modeled the crust as a homogeneous 30 km thicklayer Since then several much more refined models havebeen developed In these models different geochemical andgeophysical data are used as input parameters The crust isdivided in finite volume voxels with surface area of either5∘

times 5∘ [28] 2∘ times 2

∘ [29ndash31] or most recently 1∘ times 1∘ [16]

The oceanic and continental crusts are treated separatelyThe continental crust is further divided in different layers asupper middle and lower continental crusts

On the sites placed on the continental crust a significantpart of the crustal signal comes from the area with a radiusof few hundreds of km around the detector [31] Thus ina precise estimation of the crustal geoneutrino signal it isimportant to distinguish the contribution from the local crust(LOC) and the rest of the crust (ROC) [32] In estimating theLOC contribution it is crucial to consider the compositionof real rocks surrounding the experimental site while forthe ROC contribution it is sufficient to take into account themean crustal compositions

Borexino and KamLAND the only two experimentswhich have provided geoneutrino measurements are placedin very different geological environments Borexino is placedon a continental crust in central Italy KamLAND is situatedin Japan in an area with very complicated geological struc-ture around the subduction zone In Table 1 we show theexpected geoneutrino signal for both experiments

The LOC contributions are taken from [32] The calcu-lations are based on six 2∘ times 2

∘ tiles around the detector asshown in Figure 2 The LOC contribution in Borexino basedon a detailed geological study of the LNGS area from [33] islow since the area is dominated by dolomitic rock poor inHPE The LOC contribution in KamLAND is almost doublesince the crustal rocks around the site are rich inHPE [29 34]

The ROC contributions shown in Table 1 are takenfrom [16] This recent crustal model uses as input severalgeophysical measurements (seismology gravitometry) andgeochemical data as the average compositions of the con-tinental crust [15] and of the oceanic crust [35] as wellas several geochemical compilations of deep crustal rocksThe calculated errors are asymmetric due to the log-normaldistributions of HPE elements in rock samples The authorsof [16] estimate for the first time the geoneutrino signal from

the Continental LithosphericMantle (CLM) a relatively thinrigid portion of the mantle which is a part of the lithosphere(see also Section 3)

The mantle contribution to the geoneutrino signal isassociated with a large uncertainty The estimation of themass of HPE in themantle is model dependentThe relativelywell known mass of HPE elements in the crust has to besubtracted from the total HPE mass predicted by a specificBSE model Since there are several categories of BSE models(see Section 3) the estimates of themass ofHPE in themantle(and thus of the radiogenic heat from the mantle) varly bya factor of about 8 [14] In addition the geoneutrino signalprediction depends on the distribution of HPE in the mantlewhich is unknown As it was described in Section 3 there areindications of compositional inhomogeneities in the mantlebut this is not proved and several authors prefer amantle withhomogeneous composition Extremes of the expectedmantlegeoneutrino signal with a fixed HPE mass can be defined[14 32]

(i) Homogeneous Mantle The case when the HPE are dis-tributed homogeneously in the mantle corresponds to themaximal high geoneutrino signal

(ii) Sunken Layer The case when the HPE are concentratedin a limited volume close to the core-mantle boundarycorresponds to theminimal low geoneutrino signal

(iii) Depleted Mantle + Enriched Layer (DM + EL) This isa model of a layered mantle with the two reservoirs (DMand EL) in which the HPE are distributed homogeneouslyThe total mass of HPE in the DM + EL corresponds to achosen BSE model There are estimates of the compositionof the upper mantle (DM) from which the oceanic crust(composed of Mid-Ocean Ridge Basalts MORB) has beendifferentiated [36ndash38] Since in the process of differentiationthe HPE are rather concentrated in the liquid part theresidual mantle remains depleted in HPE The measuredMORB compositions indicate that their source must be infact depleted in HPE with respect to the rest of the mantleThe mass fraction of the EL is not well defined and in thecalculations of Sramek et al [14] a 427 km thick EL placedabove the core-mantle boundary has been used

An example of the estimation of the mantle signal forBorexino and KamLAND given in Table 1 is taken from [16]

5 Current Experiments

At the moment there are only two experiments measuringthe geoneutrino s signals KamLAND [41 42] in the Kamiokamine in Japan and Borexino [43ndash45] at Gran Sasso NationalLaboratory in central Italy Both experiments are based onlarge volume spherical detectors filled with 287 ton and1 kton respectively of liquid scintillatorThey both are placedin underground laboratories in order to reduce the cosmicray fluxes a comparative list of detectorsrsquo main features isreported in Table 2

51 KamLAND The Kamioka Liquid scintillator ANtineu-trino Detector (KamLAND) was built starting from 1999 in


(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)

Figure 2 The map of six 2∘ times 2∘ tiles from which the LOC geoneutrino signal (see Table 1) is calculated for the Borexino ((a) from [39]) andKamLAND ((b) from [40]) sites

Table 2 Main characteristics of the Borexino and KamLAND detectors

Borexino KamLANDDepth 3600mwe (120601

120583= 12mminus2 hminus1 ) 2700mwe (120601

120583= 54 mminus2 hminus1)

Scintillator mass 278 ton (PC + 15 gl PPO) 1 kt (80 dodec + 20 PC + 14 gl PPO)Inner detector 13m sphere 2212 810158401015840 PMTrsquos 18m sphere 1325 1710158401015840 + 554 2010158401015840 PMTrsquosOuter detector 24 kt HP water + 208 810158401015840 PMTrsquos 32 kt HP water + 225 2010158401015840 PMTrsquosEnergy resolution 5 at 1MeV 64 at 1MeVVertex resolution 11 cm at 1MeV 12 cm at 1MeVReactors mean distance sim1170 km sim180 km

a horizontal mine in the Japanese Alps at a depth of 2700meters water equivalent (mwe) It aimed at a broad experi-mental program ranging fromparticle physics to astrophysicsand geophysics

The heart of the detector is a 1 kton of highly purifiedliquid scintillator made of 80 dodecane 20 pseudoc-umene and 136 plusmn 003 gL of 25-Diphenyloxazole (PPO)It is characterized by a high scintillation yield high lighttransparency and a fast decay time all essential requirementsfor good energy and spatial resolutions The scintillator isenclosed in a 13m spherical nylon balloon suspended ina nonscintillating mineral oil by means of Kevlar ropesand contained inside a 9m radius stainless-steel tank (seeFigure 3) An array of 1325 of ldquo17rdquo PMTs and 554 of ldquo20rdquo PMTs(inner detector) is mounted inside the stainless-steel vesselviewing the center of the scintillator sphere and providinga 34 solid angle coverage The containment sphere issurrounded by a 32 kton cylindrical water Cherenkov outerdetector that shields the external background and acts as anactive cosmic-ray veto

The KamLAND detector is exposed to a very large fluxof low-energy antineutrinos coming from the nuclear reactorplants Prior to the earthquake and tsunami of March 2011one-third of all Japanese electrical power (which is equiv-alent to 130 GW thermal power) was provided by nuclearreactors The fission reactors release about 1020 ]

119890GWminus1 sminus1

that mainly come from the 120573-decays of the fission productsof 235U 238U 239Pu and 241Pu used as fuels in reactor coresThe mean distance of reactors from KamLAND is sim180 km

Figure 3 Schematic view of the KamLAND detector

Since 2002 KamLAND is detecting hundreds of ]119890interac-

tions per yearThe first success of the collaboration a milestone in

the neutrino and particle physics was to provide a directevidence of the neutrino flavor oscillation by observing


the reactor ]119890disappearance [46] and the energy spectral

distortion as a function of the distance to ]119890-energy ratio [47]

The measured oscillation parameters Δ119898221

and tan2(12057912)

were found under the hypothesis of CPT invariance inagreement with the Large Mixing Angle (LMA) solution tothe solar neutrino problem and the precision of the Δ1198982

