And Geo-Neutrinos
Solar and geo- neutrinos Oleg Smirnov, JINR (DLNP), Dubna
VI International Pontecorvo Neutrino Physics School August 27 - September 4, 2015, Horný Smokovec, Slovakia 1958
1960 CNO-cycle
The CNO cycle (carbon-nitrogen- oxygen) is a catalytic cycle. CNO cycle dominates in stars more massive than about 1.3 times the mass of the Sun. pp-chain reactions start occurring at temperatures around 4×106K. A self-maintaining CNO chain starts at ~15×106 K, but net result: 4 its energy output rises much more 4p → 2 He + 2e+ + 2νe + rapidly with increasing 3 γ + 26.8 MeV temperatures and at ~ 17×106 K, the CNO cycle becomes dominant. The Sun has a core temperature of around 15.7×106 K and only 1.7% of He-4 nuclei being produced in the Sun are born in the CNO cycle.
The simplest CN-cycle (CNO-I, or Bethe cycle or carbon cycle) was proposed by Hans Bethe in 1938 and, independently, in 1939 by Carl Friedrich von Weizsäcker).
Solar neutrino experiments. Chronology. Radiochemical detection of neutrinos.
- e + (A,Z) e +(A,Z+1) 35 1.2 kg of NaCl; T1/2( S)=87 d; 3 month irradiation with 1 mCi radium source-> no signal; Upper limit on capture cross section <10-30 cm2 Radiochemical detection of Solar neutrinos.
Bruno Pontecorvo, 1946: .` 37 37 - e + Cl Ar + e
V.Kuz‟min, 1965
71 71 - e + Ga Ge + e Radiochemical experiments: proposals
Target Reaction T1/2 Threshold Status MeV Chlorine 37Cl 37Ar 35.0 d 0.814 closed Gallium 71Ga 71Ge 11.4 d 0.233 running Iodine 127I 127Xe 36 d 0.789 Prototype Molybdenum 98Mo 98Tc 4·106 yr >1.74 Unsuccessful Lithium 7Li 7Be 53 d 0.862 R&D Bromine 81Br 81Xe 2·105 yr 0.470 R&D Tantalum 205Tl 205Pb 14·106 yr 0.054 R&D Ytterbium 176Yb 176Lu* 0.301 R&D (exLENS) Indium 115In 115Sn* 0.114 R&D (LENS) Homestake. Homestake Mine- mine in South Dacota.
Tank filled with 600 tones of perchloroethylene
(C2Cl4) at the depth of 1.5 km underground.
Detector was taking data from 1970 to 1994
Raymod Davis Jr. (1914-2006). Nobel prize in 2002 "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos" In 1971 Raymond Davis Jr. takes a dip in the water surrounding the perchloroethylene tank deep within the Homestake Mine. SAGE, GALLEX - GNO The main problem – the quantity of Gallium necessary to provide reasonable neutrino count was comparable with its yearly world production. In 1981 and 1985 the Gallium project was rejected in USA, NSF recommended to collaborate with Europe and USSR if the project will
1984 group headed by Till Kirsten from Max Plank In USSR works were started as early Institute presented a project of gallium experiment and as in 1975, collaboration SAGE was started to form GALLEX collaboration formed in the end of 80
Till Kirsten Vladimir Gavrin GALLEX and SAGE
Liquid metallic Ga in the window of chemical reactor of SAGE experiment Gallex/GNO Solar neutrino with Radiochemical detectors
Thres Result Target Experiment Years Reaction hold (as a fraction of SSM mass keV prediction) 1967-1995 C Cl ; [2.55 ± 0.25 SNU] Homestake 1970-1994 2 4 + 37Cl 37Ar + e- 814 615 t e 0.336 ± 0.090 108 cycles
SAGE 1990-2011: Met.Ga ; [65.1 +3.7-3.8 SNU] (operating) 211 cycles 50-57 t
71 71 - 1991-1997 e + Ga Ge + e 233 Gallex GaCl ; 0.605 ± 0.103 67 cycles 3 30.3 t 1998-2003 GNO-30 0.491 ± 0.081 58 cycles Gallex+GNO 0.541 ± 0.081 [67.6± 5.1 SNU] Gallex+GNO+SAGE [66.1 ± 3.1 SNU]
Cl : pp( 0%) + 7Be(13%) + pep(2.7%) + CNO(2.4%) + 8B(82%) Ga: pp(55%) + 7Be(28%) + pep(2.3%) + CNO(3.4%) + 8B(11%) Real time detectors
The first one was water Cherenkov detector KamiokaNDE-II started in 1988 in Japan (at the 1000 m depth in the Kamioka mine).
