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New geo neutrino results from Borexino and KamLAND

Yury Suvorov UCLA / NRC Kurchatov Inst. New geo neutrino results from Borexino and KamLAND. ( on behalf of the Borexino collaboration ) ‏. Paris 22 nd May 2013.

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New geo neutrino results from Borexino and KamLAND

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  1. Yury Suvorov UCLA / NRC Kurchatov Inst. New geo neutrino results from Borexino and KamLAND (on behalf of the Borexino collaboration)‏ Paris 22nd May 2013

  2. The measurements of the temperature gradient in the bore holes. The most recent data from Davies and Davies (2010). Over 40.000 deep bore-holes. Integrated over the Earth’s surface: 47±2 TW (~0.09 W m2 ). Bore-hole measurements Terrestrial Heat Incoming Solar radiation 340 W/m2 (~0.03 %) Sun. mWm-2 Possible geothermal heat sources: - Decay of U, Th, and 40K within the Earth; - Primordial energy of the planetary accretion; - Latent heat from the phase transitions; Paris 22nd May 2013

  3. According to seismological measurements of the propagation speed of the P-type (pressure) and S-type (travers) waves the Earth is divided into several layers. Density but not the composition. Earth Structure Crust (0.4% of Mearth), Mantle (68% of Mearth), Core (32% of Mearth) Preliminary Reference Earth Model (PREM) Dziewonski, Anderson (1981) Paris 22nd May 2013

  4. The Bulk Silicate Earth model (BSE). Earth Chemical Composition “Primitive Mantle” composition before the crust differentiation, but after the metal core separation. 1) Petrologic studies: terrestrial samples and lab. analysis; 2) Cosmological constraints: meteorites samples composition (chondritic meteorites) with respect to the solar photosphere; 3) Seismic profile of the Earth (density). G. Fiorentini et al., Phys. Rev. D 86 (2012) 033004. Crust Present Mantle Primitive Mantle (differentiation) Paris 22nd May 2013

  5. Emax(U) = 3.26 MeV Emax(Th) = 2.25MeV Emax(K) = 1.3 MeV Released in the decay chains heat, antineutrino flux and the mass of the U, Th and K are stricrly connected. Radiogenic Heat and Neutrinos Luminosity [1024 s-1] = 7.64 m(U) + 1.62m(Th) + 27.10·10-4 m(K) Radiogenic Heat [TW] = 9.85· m(U) + 2.67· m(Th) + 3.33· m(K) 238U→206Pb + 8α+ 6e + 6 anti-ν +51.7MeV 232Th→ 208Pb +6α+ 4e + 4 anti-ν +42.7MeV 40K→ 40Ca+ 1e + 1 anti-ν + 1.311MeV (89%) Radiogenic Heat from PM models: 1) Crust: ~7 TW 2) Mantle: (1-19) TW (various BSE models) 3) Core: 0 TW Paris 22nd May 2013

  6. Historical introduction Gamov in the letter to Reines (1953): Dear Fred, ...your background neutrinos may just be coming from high energy βdecaying members of U and Th families in the crust of the Earth. G. Marx, N. MenyardMitteilungenderSternwarte, Budapest, 48 (1960): Firstestimationoftheanti-neutrinofluxesfromU,ThandK. М.А.Мarkov “Нейтрино”, М., Nauka (1964): First proposal to use the reaction of inverse βdecay for the geo-nu registration. GernotEderNuclPhys 78 (1966) Terrestrialneutrinos: Ideatodeterminethe abundanceofsomeelementsbythestudyofthegeoneutrinos. Paris 22nd May 2013