21

was greatly improved In the following years the oscillationparameters were measured with increasing precision [48]

KamLAND was the first experiment to perform exper-imental investigation of geoneutrino s in 2005 [49] Anupdated geoneutrino analysis was released in 2008 [48]An extensive liquid-scintillator purification campaign toimprove its radio-purity took place in years 2007ndash2009 Con-sequently a new geoneutrino observation at 99997CLwas achieved in 2011 with an improved signal-to-backgroundratio [50] Recently after the earthquake and the consequentFukushima nuclear accident occurred in March 2011 allJapanese nuclear reactors were temporarily switched off for asafety review Such situation allowed for a reactor on-off studyof backgrounds and also yielded an improved sensitivity for ]

119890

produced by other sources like geoneutrino s A new resulton geoneutrino s has been released recently in March 2013[51]

In September 2011 the KamLAND-Zen ]-less doublebeta-decay search was launched A 120573120573 source made up by13 ton of Xe-loaded liquid scintillator was suspended insidea 308m diameter inner balloon placed at the center of thedetector (see Figure 3) A new lower limit for the ]-lessdouble-beta decay half-life was published in 2013 [52]

52 Borexino The Borexino detector was built starting from1996 in the underground hall C of the Laboratori Nazionalidel Gran Sasso in Italy with the main scientific goal to mea-sure in real-time the low-energy solar neutrinos Neutrinosare even trickier to be detected than antineutrinos In aliquid scintillator ]

119890rsquos give a clean delayed-coincidence tag

which helps to reject backgrounds see Section 61 Neutrinosinstead are detected through their scattering off electronswhich does not provide any coincidence tag The signal isvirtually indistinguishable from any background giving a 120573120574decays in the same energy range For this reason an extremeradio-purity of the scintillator a mixture of pseudocumeneand PPO as fluor at a concentration of 15 gL was an essentialprerequisite for the success of Borexino

For almost 20 years the Borexino collaboration has beenaddressing this goal by developing advanced purificationtechniques for scintillator water and nitrogen and by exploit-ing innovative cleaning systems for each of the carefullyselected materials A prototype of the Borexino detector theCounting Test Facility (CTF) [53 54] was built to prove thepurification effectiveness The conceptual design of Borexinois based on the principle of graded shielding demonstratedin Figure 4 A set of concentric shells of increasing radio-purity moving inwards surrounds the inner scintillator coreThe core is made of sim280 ton of scintillator contained ina 125 120583m thick nylon Inner Vessel (IV) with a radius of425m and shielded from external radiation by 890 ton ofinactive buffer fluid Both the active and inactive layers are

Borexino detectorExternal water

tankRopes

InternalPMTs

Steel platesfor extra shielding

Water

BufferScintillator

MuonPMTs

Stainless steel sphereNylon outer vessel

Nylon inner vesselFiducial volume

Figure 4 Schematic diagram of the Borexino detector

contained in a 137m diameter Stainless Steel Sphere (SSS)equipped with 2212 ldquo8rdquo PMTs (Inner Detector) A cylindricaldome with diameter of 18m and height of 169m enclosesthe SSS It is filled with 24 kton of ultrapure water viewedby 208 PMTs defining the Outer DetectorThe external waterserves both as a passive shield against external backgroundsources mostly neutrons and gammas and also as an activeCherenkov veto system tagging the residual cosmic muonscrossing the detector

After several years of construction the data takingstarted in May 2007 providing immediately evidence of theunprecedented scintillator radio purity Borexino was thefirst experiment to measure in real time low-energy solarneutrinos below 1MeV namely the 7Be-neutrinos [55 56]In May 2010 the Borexino Phase 1 data taking period wasconcluded Its main scientific goal the precision 7Be-]measurement has been achieved [57] and the absence of theday-night asymmetry of its interaction rate was observed[58] In addition other major goals were reached as the firstobservation of the 119901119890119901-] and the strongest limit on the CNO-] [59] the measurement of 8B-] rate with a 3MeV energythreshold [60] and in 2010 the first observation of geoneu-trino s with high statistical significance at 99997CL [61]

In 2010-2011 six purification campaigns were performedto further improve the detector performances and in October2011 the Borexino Phase 2 data taking period was started Anew result on geoneutrino s has been released in March 2013[62] Borexino continues in a rich solar neutrino programincluding two evenmore challenging targets 119901119901 and possiblyCNO neutrinos In parallel the Borexino detector will beused in the SOX project a short baseline experiment aimingat investigation of the sterile-neutrino hypothesis [63]

6 Geoneutrino Analysis

61 The Geoneutrino Detection The hydrogen nuclei that arecopiously present in hydrocarbon (C

119899H2119899) liquid scintillator

detectors act as target for electron antineutrinos in the inversebeta decay reaction shown in (1) In this process a positronand a neutron are emitted as reaction products The positronpromptly comes to rest and annihilates emitting two 511 keV


Table 3Themost important backgrounds in geoneutrinomeasure-ments of Borexino [62] and KamLAND [51]

Borexino KamLANDPeriod Dec 07ndashAug 12 Mar 02ndashNov 12Exposure (proton sdot year) (369 plusmn 016) 1031 (49 plusmn 01) 1032

Reactor-]119890events (no osc) 604 plusmn 41 3564 plusmn 145

13C(120572 119899) 16O events 013 plusmn 001 2071 plusmn 2639Li-8He events 025 plusmn 018 316 plusmn 19Accidental events 0206 plusmn 0004 1255 plusmn 01Total non-]

119890backgrounds 070 plusmn 018 3641 plusmn 305

120574-rays yielding a prompt event with a visible energy 119864promptdirectly correlated with the incident antineutrino energy 119864]

119890

119864prompt = 119864]119890

minus 0784MeV (11)

The emitted neutron keeps initially the information aboutthe ]119890direction but unfortunately the neutron is typically

captured on protons only after a quite long thermalizationtime (120591 = 200ndash250 120583s depending on scintillator) Duringthis time the directionalitymemory is lost inmany scatteringcollisions When the thermalized neutron is captured onproton it gives a typical 222MeV deexcitation 120574-ray whichprovides a coincident delayed event The pairs of time andspatial coincidences between the prompt and the delayedsignals offer a clean signature of ]

119890interactions very different

from the ]119890scattering process used in the neutrino detection

62 Background Sources The coincidence tag used in theelectron antineutrino detection is a very powerful tool inbackground suppressionThemain antineutrino backgroundin the geoneutrinomeasurements results from nuclear powerplants while negligible signals are due to atmosphericand relic supernova ]

119890 Other nonantineutrino background

sources can arise from intrinsic detector contaminationsfrom random coincidences of noncorrelated events and fromcosmogenic sources mostly residual muons An overviewof the main background sources in the Borexino and Kam-LAND geoneutrino measurements is presented in Table 3

A careful analysis of the expected reactor ]119890rate at a

given experimental site is crucial The determination of theexpected signal from reactor ]

119890rsquos requires the collection of

the detailed information on the time profiles of the thermalpower and nuclear fuel composition for all the reactorsespecially for the nearby ones The Borexino and KamLANDcollaborations are in strict contact with the InternationalAgency of Atomic Energy (IAEA) and the Consortium ofJapanese Electric Power Companies respectively

A new recalculation [65 66] of the ]119890spectra per fission

of 235U 238U 239Pu and 241Pu isotopes predicted a sim3 fluxincrease relative to the previous calculations As a conse-quence all past experiments at short-baselines appear now tohave seen fewer ]

119890than expected and this problemwas named

the Reactor Neutrino Anomaly [67] It has been speculatedthat it may be due to some not properly understood systemat-ics but in principle an oscillation into an hypothetical heavysterile neutrino state with Δ119898