+ e- + e-
• SuperKamiokande (or Super-K) — updated (scaled) version of Kamiokande-II, located 180 miles to the north from Tokyo. Japan-USA collaboration. Construction ended in1996. • 50 ktones of higly purified water. • 11146 PMTs Some pictures
Future Nobel prize winner is happy to see new PMT with large area photocathode, specially designed by Hamamatsu photonics Neutrino detection in Neutrinogram of the Sun (angle SuperKamiokande. Points – coordinates), obtained during first 500 PMTs, light ring – Cherenkov days of the data taking by SuperK. light from relativistic recoil Intensity of color corresponds to the electrons. number of detected neutrinos in corresponding direction. KamiokaNDE and SuperKamiokaNDE results
Target Geometric Threshold Result Detector mass coverage MeV [x106 sm-2s-1]
87-90 KamiokaNDE-II+ H20 20% 90-95 7.0 2.82+0.25 ±0.27 KamiokaNDE-III 3 kt 25% -0.24 2079 d
96-01 I 40% 5.5 2.38±0.02±0.08 1496 d Super Kamioka 02-05 II 19% 7.0 2.41±0.05+0.16 NDE 791 d -0.15 H20
50 kt (2009: life time of 2.32±0.04±0.05; reevaluated in 06-08 proton> 1034 y) III 40% 4.5 2012: 548 d 2.39 (mistake in calculations) 08-12-… IV 40% 4.0 T2K phase 1069 d
HyperKamiokaNDE ? 1 Mt 20% 4.5-7.0 Project SNO- heavy water Cherenkov detector.
Sudbury Neutrino Observatory (SNO), Ontario, Canada, at 2070 m depth.
SNO - 1000 tones of ultrapure heavy water(D2O) in ultrapure acrylic vessel , 12 m diameter. Cherenkov light is detected with 9600 PMTs, mounted at the geodesic sphere, 17 m diameter/ Detector is immersed in the ultrapure water, contained in the barrel-shaped cavern 22 m in diameter and 34 m in heights.
10 neutrino events/day Neutrino detection in heavy water Cherenkov detector - CC e + d p + p + e
• measurement of e energy • Weak directionality: 1 0 . 340 cos
NC + d p + n + x x
• Measurement of the total 8B flux
• s(e) = s(m) = s(t)
ES + e - + e - x x • Low statistics
• s(e) 6 s(m) 6 s(t) • Strong directionality:
(T = 10 MeV) e 18 e
Neutrino detection in different phases of the SNO experiment
Phase Method
I n+d: γ(single;6.25 MeV)
II (NaCl) n+35Cl: γ(multiple;8.6 MeV)
III 800 meters of 3He counters CC
NC
ES SNO results
Target, Threshold PHASE Method Result [x106 sm-2s-1] mass MeV +d p + p + e- (CC)-1.4 MeV D20 e 1.76±0.05±0.09 (CC) 99-01 +0.24 I 1006 t x+d p + n + x (NC)-2.22 MeV 5.0 2.39 -0.23 (ES) 306.4 d +0.44 - - 5.09 -0.43 (NC) x+ e x + e (ES)
01-04 1.72±0.05±0.11 (CC) +NaCl 35 36 +0.15 II 391d Cl+n Cl+8.6 MeV (2-4 γ) 5.5 2.34±0.23 -0.14 (ES) S 2t +0.28 4.81±0.19 -0.27 (NC) N O Low energy threshold analysis 5.046+0.159 +0.107 I+II 3.5 -0.152 -0.123 (LETA: 3.5 MeV) (NC)
1.67+0.05 +0.07 (CC) +3He 3He + n p + 3H + 0.76 MeV -0.04 -0.08 III +0.24 +0.09 04-06 6.0 1.77 -0.21 -0.10 (ES) counters +0.33 +0.36 5.54 -0.31 -0.34 (NC) Neutrino-2012: 8B flux (5.25±3.7%)x106 sm-2s-1 Status of MSW solution in 2002
Before SNO
April 2002 SNO
December 2002 KamLAND BOREXINO (in operation from May,2007) •278 t of liquid organic scintillator PC + PPO (1.5 g/l) • (ν,e)-scattering with low threshold (~200 keV) •Outer muon detector
13.7m 18m The original BOREX proposal was based on B-loaded scintillator (BOREX=20 x Borexino) R.S.Raghavan, S.Pakvasa, Phys. Rev. D 37, 849 - 857 (1988) "Probing the nature of the neutrino: The boron solar-neutrino experiment"