  7. KamLAND 2005-2011 2005 – “Experimental investigation of geologically produced anti-neutrinos” Nature 436, 499-503 (28 July 2005)‏ “Assuming a Th/U mass concentration ratio of 3.9, the 90 % C.L. for the total number of geoneutrinos detected is 4.5 to 54.2.” 2008 - new results based on the greater statistics yield 73±27 ev (~ 2.5σ C.L.)‏ “The indication of an excess of low-energy anti-neutrinos consistent with an interpretation as geo-neutrinos persists.”Phys. Rev. Lett. 100 (2008) 221803 2011 - new results: ~6 yr of data, 106 +29-28 ev. Null hypothesis is rejected at 99.997 % C.L. :‏Nature Geoscience 4 (2011) 647 Paris 22nd May 2013

  8. Borexino 2010 events events First“Observation of the Geo-Neutrinos”. (Physics Letters B Volume 687, Issues 4-5, 19 April 2010, Pages 299-304) Absence of the geo-ν signal is rejected at 99.997% C.L. Paris 22nd May 2013

  9. Neutrino Geoscience Japan, March 2013 New Borexino results http://arxiv.org/abs/1303.2571 New KamLAND results http://arxiv.org/abs/1303.4667 http://www.awa.tohoku.ac.jp/geoscience2013/ Paris 22nd May 2013

  10. Modeling of GeoNu signal In order to extract the Geo neutrino signal (S) for U and Th for the given site on the Earth’s surface the three components has to be considered: SExpected= SLOCal + SRestOf Crust + SMantle SMantle = SBSE – (SLOC + SROC) Borexino LOCal crust (~500 x 500 km): - Detailed geophysical model of the local crust; - Main tectonic structures; - Direct and detailed survey of U and Th content; - Hierarchy of uncertainties sources; KamLAND Rest Of Crust: - Discrimination of OC and CC; - Thickness and extension of the main continental reservoirs; - U and Th abundance of the crustal layers; - Evaluation of the uncertainties; G. Fiorentini et al., Phys. Rev. D 86 (2012) 033004 Special thanks to Fabio Mantovani Paris 22nd May 2013

  11. 1) LOC: The detailed study of the Borexino site M.Coltorti et al, Geochimica et Cosmochimica Acta 75, 2271 (2011); 2) ROC: (2o x 2o) tiles geological map “CRUST 2.0” + Y. Huang et al., arXiv:1301.0365; 3) Mantle = BSE – Crust (Low and High cases). Expected signal in Borexino Based on G. Fiorentini et al., Phys. Rev. D 86 (2012) 033004. Expected in Borexino rate is: ~10 ev/yr/ LS mass 278ton 1 TNU = 1 ev in 1032 protons / yr Paris 22nd May 2013

  12. 1) LOC: refined local model for Kamioca -Mantovani et al. Phys. Rev. D 69 2004 - hep-ph/0309013, G. Fiorentini et al., Phys. Rev. D 86 (2012) 033004. 2) ROC: (2o x 2o) tiles geological map “CRUST 2.0” + Y. Huang et al., arXiv:1301.0365. 3) Mantle (BSE – Crust; Low and High cases). Expected signal in KamLAND Paris 22nd May 2013

  13. Expected Geo-signals in BX & KL Thanks to Fabio Mantovani, see his talk @ http://www.awa.tohoku.ac.jp/geoscience2013/?page_id=269 Paris 22nd May 2013

  14. Borexino & KamLAND ~3600 m.w.e. (Φµ = 1.2 µ/m2/hr); - Mean distance from reactor: ~1170km; - 13m S.S. Sphere, 2212 8” PMTs; - 8.5m Nylon Inner Vessel; - 278 tons of LS: (PC @ 1.5g/l PPO); - 18m S.S.Water Tank, 2.4kt of HP H2O; - Muon veto: 208 8” PMTs: - Energy Resolution: 5%/√E(MeV) ; - Vertex resolution: 11cm/√E(MeV). - Exposure: (3.69±0.16)x1031 proton x yr; ~2700 m.w.e. (Φµ = 5.4 µ/m2/hr); - Mean distance from reactor: ~180km; - 18m S.S. Sphere, 1325 17”+554 20” PMTs; - 13m Nylon Inner Baloon; - 1kt of LS: (80%dodecan + 20%PC)@1.36g/l PPO; - 18m S.S.Water Tank, 3.2kt of HP H2O; - Muon veto: 225 20” PMTs: - Energy Resolution: 6.4%/√E(MeV); - Vertex resolution: 12cm/√E(MeV). - Exposure: (4.9±0.1)x1032 proton x yr; Paris 22nd May 2013