2

sim 1 eV2 could explain this

90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100

0minus180 minus120 minus60 0 60 120 180

[1TNU = 1 event1032 target protonsyear]

Figure 5 Reactor ]119890signal (expressed in TNU) in the world as in

the middle of 2012 calculated in [64]

anomaly In the KamLAND analysis the cross section perfission for each reactor was normalized to the experimentalfluxesmeasured by Bugey-4 [67]TheBorexino analysis is notaffected by this effect since the absolute reactor antineutrinosignal was left as a free parameter in the fitting procedureand the spectral shape of the new parametrization is notsignificantly different up to 75MeV from the previous ones

The expected reactor ]119890signal in the world [64] is shown

in Figure 5 it refers to the middle of 2012 when the Japanesenuclear power plants were switched off The red spot close toJapan is due to theKorean reactorsTheworld average nuclearenergy production is of the order of 1 TW a 2 of the Earthsurface heat flux There are no nuclear power plants in Italyand the reactor ]

119890flux in Borexino is a factor of 4-5 lower than

in the KamLAND site during normal operating conditionA typical rate of sim5 and sim21 geo-] eventsyear with

100 efficiency is expected in the Borexino and KamLANDdetector for a 4m and 6m fiducial volume cut respectivelyThis signal is very faint and also the non-]

119890-induced back-

grounds have to be incredibly small Random coincidencesand (120572 n) reactions in which 120572rsquos are mostly due to the210Po decay (belonging to the 238U chain) can mimic thereaction of interest The 120572-background was particularly highfor the KamLAND detector at the beginning of data taking(sim103 cpdton) but it has been successfully reduced by afactor 20 thanks to the 2007ndash2009 purification campaignsBackgrounds faking ]

119890interactions could also arise from

cosmic muons and muon induced neutrons and unstablenuclides like 9Li and 8He having an 120573+neutron decaybranch Very helpful to this respect is the rock overlayof 2700mwe for the KamLAND and 3600mwe for theBorexino experimental site reducing this background by afactor up to 10

6 A veto applied after each muon crossingthe outer andor the inner detectors makes this backgroundalmost negligible

63 Current Experimental Results Both Borexino [62] andKamLAND [51] collaborations released new geoneutrinoresults in March 2013 and we describe them in more detailbelowThe corresponding geoneutrino signals and signal-to-background ratios are shown in Table 3

The KamLAND result is based on a total live-time of 2991days collected between March 2002 and November 2012


060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year

Period 1 Period 2 Period 3

KamLAND dataExpected reactor e + backgrounds + geo eExpected reactor e + backgroundsExpected reactor e

(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)

01 02 03 04 05 06Expected rate (eventsday)

(b)

Figure 6 (a) Event rate in the KamLAND detector as a function of time in the 09ndash26 energy window (b) The excess of events with respectto the expected background rate is constant in time and attributed to the geo-] signal taken from [51]

In this 10-year time window the backgrounds and detectorconditions have changed After the April 2011 earthquake theJapanese nuclear energy production was strongly reducedand in particular in the April to June 2012 months all theJapanese nuclear reactors were switched off with the onlyexception of the Tomary plant which is in any case quite far(sim600 km) from theKamLANDsiteThis reactor-off statisticswas extremely helpful to check all the other backgrounds andit is included in the present data sample even if with a reducedFiducial Volume (FV) In fact because of the contemporarypresence of the Inner Balloon containing the Xe loadedscintillator at the detector center the central portion of thedetector was not included in the analysis

The ]119890event rate in the KamLAND detector and in the

energy window 09ndash26MeV as a function of time is shown inFigure 6(a)Themeasured excess of events with respect to thebackground expectations is constant in time as highlightedin Figure 6(b) and is attributed to the geoneutrino signal

To extract the neutrino oscillation parameters and thegeoneutrino fluxes the ]

119890candidates are analyzed with an

unbinned maximum likelihood method incorporating themeasured event rates the energy spectra of prompt candi-dates and their time variationsThe total energy spectrum ofprompt events and the fit results are shown in Figure 7(b) Byassuming a chondriticThUmass ratio of 39 the fit results in116+28

minus27geoneutrino events corresponding to a total oscillated

flux of 34+08minus08

sdot106 cmminus2 sminus1 It is easy to demonstrate that given

the geoneutrino energy spectrum the chondritic mass ratioand the inverse beta decay cross section a simple conversionfactor exists between the fluxes and the TNU units 1 TNU =

0113 sdot 106]119890cmminus2 sminus1 By taking this factor we could translate

the KamLAND result to (30 plusmn 7)TNUWhile the precision of the KamLAND result is mostly

affected by the systematic uncertainties arising from the size-able backgrounds the extremely low background togetherwith the smaller fiducial mass (see Tables 3 and 4) makesthe statistical error largely predominant in the Borexinomeasurement

Table 4 Measured geo-neutrino signal in Borexino [62] andKamLAND [51]

Borexino KamLAND

Period Dec 07ndashAug 12 Mar 02ndashNov 12Exposure (proton sdot year) (369 plusmn 016) 1031 (49 plusmn 01) 1032

Geo-] events 143 plusmn 44 116+28

minus27

Geo-] signal [TNU] 388 plusmn 12 30 plusmn 7Geo-] flux (oscill)[sdot106 cmminus2 sminus1] 44 plusmn 14 34 plusmn 08

Geo-] signal(not-oscillanti-] background) 023 0032

Geo-] signal(non anti-]background) 204 032

The Borexino result shown in Figure 7(a) refers to thestatistics collected from December 2007 to August 2012 Thelevels of background affecting the geo-] analysis were almostconstant during the whole data taking the only differencebeing an increased radon contamination during the testphases of the purification campaigns These data periods arenot included in the solar neutrino analysis but can be usedin the geoneutrino analysis A devoted data selection cutswere adopted to make the increased background level notsignificant in particular an event pulse-shape analysis andan increased energy threshold have been applied for delayedcandidates

The Borexino collaboration selected 46 antineutrino can-didates (Figure 7(a)) among which 333 plusmn 24 events wereexpected from nuclear reactors and 070plusmn018 from the non-]119890backgrounds An unbinned maximal likelihood fit of the

light-yield spectrum of prompt candidates was performedwith the ThU mass ratio fixed to the chondritic value of 39and with the number of events from reactor antineutrinosleft as a free parameter As a result the number of observedgeoneutrino events is 143plusmn 44 in (369plusmn 016) sdot 1031 proton sdotyear exposure This signal corresponds to ]

119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500

Light yield of prompt event (pe)

Borexino data

Best fit geo- eBest fit reactor- e

Reactor- e signalGeo- e signal

Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)

Best-fit reactor eAccidental13C(120572 n)16O

Best-fit geo e

Even

tS02

MeV

Best-fit reactor e + BG+ best-fit geo e

(b)

Figure 7 Prompt event energy spectrum measured in Borexino (a) and in KamLAND (b) The Borexino collaboration quotes the promptevent energy as total number of photoelectrons detected by the PMTs the conversion factor being approximately 500 pe1MeV

andThchains respectively of 120601(U) = (24plusmn07)sdot106 cmminus2 sminus1

and 120601(Th) = (20 plusmn 06) sdot 106 cmminus2 sminus1 and to a total measured

normalized rate of (388 plusmn 12) TNUThe measured geoneutrino signals reported in Table 4

can be compared with the expectations reported in Table 1The two experiments placed very far from each other havepresently measured the geoneutrino signal with a highstatistical significance (at sim48120590CL) and in a good agree-ment with the geological expectations This is an extremelyimportant point since it is confirming both that the geologicalmodels are working properly and that the geoneutrino sare a reliable tools to investigate the Earth structure andcomposition