With a welter of neutrino scenarios and uncertain solar models to be unraveled, can solar-neutrino experiments really break new ground in neutrino physics? A new solar- neutrino detector BOREX, based on the nuclide 11B, promises the tools for a definitive exploration of the nature of the neutrino and the structure of the Sun. Using double-mode detection by neutrino excitation of 11B via the neutral-weak-current- and the charged- current-mediated inverse β decay in the same target, independent measurements of the total neutrino flux regardless of flavor and the survival of electron neutrinos in solar matter and a vacuum can be made. Standard models of the Sun, and almost every proposed nonstandard model of the neutrino, can be subjected to sharp and direct tests. The development of BOREX, based on B-loaded liquid-scintillation techniques, is currently in Ramaswami (Raju) S. progress. Raghavan
+ e + e E>0.25 MeV x x
11 11 + 11 + B e + C ( e + B ) e E>4 MeV
1 + e + H e + n E>1.8 MeV
10 7 n + B Li + ( 2 .3 MeV ) + ( 0 .48 MeV ) 94%
1 2 n + H H + ( 2 .2 MeV ) 6% Borexino goal, 5%
- -9 50 events/d/100t expected (νe and vμ elastic scattering on e ) or 5·10 Bq/kg (typically: drinking water ~10 Bq/kg; human body in 40K: 5 kBq) Low energy->no Cherenkov light->No directionality, no other tags-> extremely pure scintillator is needed pp-chain Borexino time table • May 2007 – May 2010: Phase I . 7Be : 5% measurement; day/night ; evidence of seasonal modulation . low threshold 8B flux; . first pep detection and best upper limit on CNO . Geo- measurement . Calibration campaign • May 2010 – October 2011: purifications • October 2011-now: Phase II • pp neutrino flux measurement • CNO neutrino flux measurement We are here now . Seasonal variations; Update of 7Be, 8B, pep (in progress); Rare processes • After CNO : calibrations campaign • 2016-2017 : SOX (search for sterile neutrinos) • Future plans : Distillation and Phase III Borexino experimental spectrum
First real-time measurement of pp- neutrino flux (~11% precision ) pp = 144 ± 13 (stat) ± 10 (syst) cpd/100 t compared to expected (MSW/LMA,HM) 131±2 cpd/100 t
pp neutrino flux:
(6.6±0.7)·1010 cm-2s-1
vs
(5.98±0.04)·1010 cm-2s-1
Zero pp count is excluded at “Neutrinos from the primary proton– 10σ level proton fusion process in the Sun” Nature, Vol. 512 (2014) pp.383-386 List of proposals on pp-neutrino search
Combining the results on pp-neutrino
• Radiochemical + 7Be Borexino: Φ(pp) = (6.14±0.61)1010 cm-2s-1 • Borexino only: Φ(pp) = (6.6±0.7)1010 cm-2s-1 • Combined Φ(pp) = (6.37±0.46)1010 cm-2s-1 (7%)
Solar neutrino fluxes and Solar luminosity Reactio Measurement cm-2s-1 MeV/1ν L n x1026 W/s pp 6.37±0.46 x1010 13.10 3.76±0.28 pep 1.6±0.3 x108 11.92 0.009±0.002 7Be 4.87±0.24 x109 12.60 0.276±0.014 8B 5.25±0.16 x106 6.63 (1.57±0.05)10-4
퐿 = 4.04 ± 0.28 ∙ 1026 W/s 26 Measured (0.4%) 퐿ʘ = 3.846 ∙ 10 W/s 90% C.L. lower limit for energy production is 3.68 ∙ 1026 W/s, i.e. we can guarantee at 90% C.L. that no more than 0.15 ∙ 1026 W/s (i.e. <4% of the total energy) is produced in reactions not cited in the table Borexino measured electron neutrino survival probability for 4 different nuclear reactions
Solar experiments vs models
Borexino Solar neutrino fluxes: theory vs experiment Reaction GS98 AGS09 cm-2s-1 Measurement Experiment pp 5.98±0.04 6.03±0.04 x1010 6.14±0.61 all Solar 6.6±0.7 BX pep 1.44±0.012 1.47±0.012 x108 1.6±0.3 BX
7Be 5.0±0.07 4.56±0.07 x109 4.87±0.24 BX 8B 5.58±0.14 4.59±0.14 x106 5.2±0.3 SNO+SK+BX+KL +0.011 5.25±0.16 -0.013 SNO LETA hep 8.0±2.4 8.3±2.5 x103 <2.3x104 90% C.L. SNO
13N 2.96±0.14 2.17±0.14 x108 Integral CNO flux 15O 2.23±0.15 1.56±0.15 X108 <7.4x108 90% C.L. BX
17F 5.52±0.17 3.40±0.16 x106
Solar CNO- neutrino cycle: a clue to the chemical composition of the Sun dominates in massive stars (~1% of solar luminosity) ―bottle-neck‖ N(p,γ) reaction, slower than expected (LUNA result).