  15. Geo neutrino analysisin Borexino Paris 22nd May 2013

  16. Reactor anti-ν's in Borexino In this study (2007-2012) were considered the overall of 446 cores worldwide! Main contribution from ~194 European nuclear plants. 3 most powerful power plants in France give13% of the total signal. ~245 plants from the rest of the world give 2.5 %. Contribution from the spent fuel 1%. Weighted mean-base line: ~1170km Knowledge of the exact duty cycle and the fuel composition of the nuclear plants is of the crucial importance! Nominal thermal power and monthly load factors for each plant (World Wide) from the IAEA and EDF. Paris 22nd May 2013

  17. The diff. reactor anti-ν spectrum Reactor anti-ν spectrum in Borexino Expected in Borexino In the whole spectrum: W oscill. : (33.3±2.4) ev in (613±26) ton x yrWO oscill. : (60.4±4.1) ev in (613±26) ton x yr Sys. errors on the expected signal Sum U235 Pu239 U238 Pu241 Paris 22nd May 2013

  18. Geo-ν signal in Borexino Emax(U) = 3.26 MeV Emax(Th) = 2.25MeV Emax(K) = 1.3 MeV Expected in Borexino signal from the geo-ν's: Ideal expected spectrum MC with energy response of the detector. ~10 ev/yr in 278tons Paris 22nd May 2013

  19. Candidates selection The 1352.6 live days (Dec. 2007 - Aug. 2012) 1)Qprompt > 408 p.e.(reaction threshold); 2)860 p.e. < Qdelayed <1300 p.e.(2.2 MeV gamma, AmBe data) 3)∆R< 1m(MC simulations); 4)20µs < ∆t < 1280µs( 5 tau of neutron, AmBe source data t = (254.5±1.8)μs ); 5)RIV – Rprompt > 0.25m (weekly reconstruction of the Vessel shape based on data); 6)Gdelayed < 0.015 (Pulse Shape Analysis of AmBe source data). Total detection efficiency determined with MC is 0.84±0.01 Paris 22nd May 2013

  20. Borexino background The fiducial exposure after all cuts is (613 ± 26) ton × yr Expected signal from geo+reactors: ~10 ev + ~33 ev Paris 22nd May 2013

  21. Selected candidates After all cuts, in 1198.9 d we select 46 candidates. Paris 22nd May 2013

  22. Unbinned maximal likelihood analysis Ingredients for the fit: Free: Ngeo , Nreac ; Constrained (±1σ): LiHe , (α,n), accidentals. Signal/Background ~ 65:1 Paris 22nd May 2013

  23. “Geo vs Reactors” In terms of signal: Sgeo = (38.8±12.0) TNU Sreac = (84.5-16.9+19.3) TNU 3σ 2σ The null hypothesis (Sgeo= 0) is rejected at 99.9994 % C.L. (4.5σ) 1σ (high) (low) Full agreement with the expectation on the reactor anti neutrinos (33.3±2.4) ev in the presence of neutrino oscillations. Paris 22nd May 2013

  24. Geo neutrino analysisin KamLAND Paris 22nd May 2013

  25. Three periods 3 months of shut down Period 1: 2002-2007 with 1486d Period 2: 2007-2011 with 1154d Period 3: 2011-2012 with 351d Paris 22nd May 2013