64 Geological Implications In the standard geoneutrinoanalysis the ThU bulk mass ratio has been assumed to be39 a value of this ratio observed in CI chondritic meteoritesand in the solar photosphere and a value assumed by thegeochemical BSE models However this value has not yetbeen experimentally proven for the bulk Earth The knowl-edge of this ratio would be of a great importance in a viewof testing the geochemical models of the Earth formationand evolution It is in principle possible to measure thisratio with geoneutrino s exploiting the different end-pointsof the energy spectra from U and Th chains (see Figure 1)A mass ratio of 119898(Th)119898(U) = 39 corresponds to the signalratio 119878(U)119878(Th) sim 366 Both KamLAND and Borexinocollaborations attempted an analysis in which they tried toextract the individual U and Th contributions by removingthe chondritic constrain from the spectral fit In Figure 8 theconfidence-level contours from such analyses are shown forBorexino (a) and for KamLAND (b) Borexino has observedthe central value a 119878(U)119878(Th) of sim25 while KamLAND ofsim145 but they are not in contradiction since the uncertainties

are still very large and the results not at all conclusive Boththe best fit values are compatible at less than 1120590 level with thechondritic values

As discussed in Section 3 the principal goal of geoneu-trino measurements is to determine the HPE abundances inthe mantle and from that to extract the strictly connectedradiogenic power of the Earth The geoneutrino fluxes fromdifferent reservoirs sum up at a given site so the mantlecontribution can be inferred from the measured signal bysubtracting the estimated crustal (LOC + ROC) components(Section 4) Considering the expected crustal signals fromTable 1 and the measured geoneutrino signals from Table 4such a simple subtraction results in mantle signals measuredby KamLAND 119878

KLMantle and Borexino 119878BXMantle of

119878KLMantle = (50 plusmn 73) TNU

119878BXMantle = (154 plusmn 123) TNU

(12)

A graphical representation of the different contributions inthe measured signals is shown in Figure 9

TheKamLANDresult seems to highlight a smallermantlesignal than the Borexino one Such a result pointing towardsmantle inhomogeneities is very interesting from a geologicalpoint of view but the error bars are still too large to getstatistically significant conclusions Indeed recent modelspredicting geoneutrino fluxes from themantle not sphericallysymmetric have been presented [14] They are based on thehypothesis indicated by the geophysical data that the LargeLow Shear Velocity Provinces (LLSVP) placed at the baseof the mantle beneath Africa and the Pacific represent alsocompositionally distinct areas In a particular the TOMOmodel [14] predicts a mantle signal in Borexino site higherby 2 than the average mantle signal while a decrease of85 with respect to the average is expected for KamLAND


S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th

minus1 minus05 0 05 1(NU minus NTh )(NU + NTh )

683954997

(b)

Figure 8 (a)The 683 954 and 997 contour plots of theTh versus U signal expressed in TNU units in the Borexino geoneutrino analysis[62] the dashed blue line is the expectation for a chondritic ThU mass ratio of 39 (b) the same confidence level contours are shown for theKamLAND analysis [51] expressed in number of total events versus the normalized difference of the number of events from U andTh Thevertical dashed line represents the chondritic ratio of 39 while the shadowed area on this line is the prediction of the BSE model from [17]

60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND

Figure 9 The measured geo-] signal in Borexino and KamLANDcompared to the expected fluxes from Table 1 area with horizontalstripes = LOC area with oblique stripes = ROC green solid area =CLMThe dotted area is the excess of signal which could correspondto the convective mantle contributions The sum of the CLM andthe convective mantle contributions corresponds to the total mantlesignal as from (12)

We have performed a combined analysis of the Borexino andKamLAND data in the hypothesis of a spherically symmetricmantle or a not homogeneous one as predicted by the TOMOmodel

The Δ1205942 profiles for both models are shown in Figure 10For the homogeneous mantle we have obtained the signal119878SYMMantle of

119878SYMMantle = (77 plusmn 62) TNU (13)

Instead when the Borexino and KamLAND mantle signalshave been constrained to the ratio predicted by the TOMOmodel the mean mantle signal 119878TOMO

Mantle results to be

119878TOMOMantle = (84

+66

minus67) TNU (14)

There is an indication for a positive mantle signal but onlywith a small statistical significance of about 15120590CL Thecentral values are quite in agreement with the expectationshown in Table 1 A slightly higher central value is observedfor the TOMO model We stress again the importance ofa detailed knowledge of the local crust composition andthickness in order to deduce the signal coming from themantle from the measured geoneutrino fluxes

In Figure 11 we compare the measured mantle signal119878SYMMantle from (13) with the predictions of the three categoriesof the BSE models according to [14] which we have discussedin Section 4 that is the geochemical cosmochemical andgeodynamical ones For each BSE model category fourdifferent HPE distributions through the mantle have beenconsidered a homogeneous model and the three DM + ELmodels with the three different depletedmantle compositionsas in [36ndash38] All the Earth models are still compatibleat 2120590 level with the measurement as shown in Figure 11even if the present combined analysis slightly disfavorsthe geodynamical models We remind that these modelsare based on the assumption that the radiogenic heat hasprovided the power to sustain the mantle convection over thewhole Earth story It has been recently understood [68] the


25

2

15

1

05

0

Δ1205942

0 2 4 6 8 10 12 14 16 18Mantle signal (TNU)

Figure 10 Δ1205942 profile for the mantle signal in the Borexino +KamLAND combined analysis The black continuous line assumesa spherically symmetric mantle while the dashed blue line anonhomogeneous TOMOmodel from [14]

30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)

Cosmochemical Geochemical Geodynamical

Homogeneous mantleDM + EL 1

DM + EL 2DM + EL 3

Figure 11 The measured geoneutrino signal from the Borexino +KamLAND combined analysis under the assumption of a spheri-cally symmetricmantle (see (13)) is comparedwith the predictions ofdifferent Earthrsquos models from [14] The three DM + EL distributionsof the HPE elements in the mantle correspond to the depletedmantle compositions from [36ndash38] respectively

importance of thewater orwater vapor embedded in the crustand mantle to decrease the rock viscosity and so the energysupply required to promote the convection If this is the casethe geodynamical models are going to be reconciled with thegeochemical ones

It is in principle possible to extract from the measuredgeoneutrino signal the Earthrsquos radiogenic heat power Thisprocedure is however not straightforward the geoneutrinoflux depends not only on the total mass of HPE in the Earthbut also on their distributions which is model dependentThe HPE abundances and so the radiogenic heat in the crustare rather well known as discussed in Sections 3 and 4As the main unknown remains the radiogenic power of theEarthrsquos mantle Figure 12 summarizes the analysis we have

30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)

0 5 10 15 20Measured mantle signal (TNU)

Total sun

Total homo

Th-sun Th-homo U-homoU-sun

Figure 12 The mantle radiogenic heat power from U and Thas a function of the measured geoneutrino signal the solid linesrepresent the sunken-layer model while the dotted lines the homo-geneousmantle (see Section 4)The green and the blue lines indicatethe individualTh andU contributions respectively while the brownlines show the total signalThemeasured mantle geoneutrino signal119878SYMMantle from a combined Borexino + KamLAND analysis is shownby the vertical solid orange line the corresponding 1120590 band is shownby a filled triangular area The arrows on the vertical 119910-axis indicatethe radiogenic heat corresponding to the best fit geoneutrino signalDetails in text

performed in order to extract the mantle radiogenic heatfrom the measured geoneutrino signals

The geoneutrino luminosity Δ119871 (]119890emitted per unit time

from a volume unit so-called voxel) is related [2] to theU andThmasses Δ119898 contained in the respective volume

Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)

where the masses are expressed in units of 1017 kg and theluminosity in units of 1024 sminus1