Very sensitive to the solar abundance problem. A direct test of the heavily debated solar C, N and O abundances would come from measuring the CNO neutrinos. pep neutrinos are predicted with ~ 1% accuracy and at 1.44 MeV they could probe possible non-standard interactions in the survival probability transition region The main goal of BX-II – CNO-neutrino. Strategy: “purification by insulation”
• The key point of the analysis is the achievement of the low count of 210Po to obtain a support count rate from the parent 210Bi, which is the major residual background masking the CNO spectrum • The detector will be thermally decouple from the thermal instabilities of the experimental Hall C by covering the external wall of the Water Tank with a suitable insulating material. The purpose is to impede the convective movement triggered by the external temperature variations, letting therefore the non-intrinsic 210Po, leaving the fiducial volume only the stable intrinsic contribution in equilibrium with the parent 210Bi • With an ample period of data taking in this stable conditions the plateau value of the 210Po should be measured rather precisely, leading possibly to the sought constraint on the 210Bi and, therefore, in turn to the evaluation of the CNO through the global solar fit • If the strategy above proves not to be working a deep additional 210Bi purification will be the performed (upper limits only in this case)
210Po count in Borexino TFC
Background reduction in 11С - 91% with 51.5% live-time loss MSW with LMA parameters predicts ~3% day/night asymmetry of 8B count and no asymmetry for 7Be Borexino : no diurnal variations of 7Be neutrino flux
“negative” result on day/night assimetry with 3 years statistics (380.63 “nights” + 360.25 “days”) is in agreement with MSW/LMA predictions:
N D ADN = = 0 . 001 0 . 012 ( stat ) 0 . 007 ( syst ) N + D
G. Bellini et al., Phys. Lett. B 707 (2012). First Indication of Terrestrial Matter Effects on Solar Neutrino Oscillation
MSW prediction
SK I,II,III,IV best fit
Solar KamLAND Time variations of Solar neutrino flux
±3.5% variations due to the seasonal variation of Earth-Sun distance
SNO
• 2005: the variation at a period of one year is consistent with modulation of the neutrino flux by the Earth's orbital eccentricity. No significant sinusoidal periodicities between 1 day and 10 years. • 2009: 3 additional analyses: • 1)frequencies 1/day to 144/day, sensitivity to sinusoidal signals with amplitudes ≥12% • 2)regions in which g-mode signals (24 h - 10 min) have been claimed by experiments aboard the SoHO satellite, sensitive to signals with amplitudes of 10% or greater. • 3)extra power across the entire frequency band. • No statistically significant signal was detected in any of the three searches.
SuperK-I+SuperK-II
The SK-I and II 1-year binned solar 1.5 months bins flux data gives an agreement of Solid line: 1/r2 χ2/N.D.F. = 6/11 (52% c.l.) when compared to a straight line. Gallex+GNO
GNO/GALLEX signal vs. heliocentric 90 % CL exclusion plot in the distance of the Earth. The straight line frequency/amplitude plane from indicates the analysis of GALLEX the expected flux variation due to purely and GNO data geometrical (1/d2) effects Gallex+GNO (grouped in periods)
results are consistent with a flat behaviour; however a weak time dependency (of unknown origin) is not excluded (13.2/6 vs 10.8/5) Future projects
SNO+ 780 tons of Linear Alkyl Benzene (LAB) contained in a spherical acrylic vessel (AV) of 12 m diameter and 5 cm thickness; 9500 PMTs provides coverage of 54%. The PMTs and the AV are located in a cavity excavated in the rock filled with about 7000 tons of ultrapure water. A radon seal and Urylon liner provide a second layer of shielding to avoid any contact of the detector with the mine air. The 6000 m.w.e. rock shielding : 3 μ/hour.
LAB was chosen as scintillator for the SNO+ experiment due to its chemical compatibility with acrylic, its high light yield (50 - 100 times higher than heavy water), the good optical transparency and low scattering. Moreover, high purity levels are easily available and due to the fast decay it is possible to discriminate between beta and alpha particles. SNO+ Solar neutrino phase
7Be and 8B neutrinos pep & CNO neutrinos: U and Th < 10-17 g/g. Amongst the diffrerent daughters 210Bi is the most important since it partially falls in the region of interest. 3600 pep events/(kton·year), for electron recoils >0.8 MeV goal: ±5% total uncertainty after 3 years (including systematic and SSM) CNO measurement goal: ±10% after 3 years. KamLAND. Solar phase
LENA (Low Energy Neutrino Astronomy) 50 kt scale; ~200 p.e./MeV LS: LAB + PPO and Bis-MSB as solutes is favored
low-energy range with neutrino energies up to a few tens of MeV: Galactic Supernova neutrinos Diffuse Supernova neutrinos Geo/Reactor antineutrino Solar neutrinos
LENS • modern version of the old brilliant idea for an Indium experiment (originally proposed by R. S. Raghavan in 1976: Phys. Rev. Lett. 37 (1976) 259-262):
115 115 - 115 νe + In → Sn* + e (Ekin=Eν-114 keV)→ Sn + 2γ (tag).
• 114 keV threshold -> pp neutrino: 115In count rate: ~95 pp events/yr/ton
• Signature is inverse b correlated spatially and temporally with (e/)2 and 3 • 115In b decay rate is 250 kBq/ton
R&D results very promising in term of stability of the Indium loaded scintillator and background rejection have been recently presented.
CLEAN - Cryogenic Low Energy Astrophysics with Noble gases
pp neutrino measurement with threshold <20 keV
CLEAN detector of 9 m diameter and 100 metric ton fiducial mass, the CNO flux could be measured with a statistical uncertainty of 13 % with one year of data taking, assuming that the detector is deep enough that muon-induced backgrounds are not significant.