  26. Candidates selection & bkg 2991 live days (Mar. 2002 - Nov. 2012) 1)0.9 MeV < Qp < 8.5 MeV ; 2)1.8(4.4) MeV < Qd <2.6 (5.6) MeV (H/C); 3)∆R< 2m ; 4)0.5µs < ∆t < 1000µs; 5)Rp, Rd < 6.0m; (Period 3: Rd > 2.5m & ρd>2.5m & Zd>0m); The fiducial exposure is (4.9±0.1)x1032 proton x yr Total number of the reactor anti-nu expected: 1963.76 ev Paris 22nd May 2013

  27. KamLAND Geo neutrinos The best fit results: SUgeo = 116 ev SThgeo = 8 ev In the assumption U/Th = 3.9: Sgeo = 116-27+28 [ev] Sgeo = 31.1±7.3 [TNU] SExpectedgeo = 35.4±2.5 [TNU] The null hypothesis (Sgeo= 0) is rejected at 99.9998 % C.L. Paris 22nd May 2013

  28. New Results Impact Paris 22nd May 2013

  29. Geo-ν signal vs BSEs +1σ SBXgeo = (38.8±12.0) TNU SKLgeo = (31.1±7.3) TNU BX best value -1σ KL best value The models differ by the contribution from the present mantle. Based on G. Fiorentini et al., Phys. Rev. D 86 (2012) 033004. Both experiments are in agreement with available BSE models. Paris 22nd May 2013

  30. Earth radiogenic power Correlation between Sgeo(U+Th) and Hgeo(U+Th) is not straightforward. Sgeo (Crust)= (23.4±2.8) TNU Sgeo (Crust)= (25±2) TNU Borexino KamLAND Preliminary Thanks to Fabio (Crust) 3.3 yr, (3.69±0.16)x1031prot x yr Sgeo = (38.8±12.0) TNU 8.2 yr, (4.9±0.1)x1032prot x y Sgeo = (31.1±7.3) TNU Heat (BX) = (23±14)TW Heat (KL) = (13±9)TW Preliminary Paris 22nd May 2013

  31. Signal from the Mantle N(geo) = N (Crust) + N (Mantle) Borexino : S BXgeo (Total)= (38.8±12.0) TNU S BXgeo (Crust)= (23.4±2.8) TNU SBXgeo (Mantle) = (15.4±12.3) TNU KamLAND: S KLgeo (Total)= (31.1±7.3) TNU S KLgeo (Crust)= (25±2) TNU SKLgeo (Mantle) = (6.1±7.6) TNU Paris 22nd May 2013

  32. Th/U ratio (Borexino) Unbinned Lkl analysis. Two independent PDFs for U and Th contributions. Best fit values are : NTh=(3.9±4.7)ev and NU=(9.8±7.2)ev In terms of signal: STh=(10.6±12.7)TNU and SU=(26.5±19.5)TNU Th/U = 3.9 First attempt of the spectroscopic measurement of U & Th. The best value of the Th/U ratio is in a good agreement with the chondritic value. Paris 22nd May 2013

  33. Summary For the first time the same level of compatibility is observed at two different sites: Gran Sasso in Italy and Kamioka in Japan. SBXgeo = (38.8±12.0) TNU. Null hypothesis is rejected at 99.9994 C.L. SKLgeo = (31.1±7.3) TNU. Null hypothesis is rejected at 99.9998 C.L. The obtained results are consistent with available BSE models. First extraction of the Mantle Signal: SBX(Mantle) = (15.4±12.3) TNU and SKL (Mantle) = (6.1±7.6) TNU (Borexino + KamLAND 2011 = (14.1±8.1) TNU) First attempt of the Spectroscopic Measurement of U and Th. The obtained in Borexino best value for the Th/U is close to the chondritic one. What’s next? Neutrino tomography of the Earth interior, 10th kt scale, multi-site detection: SNO+, Hanohano, LENA, Daya BayII... Paris 22nd May 2013

  34. The End

  35. BX vs KL bkg Paris 22nd May 2013

  36. Anti-ν sources Electron anti-ν from The Earth Interior Electron anti-ν from the Nuclear Power plants Paris 22nd May 2013

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