The measured geoneutrino signal at a given site canbe deduced by summing up the U and Th contributionsfrom individual voxels over the whole Earth [14 26 2932] and by weighting them by the inverse squared-distance(geometrical flux reduction) and by the oscillation survivalprobability We have performed such an integration for themantle contribution to the geoneutrino signal We havevaried the U and Th abundances (with a fixed chondriticmass ratio ThU = 39) in each voxel The homogeneous andsunken layer models of the HPE distributions in the mantle(Section 4) were taken into account separately For eachiteration of different U andTh abundances and distributionsthe total mantle geoneutrino signal (taking into account (15))and the U + Th radiogenic heat power from the mantle(considering equation (4) from [2]) can be calculated Theresult is shown in Figure 12 showing the U + Th mantleradiogenic heat power as a function of the measured mantlegeoneutrino signalThe solid lines represent the sunken-layermodel while the dotted lines the homogeneous mantle The


individual U and Th contributions as well as their sums areshownThemeasuredmantle signal 119878SYMMantle = (77plusmn62)TNUfrom the combined Borexino andKamLANDanalysis quotedin (13) is demonstrated on this plot by the vertical solid(orange) line indicating the central value of 77 TNUwhile thefilled (light brown) triangular area corresponds to plusmn62TNUband of 1120590 error The central value of 119878SYMMantle = 77 TNUcorresponds to the mantle radiogenic heat from U andTh of 75ndash105 TW (orange double arrow on 119910-axis) forsunken-layer and homogeneous HPE extreme distributionsrespectively If the error of the measured mantle geoneutrinosignal is considered (plusmn62TNU) the corresponding intervalof possible mantle radiogenic heat is from 2 to 195 TWindicated by the black arrow on 119910-axis

7 Conclusions and Future Perspectives

The two independent geoneutrino measurements from theBorexino and KamLAND experiments have opened the doorto a new interdisciplinary field the neutrino geoscienceTheyhave shown that we have a new tool for improving ourknowledge on the HPE abundances and distributions Thefirst attempts of combined analysis has appeared [26 32 5062] showing the importance of multisite measurements Thefirst indication of a geoneutrino signal from the mantle hasemergedThe present data seem to disfavor the geodynamicalBSE models in agreement with the recent understanding ofthe important role of water in the heat transportation engine

These results together with the first attempts to directlymeasure the ThU ratio are the first examples of geologicallyrelevant outcomes But in order to find definitive answersto the questions correlated to the radiogenic heat and HPEabundances more data are needed Both Borexino andKamLAND experiments are going on to take data and anew generation of experiments using liquid scintillators isforeseenOne experimental project SNO+ inCanada is in anadvanced construction phase and a new ambitious projectDaya-Bay 2 in China mostly aimed to study the neutrinomass hierarchy has been approved Other interesting pro-posals have been presented LENA at Pyhasalmi (Finland) orFrejus (France) and Hanohano in Hawaii

The SNO+ experiment in the Sudbury mine in Canada[69 70] at a depth of 6080mwe is expected to start thedata-taking in 2014-2015 The core of the detector is made ofsim780 ton of LAB (linear alkylbenzene) with the addition ofPPO as fluor A rate of sim20 geoneutrino syear is expectedand the ratio of geoneutrino to reactor ]

119890events should be

around sim12 The site is located on an old continental crustand it contains significant quantities of felsic rocks whichare enriched in U and Th Moreover the crust is particularlythick (ranging between 442 km and 414 km) approximately40 thicker than the crust surrounding the Gran Sasso andKamioka sites For these reasons a strong LOC signal isexpected around 19 TNU A very detailed study of the localgeology ismandatory to allow themeasurement of themantlesignal

Themain goal of the Daya Bay 2 experiment in China [71]is to determine the neutrino mass hierarchyThanks to a very

large mass of 20 kton it would detect up to 400 geoneutrino sper year A few percent precision of the total geoneutrino fluxmeasurement could be theoretically reached within the firstcouple of years and the individual U and Th contributionscould be determined as well Unfortunately the detector siteis placed on purpose very close to the nuclear power plantThus under the normal operating conditions the reactor]119890flux is huge (sim40 detected eventsday) Data interesting

for the geoneutrino studies could be probably taken only incorrespondence with reactor maintenance or shutdowns

LENA is a proposal for a huge 50 kton liquid scintillatordetector aiming at the geoneutrinomeasurement as one of themain scientific goals [72] Two experimental sites have beenproposed Frejus in France or Pyhasalmi in Finland From thepoint of view of the geoneutrino study the site in Finlandwould be strongly preferable since Frejus is very close tothe French nuclear power plants LENA would detect about1000 geoneutrino events per year a few percent precision onthe geoneutrino flux could be reached within the first fewyears an order ofmagnitude improvementwith respect to thecurrent experimental resultsThanks to the largemass LENAwould be able tomeasure theThU ratio after 3 years with 10-11 precision in Pyhasalmi and 20 precision in Frejus

Another very interesting project is Hanohano [73] inHawaii placed on a thin HPE depleted oceanic crust Themantle contribution to the total geoneutrino flux should bedominant sim75 A tank of 26m in diameter and 45m tallhousing a 10 kton liquid scintillator detector would be placedvertically on a 112m long barge and deployed in the deepocean at 3 to 5 kmdepthThe possibility to build a recoverableand portable detector is part of the project A very highgeoneutrino event rate up to about sim100 per year would beobserved with a geoneutrino to reactor-]

119890event rate ratio

larger than 10In conclusion the new interdisciplinary field has been

formed The awareness of the potential to study our planetwith geoneutrino s is increasing within both geological andphysical scientific communities This may be the key step inorder to promote the new discoveries about the Earth and thenew projects measuring geoneutrinos

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] C Rolfs and W Rodney Cauldron in the Cosmos NuclearAstrophysics University of Chicago Press 1988

[2] G Fiorentini M Lissia and F Mantovani ldquoGeo-neutrinos andEarthrsquos interiorrdquo Physics Reports vol 453 no 5-6 pp 117ndash1722007

[3] S Enomoto Neutrino geophysics and observation of geo-neutrinos at KamLAND [PhD thesis] Tohoku UniversityHonshu Japan 2005

[4] S Enomoto ldquoUsing neutrinos to study the Earth geo-neutrinosrdquo in Proceedings of the NeuTel Conference VeniceItaly 2009


[5] G L Fogli E Lisi A Marrone D Montanino A Palazzo andA M Rotunno ldquoGlobal analysis of neutrino masses mixingsand phases entering the era of leptonic CP violation searchesrdquoPhysical Review D vol 86 no 1 Article ID 013012 10 pages2012

[6] J N Connelly M Bizzarro A N Krot A Nordlund DWielandt and M A Ivanova ldquoThe absolute chronology andthermal processing of solids in the solar protoplanetary diskrdquoScience vol 338 no 6107 pp 651ndash655 2012

[7] S A Wilde J W Valley W H Peck and C M GrahamldquoEvidence from detrital zircons for the existence of continentalcrust and oceans on the Earth 44 Gyr agordquoNature vol 409 no6817 pp 175ndash178 2001

[8] T Klelne C Munker K Mezger and H Palme ldquoRapid accre-tion and early core formation on asteroids and the terrestrialplanets from Hf-W chronomebyrdquo Nature vol 418 no 6901 pp952ndash955 2002

[9] V R Murthy W van Westrenen and Y Fei ldquoExperimentalevidence that potassium is a substantial radioactive heat sourcein planetary coresrdquoNature vol 423 no 6936 pp 163ndash165 2003

[10] W F McDonough ldquoCompositional model for the Earthrsquos corerdquoinTheMantle and Core R W Carlson Ed vol 2 of Treatise onGeochemistry pp 547ndash568 Elsevier Oxford UK 2003