DEAP/CLEAN collaboration at Sadbury laboratory DEAP - Dark matter Experiment with Argon and Pulse shape discrimination
MiniCLEAN (sep.2011) Megatonne scale WC detectors
Well-proven technology of water Cherenkov detectors • HyperK (Japan) (arXiv 1109.3262) • MEMPHYS (Frejus) • LBNE-WC (US) (arXiv:1204.2295; 350 pp) Status Project Goal Medium/Mass Status
SNO+ pep/CNO 780t LS (LAB) Was planned for 2013 KamLAND-2 pep/CNO 1 kt LS After KamLAND-Zen XMASS pp (via ES) 20 kt LXe 835 kg since 2010 for ββ CLEAN pp (via ES) 50 kt LNe MiniCLEAN (500 kg) 2013 LENS pp+7Be (CC) 10 t 115In μLENS under development MOON pp+7Be (CC) 3t 100Mo R&D IPNOS pp+7Be (CC) 115In R&D HyperK,MEMPHYS, 8B Mt WC LBNE-WC LBNE,GLACIER 50-100 kt LAr LENA 50 kt LS R&D JUNO 20 kt LS R&D Geo-neutrino
Milano, October 6, 2014 Geo-neutrinos: anti-neutrinos from β-decays of radioactive elements in the Earth
238U, 232Th and 40K (87Rb,235U) release heat together with antineutrinos
•Earth emits (mainly) antineutrinos whereas Sun shines in neutrinos. • A fraction of geo-neutrinos from U and Th are above threshold for inverse b on protons: 1.8 MeV • Different components can be distinguished due to different energy spectra: e. g. anti- with highest energy are from Uranium.
Heat flow through the surface of the Earth
―Earth’s surface heat flux‖, J. H. mW m-2 Davies and D. R. Davies (2010) 47±2 TW 38 347 measurements of the thermal flux In agreement with previous estimations based on incomplete set of the same data 46±3 TW[Jaupart et al., 2007] and 44±1 TW [Pollack et al., 1993] The modern view on the age of the Earth The age of 4.54 billion years used in the present day analyses was deduced by Tera in 1980 from a careful analysis of the isotopic composition of lead in four ancient lead deposits. At present, it is known that this age corresponds either to the period of accretion of the Earth’s crust, to the period of crust formation, or to the age of the original matter from which the Earth had formed. Recent evidences argue in favour of the last variant.
Primordial heat sources: Gravitational energy Short-lived isotopes decays 26Al (7.17×105 yr) Is there any heat remaining from primordial?
Full thermal flux 47 ± 2) TW Earth’s surface heat flow 47 ± 2 TW Urey=R/Tot Mantle cooling (18 TW)
Crust R (7 ± 1 TW) (Huang et al „13) Core (~9 TW) - Mantle R (13 ± 4 TW) (4-15 TW) total R 20 ± 4 R - radiogenic heat (0.4 TW) Tidal dissipation (after McDonough & Sun ’95) Chemical differentiation after Jaupart et al 2008 Treatise of Geophysics Mapping the interior of the Earth with earthquake waves
• “seismic” follows optic laws. • P-wave (compressional) • S-wave (shear) • S-waves do not propagate in liquid (outer core) Structure of the Earth
5 principal seismic (chemical) regions: Crust (continental and oceanic) upper mantle lower mantle outer core (liquid) inner core (solid)
A: Mohorovičić discontinuity (Moho) – B: Gutenberg Discontinuity C: Lehmann–Bullen discontinuity
Chemical composition of the Earth
Albert Francis Birch (1903-1992) American geophysicist, in 1952 he published a paper in the Journal of Geophysical Research : mantle is chiefly composed of silicate minerals, the upper and lower mantle are separated by a thin transition zone, and the inner and outer core are alloys of crystalline and molten iron. • The most famous portion of the paper, however, is a humorous footnote he included in the introduction: “Unwary readers should take warning that ordinary language undergoes modification to a high-pressure form when applied to the interior of the Earth. A few examples of equivalents follow”
High Pressure Form Ordinary Meaning
Certain Dubious
Undoubtedly Perhaps
Positive proof Vague suggestion
Unanswerable argument Trivial objection
Pure iron Uncertain mixture of all the elements
Chondrites
92,3 % of stone meteorites, 85,7 % of all. chondres — spherical or elliptical inclusions (1 mm – some mm in diameter). Composition corresponds to chemical composition of the Sun, excluding light gases (H,He). It is believed that chondrites were formed directly from protoplanet matter, surrouding the Sun, by condensation with heating. No traces of melting, nondifferentiated planets
Mantle evolution
Partial crystallization Convection in mantle layers Chemical stratification
Upper mantle
Low mantle
Core
Early Earth Present Earth Bulk Silicate Earth (BSE)
• A global description of the present crust- plus-mantle system is provided by the BSE model, a reconstruction of the primordial mantle of the Earth, subsequent to the core separation and prior to crust differentiation, based on geochemical arguments. • Primitive reservoir – any region in mantle preserving this composition. Mass ratios: • M(Th)/M(U) = 3.9, • M(K)/M(U)≈104 • abundance of U - 2·10-8. chondrites - composition of primitive mantle
Used in models to put mass constraint in order to determine the abundances in the lower portion of the mantle. Impact erosion (meteorites from Mars)
Early enriched Earth crust dispersed in space, leaving depleted (non-chondritic) BSE (O’Neill and Palme, 2008) Earth models and radiogenic heat • Cosmochemiocal (based on meteorites composition) – Earth composition is based on the enstatine chindrites (E-chondrites), the only group of chindrites identical to the Earth composition (Javoy et al., 2010) : ~10 TW • Geochemical (composition on Earth minerals) – cosmochemical relative abundancies (based on carbonaceous chondrites CI) with absolute abundancies from petrology (Lyubetskaya & Korenaga,2007; McDonough & Sun, 1995; Palme & O’Neill, 2003): ~20 TW • Geophysical/geodynamical (parametric convection) – convection requires viscosity consistent with surface heat flow. Uses using scaling laws to relate heat flow and viscosity, predicting the thermal evolution of the Earth (Crowley et al., 2011; Turco, 1980): ~30 TW Compared to total 47±2 TW 9 - 36 TW are left to the internal non-radiogenic heat, definening the thermal evolution and history of the Earth. Models of the Earth and thermal flux
―Geophysical and geochemical constraints on geoneutrino fluxes from Earth's mantle‖ Ondrej Sramek et al.
Model Full thermal flux,TW Mantle contribution, TW Cosmochemical 11 ± 2 3 ±2
Geochemical 20 ± 4 12 ±4
Geophysical 33 ± 3 25 ±3
Geophysical models need relatively high contribution of radiogenic heat to explain thermal flux in the mantle (otherwise model leads to the ―thermal catastrophe‖ in archeosoic) Cosmochemical models Е-chondrites are a rare form of meteorite thought to comprise only about 2% of the chondrites that fall on Earth, and are among the most chemically reduced rocks known, with most of their iron taking the form of metal or sulfide rather than an oxide. They tend to be high in the mineral enstatite (MgSiO3), from which they derive their name. Chemically, enstatite chondrites are very low in refractory lithophile elements. Their oxygen isotopic compositions are intermediate between ordinary and carbonaceous chondrites, and are similar to rocks found on the Earth and Moon. Their lack of oxygen content may mean that they were originally formed near the center of the solar nebula that created the solar system, possibly within the orbit of Mercury. Most enstatite chondrites have experienced thermal metamorphism on the parent asteroids. Only about 200 E-Type chondrites are currently known. These meteorites were formed in the early Solar system near the young Sun and were the main building blocks of the earth group planets. Geochemical models : composition of the solar photosphere corresponds to the composition of carbonaceous chondrites (CI) CI- Ivuna, Tanzania, 1938. Rare (4.6%). The most simple meteorites. Practically no visible chondres, but contains up 20% of water and a lot of organic compounds, even aminoacids .. In the process of formation never heated above 50o C. They are chemically the most primitive known meteorites and though to be the composed of the primordial material of the Solar system. Geoneutrino – source of information on the Earth interior • The deepest mine– 12 km • Geochemical analysis is available only for the samples from the upper mantle an the crust • Seismology reconstructs the density profile but not the composition
Geoneutrino detection will provide information on the Composition of the Earth interior Open questions on the natural radioactivity in the Earth
What is the What is hidden radiogenic in the Earth‟s contribution to core? (geo- terrestrial heat reactor, 40K, production? …)?
How much U and Th in the crust?
Is the standard geochemical How much U model (BSE) and Th in the consistent with mantle? geo-neutrino data? Georeactor?
• In the core (Herndon) or on the mantle-core bound (Rusov and de Meijer) • 5-10 TW would help to explain heating, convection, He-3 anomaly, geomagnetic fiels and some other problems. • Both models are criticized by geochemists • Easy to check detecting geoneutrin Oklo
In May 1972 routine mass spectrometry of samples from the Oklo Mine showed low content of 235U (0.717% compared to normal 0.720%). Further investigations into this uranium deposit discovered uranium ore with 235U as low as 0.440%.
Oklo is the only known location for this in the world and consists of 16 sites at which self-sustaining nuclear fission reactions took place approximately 1.7 billion years ago, and ran for a few hundred thousand years, averaging 100 kW of power output .
A key factor that made the reaction possible was that, at the time the reactor went critical 1.7 billion years ago, the fissile isotope 235U made up about 3.1% of the natural uranium, which is comparable to the amount used in some of today's reactors.
Provided a check of stability for fine structure constant (α) over 2 billion years
Geo-neutrinos: anti-neutrinos from β-decays of radioactive elements in the Earth
238U, 232Th and 40K (87Rb,235U) release heat together with antineutrinos
•Earth emits (mainly) antineutrinos whereas Sun shines in neutrinos. • A fraction of geo-neutrinos from U and Th are above threshold for inverse b on protons: 1.8 MeV • Different components can be distinguished due to different energy spectra: e. g. anti- with highest energy are from Uranium.