[11] J M Herndon ldquoSubstructure of the inner core of the earthrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 93 no 2 pp 646ndash648 1996

[12] A M Dziewonski and D L Anderson ldquoPreliminary referenceEarth modelrdquo Physics of the Earth and Planetary Interiors vol25 no 4 pp 297ndash356 1981

[13] Y Wang and L Wen ldquoMapping the geometry and geographicdistribution of a very low velocity province at the base of theEarthrsquos mantlerdquo Journal of Geophysical Research B vol 109 no10 Article ID B10305 18 pages 2004

[14] O Sramek W F McDonough E S Kite V Lekic S T Dyeand S Zhong ldquoGeophysical and geochemical constraints ongeo-neutrino fluxes from Earthrsquos mantlerdquo Earth and PlanetaryScience Letters vol 361 pp 356ndash366 2013

[15] R L Rudnick and S Gao ldquoComposition of the continentalcrustrdquo in The Crust R L Rudnick Ed vol 3 of Treatise onGeochemistry pp 1ndash64 Elsevier Oxford UK 2003

[16] Y Huang V Chubakov F Mantovani R L Rudnick and W FMcDonough ldquoA reference Earth model for the heat-producingelements and associated geoneutrino fluxrdquo Geochemistry Geo-physics Geosystems vol 14 no 6 pp 2003ndash2029 2013

[17] W F McDonough and S-S Sun ldquoThe composition of theEarthrdquo Chemical Geology vol 120 no 3-4 pp 223ndash253 1995

[18] C J Allegre J-P Poirier E Humler and A W Hofmann ldquoThechemical composition of the EarthrdquoEarth and Planetary ScienceLetters vol 134 no 3-4 pp 515ndash526 1995

[19] S R Hart and A Zindler ldquoIn search of a bulk-Earth composi-tionrdquo Chemical Geology vol 57 no 3-4 pp 247ndash267 1986

[20] R Arevalo JrW FMcDonough andM Luong ldquoTheKU ratioof the silicate Earth insights intomantle composition structureand thermal evolutionrdquo Earth and Planetary Science Letters vol278 no 3-4 pp 361ndash369 2009

[21] H Palme and H S C OrsquoNeill ldquoCosmochemical estimates ofmantle compositionrdquo in The Mantle and Core R W CarlsonEd vol 2 ofTreatise of Geochemistry pp 1ndash38 Elsevier OxfordUK 2003

[22] M Javoy E Kaminski F Guyot et al ldquoThe chemical com-position of the Earth enstatite chondrite modelsrdquo Earth andPlanetary Science Letters vol 293 no 3-4 pp 259ndash268 2010

[23] H S C OrsquoNeill andH Palme ldquoCollisional erosion and the non-chondritic composition of the terrestrial planetsrdquo PhilosophicalTransactions of the Royal Society A vol 366 no 1883 pp 4205ndash4238 2008

[24] J H Davies and D R Davies ldquoEarthrsquos surface heat fluxrdquo SolidEarth vol 1 no 1 pp 5ndash24 2010

[25] C Jaupart S Labrosse and J C Mareschal ldquoTemperaturesheat and energy in the mantle of the Earthrdquo in Treatise ofGeophysics D J Stevenson Ed pp 1ndash53 Elsevier AmsterdamThe Netherlands 2007

[26] G L Fogli E Lisi A Palazzo and A M Rotunno ldquoCombinedanalysis of KamLAND and Borexino neutrino signals from Thand U decays in the Earthrsquos interiorrdquo Physical Review D vol 82no 9 Article ID 093006 9 pages 2010

[27] L M Krauss S L Glashow and D N Schramm ldquoAntineutrinoastronomy and geophysicsrdquo Nature vol 310 no 5974 pp 191ndash198 1984

[28] C G Rothschild M C Chen and F P Calaprice ldquoAntineu-trino geophysics with liquid scintillator detectorsrdquo GeophysicalResearch Letters vol 25 no 7 pp 1083ndash1086 1998

[29] S Enomoto E Ohtani K Inoue and A Suzuki ldquoNeutrinogeophysics with KamLAND and future prospectsrdquo Earth andPlanetary Science Letters vol 258 no 1-2 pp 147ndash159 2007

[30] G L Fogli E Lisi A Palazzo and A M Rotunno ldquoGeo-neutrinos a systematic approach to uncertainties and correla-tionsrdquo Earth Moon and Planets vol 99 no 1ndash4 pp 111ndash1302006

[31] F Mantovani L Carmignani G Fiorentini and M LissialdquoAntineutrinos fromEarth a referencemodel and its uncertain-tiesrdquoPhysical ReviewD vol 69 no 1 Article ID 013001 12 pages2004

[32] G Fiorentini G L Fogli E Lisi F Mantovani and A MRotunno ldquoMantle geo-neutrinos in KamLAND and BorexinordquoPhysical Review D vol 86 Article ID 033004 11 pages 2012

[33] M Coltorti R Boraso F Mantovani et al ldquoU and Th contentin the central apennines continental crust a contribution to thedetermination of the geo-neutrinos flux at LNGSrdquo Geochimicaet Cosmochimica Acta vol 75 no 9 pp 2271ndash2294 2011

[34] G Fiorentini M Lissia F Mantovani and R Vannucci ldquoHowmuch uranium is in the Earth Predictions for geoneutrinos atKamLANDrdquo Physical Review D vol 72 no 3 Article ID 03301711 pages 2005

[35] W MWhite and E M Klein ldquoThe oceanic crustrdquo inThe CrustR L Rudnick Ed vol 3 of Treatise on Geochemistry ElsevierOxford UK 2003

[36] R Arevalo Jr and W F McDonough ldquoChemical variations andregional diversity observed in MORBrdquo Chemical Geology vol271 no 1-2 pp 70ndash85 2010

[37] V J M Salters and A Stracke ldquoComposition of the depletedmantlerdquo Geochemistry Geophysics Geosystems vol 5 no 5Article ID Q05004 2004

[38] R K Workman and S R Hart ldquoMajor and trace elementcomposition of the depletedMORBmantle (DMM)rdquo Earth andPlanetary Science Letters vol 231 no 1-2 pp 53ndash72 2005

[39] F Mantovani ldquoGeo-neutrinos phenomenology and experi-mental prospectsrdquo in Proceedings of the AAP11 ConferenceWien Austria 2011

[40] F Mantovani ldquoGeo-neutrinos combined KamLAND andBorexino analysis and futurerdquo in Proceedings of the NeutrinoGeoscience Conference Takayama Japan 2013


[41] KamLAND Collaboration ldquoKamLAND a liquid scintillatoranti-neutrino detector at the Kamioka siterdquo Proposal for USinvolvement STANFORD-HEP-98-03 RCNS-98-15 1998

[42] B E Berger J Busenitz T Classen et al ldquoThe KamLAND full-volume calibration systemrdquo Journal of Instrumentation vol 4Article ID P04017 30 pages 2009

[43] GAlimonti C Arpesella H Back et al ldquoTheBorexino detectorat the laboratori nazionali del Gran Sassordquo Nuclear Instrumentsand Methods in Physics Research A vol 600 no 3 pp 568ndash5932009

[44] G Alimonti C Arpesella M B Avanzini et al ldquoThe liquidhandling systems for the Borexino solar neutrino detectorrdquoNuclear Instruments andMethods in Physics ResearchA vol 609no 1 pp 58ndash78 2009

[45] H Back G Bellini J Benziger et al ldquoBorexino calibrationshardwaremethods and resultsrdquo Journal of Instrumentation vol7 no 10 Article ID 10018 36 pages 2012

[46] K Eguchi S Enomoto K Furuno et al ldquoFirst results fromKamLAND evidence for reactor antineutrino disappearancerdquoPhysical Review Letters vol 90 no 2 Article ID 021802 6 pages2003