History Gamow in letter to Reines(1953): Dear Fred, ...your background neutrinos may just be coming from high energy β decaying Members of U and Th families in the crust of the Earth.
G. Marx, N. Menyard Mitteilungen der Sternwarte, Budapest, 48 (1960) first estimation of geoneutrino fluxes from U,Th and K. M.A.Markov “Нейтрино”, М., Наука, 1964: Proposed to use inverse beta-decay reaction to detect geoneutrino
Gernot Eder Nucl Phys 78 (1966) Terrestrial neutrinos Proposed to measure abundances of radioactive elements in the Earth by studying neutrino emitted in their decays The World Wide Reference Model F. Mantovani et al. – Phys. Rev. D 69 – 2004 - hep-ph/0309013
Two detectors sensitive to geo- neutrino
Large volume LS underground detectors
Borexino: 300 t LS (3500 mwe) KamLAND: 1 kton LS (2700 mwe) Detection of geo(anti)neutrino
• Earth (in construst to the Sun) emits antineutrino. • Part of antineutrino in the U and Th decay chains is emitted with E>1.8 MeV (IBD threshold) • Contributions from U and Th are distinguishable • Oscillations are averaged:
+ + p n + e E>1.8 MeV Principal backgrounds
1)Reactor antineutrinos (81% of the total antineutrino signal in KamLAND geo-nu window [0.9-2.6 MeV] and only ~36% for the Borexino case): Geo/Reactor ratio 0.23 in KL vs 1.8 in Borexino; 2)Cosmic muons induced backgrounds, including cosmogenic production of (βn)- decaying isotopes (at LNGS the muons flux is of about factor 7 lower than at the Kamioka site) 3)Internal radioactive contamination: accidental coincidences, (αn) reactions (Borexino typical contaminations 3-4 orders of magnitude lower; KamLAND purified the LS – factor 20 on (αn) is achieved);
Reactor antineutrino Borexino 2015: antineutrino spectrum (77 events)
with chondritic Th/U ratio Th/U ratio Th/U ratio Unbinned likelihood fit using MC energy spectra for geo and the reactor antineutrinos
2 free parameters Sgeo and Sreact + backgrounds components constrained
Q = 438 p .e .( 2 ) + Q ( E 1 . 8 MeV ) ~500 p.e./MeV (electrons) vis gammas are quenched Summary of backgrounds
Source Events 9 8 +0.125 Cosmogenic Li and He 0.194 -0.089 Fast neutrons from μ in Water Tank < 0.01 (90% CL) (measured) Fast neutrons from μ in rock < 0.43 (90% CL) (MC) Non-identified muons 0.12 ± 0.01 Accidental coincidences 0.221 ± 0.004 +0.029 Time correlated background 0.035 -0.028 Spontaneous fission in PMTs 0.032 ± 0.003 (α,n) reactions in the scintillator [210Po] 0.165 ± 0.010 (α,n) reactions in the buffer [210Po] < 0.51 (90% CL) 214Bi-214Po 0.009±0.013 0.78 +0.13 TOTAL -0.10 <0.65 (combined) KamLAND-2013
+28 For Th/U=3.9 Ngeo=116 −27 6 −2 −1 Flux νe = (3.4±0.8)× 10 cm s , full antineutrino flux (all flavours): 6.2±1.5 × 106 cm−2s−1. Borexino: fit results for fixed M(Th)/M(U)=3.9 +6.5 +0.9 Ngeo=23.7 -5.7(stat) -0.6(syst) events
+11.8 +2.7 Sgeo=43.5 -10.4(stat) -2.4(syst) TNU
+8.5 +0.7 • Nreact=52.7 -7.7(stat) -0.9(syst) events +15.6 +4.9 Sreact=96.5 -14.2(stat) -5.0(syst) TNU
Predicted reactor signal 87±4 TNU
• Systematics: 4.8% on FV and 1% on the energy scale 32 • *1 TNU = 1 event on 10 protons in 1 yr (~1 kt of LS)
Sgeo:Sreact for fixed M(Th)/M(U)=3.9
-9 3.6·10 probability of Ngeo=0 (5.9 σ)
For Th/U=3.9 : +0.8 6 -2 -1 Φ(U)=(2.7 -0.7)x10 cm s +0.7 6 -2 -1 Φ(Th)=(2.3 -0.6)x10 cm s
1,3 and 5 σ contours for Sgeo:Sreact signals U/Th signal (no energy resolution)
232Th
238U Unconstrained M(U)/M(Th) fit
Th/U=3.9
1,2 and 3 σ contours for SU:STh signals Radiogenic heat: Borexino
With M(Th)/M(U)=3.9 & M(K)/M(U) = 104 the total terrestrial radiogenic power : P(U + Th + K) = +28 Geodynamical 33 -20 TW, Geochemical vs global terrestrial Cosmochemical power output
Ptot = 47±2 TW 13 TW 51 TW
Red line: ROC+LOC+1σ, homogenios mantle Blue line: ROC+LOC-1σ, radiogenic material on the mantle/core interface Radiogenic heat: KamLAND Signal from the mantle • Total contribution from the Earth crust (Coltorni et al., Huang et al.) (LOC + ROC)
is Sgeo(Crust) = (23.4 ± 2.8) TNU -> 12.75 ±1.53 events (+stat.smearing)
• subtraction of probability distributions for the total signal (from the fit) and pdf for crust (normal approximation). Non-physical values of difference are excluded and final p.d.f. renormalized to unity. Mantle could p.d.f.(Mantle)=p.d.f. (Geo)-p.d.f.(Crust) : have as little as 1-3 TW or as +15.1 much as 28 TW Sgeo(Mantle) = 20.9 -10.3 TNU
with a probability of 98% we observe at least 1 event from the mantle
• Note:
– Mean value is bigger compared to a simple difference
Study of the local geology LNGS (Coltorti et al., Geo.Cosm. Acta 75(2011) 2271) Distances R< 900 km gives ~50% of the signal.