[47] T Araki K Eguchi S Enomoto et al ldquoMeasurement ofneutrino oscillation with KamLAND evidence of spectraldistortionrdquo Physical Review Letters vol 94 Article ID 0818015 pages 2005

[48] S Abe T Ebihara S Enomoto et al ldquoPrecision measurementof neutrino oscillation parameters with KamLANDrdquo PhysicalReview Letters vol 100 no 22 Article ID 221803 5 pages 2008

[49] T Araki S Enomoto K Furuno et al ldquoExperimental investiga-tion of geologically produced antineutrinos with KamLANDrdquoNature vol 436 no 7050 pp 499ndash503 2005

[50] A Gando Y Gando K Ichimura et al ldquoPartial radiogenicheat model for Earth revealed by geo-neutrino measurementsrdquoNature Geoscience vol 4 pp 647ndash651 2011

[51] A Gando Y Gando H Hanakago et al ldquoReactor on-offantineutrino measurement with KamLANDrdquo Physical ReviewD vol 88 no 3 Article ID 033001 10 pages 2013

[52] A Gando Y Gando H Hanakago et al ldquoMeasurement ofthe double-120573 decay half-life of 136Xe with the KamLAND-ZenexperimentrdquoPhysical ReviewC vol 85 no 4 Article ID 0455046 pages 2012

[53] G Alimonti G Anghloher C Arpesella et al ldquoUltra-lowbackground measurements in a large volume undergrounddetector Borexino collaborationrdquo Astroparticle Physics vol 8no 3 pp 141ndash157 1998

[54] G Alimonti C Arpesella G Bacchiocchi et al ldquoA large-scalelow-background liquid scintillation detector the counting testfacility at Gran Sassordquo Nuclear Instruments and Methods inPhysics Research A vol 406 no 3 pp 411ndash426 1998

[55] C Arpesella G Bellini J Benziger et al ldquoFirst real timedetection of 7Be solar neutrinos by Borexinordquo Physics LettersSection B vol 658 no 4 pp 101ndash108 2008

[56] C Arpesella H O Back M Balata et al ldquoDirect measurementof the 7Be solar neutrino flux with 192 days of borexino datardquoPhysical Review Letters vol 101 Article ID 091302 6 pages2008

[57] G Bellini J Benziger D Bick et al ldquoPrecision measurementof the 7Be solar neutrino interaction rate in Borexinordquo PhysicalReview Letters vol 107 no 14 Article ID 141302 5 pages 2011

[58] G Bellini J Benziger D Bick et al ldquoAbsence of a day-nightasymmetry in the 7Be solar neutrino rate in Borexinordquo PhysicsLetters B vol 707 no 1 pp 22ndash26 2012

[59] G Bellini J Benziger D Bick et al ldquoFirst evidence of pepsolar neutrinos by direct detection in BorexinordquoPhysical ReviewLetters vol 108 no 5 Article ID 051302 6 pages 2012

[60] G Bellini J Benziger S Bonetti et al ldquoMeasurement of thesolar 8B neutrino rate with a liquid scintillator target and 3MeVenergy threshold in the Borexino detectorrdquo Physical Review Dvol 82 no 3 Article ID 033006 10 pages 2010

[61] G Bellini J Benziger S Bonetti et al ldquoObservation of geo-neutrinosrdquo Physics Letters B vol 687 no 4-5 pp 299ndash304 2010

[62] G Bellini J Benziger D Bick et al ldquoMeasurement of geo-neutrinos from 1353 days of Borexinordquo Physics Letters B vol722 no 4-5 pp 295ndash300 2013

[63] G Bellini D Bick G Bonfini et al ldquoSOX short distanceneutrino Oscillations with Borexinordquo Journal of High EnergyPhysics vol 2013 article 38 2013

[64] B Ricci V Chubakov J Esposito et al ldquoReactor antineutrinossignal all over the worldrdquo in Proceedings of the NeuTel Confer-ence Venice Italy 2013

[65] T A Mueller D Lhuillier M Fallot et al ldquoImproved predic-tions of reactor antineutrino spectrardquo Physical Review C vol83 no 5 Article ID 054615 17 pages 2011

[66] P Huber ldquoDetermination of antineutrino spectra from nuclearreactorsrdquo Physical Review C vol 84 Article ID 024617 16 pages2011

[67] GMentionM Fechner T Lasserre et al ldquoReactor antineutrinoanomalyrdquo Physical ReviewD vol 83 no 7 Article ID 073006 20pages 2011

[68] J W Crowley ldquoMantle convection and heat lossrdquo in Proceedingsof the Neutrino Geoscience Conference Takayama Japan 2013

[69] M C Chen ldquoGeo-neutrinos in SNO+rdquo Earth Moon andPlanets vol 99 no 1ndash4 pp 221ndash228 2006

[70] M Chen ldquoSNO+rdquo in Proceedings of the Neutrino GeoscienceConference Takayama Japan 2013

[71] Z Wang ldquoUpdate of DayaBay II Jiangmen anti-neutrino obser-vation spectrometerrdquo in Proceedings of the Neutrino GeoscienceConference Takayama Japan 2013

[72] M Wurm J F Beacom L B Bezrukov et al ldquoThe next-generation liquidscintillator neutrino observatory LENArdquoAstroparticle Physics vol 35 no 11 pp 685ndash732 2012

[73] J G Learned S T Dye and S Pakvasa ldquoHanohano a deepocean anti-neutrino detector for unique neutrino physics andgeophysics studiesrdquo 2008 httparxivorgabs08104975

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


FluidsJournal of

Atomic and Molecular Physics

Journal of



Advances in Condensed Matter Physics

OpticsInternational Journal of



AstronomyAdvances in

International Journal of


Superconductivity


Statistical MechanicsInternational Journal of


GravityJournal of


AstrophysicsJournal of


Physics Research International


Solid State PhysicsJournal of

Computational Methods in Physics

Journal of



Soft MatterJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


Journal of

Biophysics


ThermodynamicsJournal of


results and their geological implications Finally in Section 7we describe the future perspectives of the field of neutrinogeoscience and the projects having geoneutrino measure-ment among their scientific goals

2 Geoneutrinos

Today the Earthrsquos radiogenic heat is in almost 99 producedalong with the radioactive decays in the chains of 232Th(12059112

= 140 sdot 109 year) 238U (120591

12= 447 sdot 10

9 year)235U (120591

12= 070 sdot 10

9 year) and those of the 40K isotope(12059112

= 128 sdot 109 year) The overall decay schemes and the

heat released in each of these decays are summarized in thefollowing equations

238U 997888rarr206Pb+8120572 + 8119890minus + 6]

119890+ 517MeV (2)

235U 997888rarr207Pb+7120572 + 4119890minus + 4]

119890+ 464MeV (3)

232Th 997888rarr208Pb+6120572 + 4119890minus + 4]

119890+ 427MeV (4)

40K 997888rarr40Ca+119890minus + ]

119890+ 131MeV (893) (5)

40K+119890 997888rarr40Ar+]

119890+ 1505MeV (107) (6)

Since the isotopic abundance of 235U is small the overallcontribution of 238U 232Thand 40K is largely predominantIn addition a small fraction (less than 1) of the radiogenicheat is coming from the decays of 87Rb (120591

12= 481sdot10

9 year)138La (120591

12= 102sdot10

9 year) and 176Lu (12059112

= 376sdot109 year)

Neutron-rich nuclides like 238U 232Th and 235U madeup [1] by neutron capture reactions during the last stagesof massive-stars lives decay into the lighter and proton-richer nuclides by yielding 120573minus and 120572 particles see (2)ndash(4)During 120573

minus decays electron antineutrinos (]119890) are emitted

that carry away in the case of 238U and 232Th chains 8and 6 respectively of the total available energy [2] In thecomputation of the overall ]

119890energy spectrum of each decay

chain the shapes and rates of all the individual decays haveto be included detailed calculations are required to take intoaccount up to sim80 different branches for each chain [3] Themost important contributions to the geoneutrino signal arehowever those of 214Bi and 234Pa119898 in the uranium chainand 212Bi and 228Ac in the thorium chain [2]

Geoneutrino spectrum extends up to 326MeV and thecontributions originating from different elements can bedistinguished according to their different end-points thatis geoneutrinos with E gt225MeV are produced only theuranium chain as shown in Figure 1 We note that accordingto geochemical studies 232Th is more abundant than 238Uand their mass ratio in the bulk Earth is expected to be119898(232Th)119898(

238U) = 39 (see also Section 3) Because thecross-section of the detection interaction from (1) increaseswith energy the ratio of the signals expected in the detectoris 119878(232Th)119878(

238U) = 027The 40K nuclides presently contained in the Earth were

formed during an earlier and more quiet phase of themassive-stars evolution the so-called Silicon burning phase

1018

1016

1014

1012

Lum

inos

ity (s

minus1

MeV

minus1)

05 1 15 2 25 3 35 4Antineutrino energy (MeV)

238U series235U series

232Th series40K

Figure 1 The geoneutrino luminosity as a function of energy isshown for themost important reaction chains and nuclides [4] Onlygeoneutrinos of energies above the 18MeV energy (vertical dashedline) can be detected by means of the inverse beta decay on targetprotons shown in (1)

[1] In this phase at temperatures higher than 35 sdot 109 K

120572 particles protons and neutrons were ejected by photo-disintegration from the nuclei abundant in these stars andwere made available for building-up the light nuclei up toand slightly beyond the iron peak (119860 = 65) Being a lighternucleus the 40K beyond the 120573minus decay shown in (5) has alsoa sizeable decay branch (107) by electron capture see (6) Inthis case electronneutrinos are emitted but they are not easilyobservable because they are overwhelmed by themany ordersof magnitude more intense solar-neutrino fluxes Luckily theEarth is mostly shining in antineutrinos the sun converselyis producing energy by light-nuclide fusion reactions andonly neutrinos are yielded during such processes

Both the 40K and 235U geoneutrinos are below the18MeV threshold of (1) as shown in Figure 1 and thus theycannot be detected by this process However the elementalabundances ratios are much better known than the absoluteabundances Therefore by measuring the absolute content of238U and 232Th also the overall amount of 40K and 235Ucan be inferred with an improved precision

Geoneutrinos are emitted and interact as flavor statesbut they do travel as superposition of mass states and aretherefore subject to flavor oscillations

In the approximation Δ119898231sim Δ119898

2

32≫ Δ119898

2

21 the square-

mass differences of mass eigenstates 1 2 and 3 the survivalprobability 119875

119890119890for a ]

119890in vacuum is

119875119890119890= 119875 (]

119890997888rarr ]119890)

= sin412057913+ cos4120579

13(1 minus sin22120579

12sin2 (

1267Δ1198982

21119871

4119864

))

(7)



119871119900sim 120587119888ℎ

4119864

Δ1198982

21

(8)


⟨119875119890119890⟩ ≃ cos4120579

13(1 minus

1

2

sin2212057912) + sin4120579

13 (9)


119890119890sim 054



radic2119866119865119899119890 where 119899






3 The Earth









































119890energy

119878 (232Th) [TNU] = 407 sdot 120601 (

232Th)

119878 (238U) [TNU] = 128 sdot 120601 (

238U) (10)







ROC [16] 137+28

minus2373+15

minus12

Total crust 234+31

minus26250+21

minus18

CLM [16] 22+31

minus1316+22

minus10


+44

minus29354+30

minus21





















(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)




















and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





119871119900sim 120587119888ℎ

4119864

Δ1198982

21

(8)


⟨119875119890119890⟩ ≃ cos4120579

13(1 minus

1

2

sin2212057912) + sin4120579

13 (9)


119890119890sim 054



radic2119866119865119899119890 where 119899






3 The Earth









































119890energy

119878 (232Th) [TNU] = 407 sdot 120601 (

232Th)

119878 (238U) [TNU] = 128 sdot 120601 (

238U) (10)







ROC [16] 137+28

minus2373+15

minus12

Total crust 234+31

minus26250+21

minus18

CLM [16] 22+31

minus1316+22

minus10


+44

minus29354+30

minus21





















(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)




















and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics































119890energy

119878 (232Th) [TNU] = 407 sdot 120601 (

232Th)

119878 (238U) [TNU] = 128 sdot 120601 (

238U) (10)







ROC [16] 137+28

minus2373+15

minus12

Total crust 234+31

minus26250+21

minus18

CLM [16] 22+31

minus1316+22

minus10


+44

minus29354+30

minus21





















(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)




















and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics

















119890energy

119878 (232Th) [TNU] = 407 sdot 120601 (

232Th)

119878 (238U) [TNU] = 128 sdot 120601 (

238U) (10)







ROC [16] 137+28

minus2373+15

minus12

Total crust 234+31

minus26250+21

minus18

CLM [16] 22+31

minus1316+22

minus10


+44

minus29354+30

minus21





















(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)




















and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics







ROC [16] 137+28

minus2373+15

minus12

Total crust 234+31

minus26250+21

minus18

CLM [16] 22+31

minus1316+22

minus10


+44

minus29354+30

minus21





















(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)




















and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




(a)

38∘

37∘

36∘

35∘

34∘

38∘

37∘

36∘

35∘

34∘

134∘ 136∘ 138∘ 140∘ 142∘

134∘ 136∘ 138∘ 140∘ 142∘

(b)




















and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics







and tan2(12057912)


21



119890








tankRopes

InternalPMTs


Water

BufferScintillator

MuonPMTs


















119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics










119890

119864prompt = 119864]119890

minus 0784MeV (11)
















2


90

60

30

0

minus30

minus60

minus90

(TN

U)

500

400

300

200

100



















060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




060504030201

0

Rate

(eve

nts

day)

2002 2004 2006 2008 2010 2012Year



(a)

060504030201

0Obs

erve

d ra

te (e

vent

sda

y)


(b)
















Borexino KamLAND



minus27







119890fluxes from U


16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




16

14

12

10

8

6

4

2

0500 1000 1500 2000 2500 3000 3500


Borexino data



Even

ts246

pe613

tontimes

year

(a)

KamLAND data180

160

140

120

100

80

60

40

20

01 12 14 16 18 2 22 24 26

Ep (MeV)


Best-fit geo e

Even

tS02

MeV


(b)












(12)




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




S Th(T

NU

)80

60

40

20

0

SU (TNU)0 20 40 60 80

(a)

250

200

150

100

50

0

NU+N

Th


683954997

(b)


60

50

40

30

20

10

0

S geo

(TN

U)

ROC ROC

LOC LOC

Borexino KamLAND








+66

minus67) TNU (14)




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




25

2

15

1

05

0

Δ1205942



30

25

20

15

10

5

0

Man

tle si

gnal

(TN

U)



DM + EL 2DM + EL 3




30

25

20

15

10

5

0

Radi

ogen

ic h

eat f

rom

U an

dTh

(TW

)


Total sun

Total homo






Δ119871 = 746 sdot Δ119898 (238U) + 162 sdot Δ119898 (

232Th) (15)





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





















References

















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics















































































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics










































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Documents

Review Article Studying the Earth with Geoneutrinosdownloads.hindawi.com/journals/ahep/2013/425693.pdf · Advances in High Energy Physics IntheEarth,thegeoneutrinosourcesarespreadovera