U and Th content in samples
Using available seismical and stratigraphical data (relative geological age of sediments) 3D model has been constructed (down to Moho depth) for 106 cells with 1 km3 volume
Contribution from the local crust
Sgeo(LOC) = (9.7±1.3) TNU.
1 TNU = 1 event per 1032 target nuclei in 1 yr Geo-neutrino measurements with KamLAND
Year Live Exposure Ncand Ngeo Sgeo TNU P(0) time, p·yr [0.9-2.6] ×106 cm-2s-1 days MeV +19 +3.9 -2 749.1 (7.09±0.35) 152 25 -18 5.1 -3.6 4.6·10 2005 ×1031 2008 1486 2.44×1032 73±27 4.4±1.6 4.5·10-3
+29 +1.2 -5 2011 2135 (3.49±0.07) 841 106 -28 4.3 -1.1 3·10 ×1032 (4.2σ)
+28 -6 2013 2991 (4.90±0.10) 116 -27 3.4±0.8 2·10 ×1032 2005) Araki T., et al., Nature 436 (2005) 499. 2008) Araki T., et al., Phys. Rev. Lett. 100 (2008) 221803. 2011) Gando A., et al., Nature Geoscience 4 (2011) P.647--651. 2013) Gando A., et al., Phys. Rev. D 88 (2013) 033001 Geo-neutrino measurements with Borexino
Year Live Exposure t·yr Ncand Ngeo Sgeo TNU P(0) time, days +4.1 +27.0 -5 537.2 252.6 21 9.9 -3.4 65.2 -22.4 3·10 2010 (+41%;-34%) (4.2σ)
2013 1363 613 + 26 46 14.3±4.4 38.8±12.0 6·10-6 (31%) (4.9σ) +6.5 +12.1 -9 2015 2056 907±44 77 23.7 -5.7 43.5 -10.7 3.6·10 (+28%;-25%) (5.9σ)
2010)G. Bellini et al., Phys. Lett. B 687 (2010) 299 2013)G. Bellini et al., Phys. Lett. B 722 (2013) 295 2015)M. Agostini et al., Phys. Rev. D 92, 031101 (2015) In current approach Borexino needs another 17 years to achieve 100 events statistics for geo-neutrino Comparison with models
2015 2013
x-axis : total U mass in corresponding BSE modelполная масса урана, Red upper - ―maximal‖ models : max. possible amount of radiogenic material, uniformly distributed in the mantle (+1σ). Blue lower -―minimal‖ models : min.possible amount of radiogenic material in thin layer at the bottom of the mantle (-1σ). Summary of results on the geoneutrino measurements
Georeactor power is limited by experiments
• Borexino • <4.5 TW (95% C.L.) • KamLAND: • <3.1 TW (90% C.L.) or <3.7 (95% C.L.) Upcoming experiment: SNO+
29 geo-neutrino events per live- year (in 780 tones LAB) compared with 26 events from reactors in the same energy range
Local Geology around Sudbury maybe the best understood portion of crust in the world JUNO (20 kt LS)
JUNO (20 kt LS)
10% in 100 days Large Scale Projects
LENA: 50 kton Hanohano: 10 kton Extracting mantle contribution is very important from the geophysical point of view. The combination of data from multiple sites and data from an oceanic experiment would provide valuable information.
~1500 geonu events/yr ~100 geonu events/yr Conclusions
• 1)Geoneutrino existence is confirmed independently by Borexino and KamLAND; • 2)The precision of both available measurements (Borexino and KL) is still too low: ~25% for R(U+Th) signal, and much worse for the unconstrained R(U) and R(Th) measurements • 3)Different geological models for the moment can’t be discriminated by existing measurements, more precise measurements are needed; • 4)Regional measurements in location of experiments are needed to provide more precision for the models; • 5)Independent measurements at various sites are highly desirable to check contributions from crust/mantle; • 6)We are expecting more input for the geological models from future detectors .