New geo neutrino results from Borexino and Kam
New geo neutrino results from Borexino and Kam. LAND Yury Suvorov UCLA / NRC Kurchatov Inst. (on behalf of the Borexino collaboration) Paris 22 nd May 2013
Terrestrial Heat Bore-hole measurements 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 m 2 ). Incoming Solar radiation 340 W/m 2 (~0. 03 %) Sun. Global heat loss [TW] m. Wm-2 Possible geothermal heat sources: - Decay of U, Th, and 40 K within the Earth; Primordial energy of the planetary accretion; - Latent heat from the phase transitions; Williams and von Herzen [1974] 43 Davies [1980] 41 Sclater et al. [1980] 42 Pollack et al. [1993] 44 ± 1 Hofmeister et al. [2005] 31 ± 1 Jaupart et al. [2007] * 46 ± 3 Davies and Davies [2010] 47 ± 2 Paris 22 nd May 2013
Earth Structure 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. Crust (0. 4% of Mearth), Mantle (68% of Mearth), Core (32% of Mearth) Preliminary Reference Earth Model (PREM) Dziewonski, Anderson Paris 22 nd May 2013 (1981)
Earth Chemical Composition The Bulk Silicate Earth model “Primitive Mantle” composition(BSE). 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). Primitive Mantle (differentiation) G. Fiorentini et al. , Phys. Rev. D 86 (2012) 0 Crust Present Mantle Paris 22 nd May 2013
Radiogenic Heat and Neutrinos Released in the decay chains heat, antineutrino flux and the mass of the U, Th and K are stricrly connected. 238 U→ 206 Pb + 8α+ 6 e + 6 anti-ν +51. 7 Me. V 232 Th→ 208 Pb +6α+ 4 e + 4 anti-ν +42. 7 Me. V 40 K→ 40 Ca+ 1 e + 1 anti-ν + 1. 311 Me. V (89%) Emax(U) = 3. 26 Me. V Emax(Th) = 2. 25 Me. V Emax(K) = 1. 3 Me. V Luminosity [1024 s-1] = 7. 64 m(U) + 1. 62 m(Th) + 27. 10· 10 -4 m(K) Radiogenic Heat [TW] = 9. 85· m(U) + 2. 67· m(Th) + 3. 33· m(K) Radiogenic Heat from PM models: 1) Crust: ~7 TW 2) Mantle: (1 -19) TW (various BSE models) 3) Core: 0 TW Paris 22 nd May 2013
Historical introduction Gamov in the 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 the anti-neutrino fluxes from U, Th and K. М. А. Мarkov “Нейтрино”, М. , Nauka (1964): First proposal to use the reaction of inverse β decay for the geo-nu registration. Gernot Eder Nucl Phys 78 (1966) Terrestrial neutrinos: Idea to determine the abundance of some elements by the study of the geoneutrinos. Paris 22 nd May 2013
Kam. LAND 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 22 nd May 2013
Borexino 2010 First “Observation of the Geo. Neutrinos”. (Physics Letters B Volume 687, Issues 4 -5, 19 April 2010, Pages 299 -304) events Absence of the geoν signal is rejected at 99. 997% C. L. Paris 22 nd May 2013
Neutrino Geoscience Japan, March 2013 New Borexino results http: //arxiv. org/abs/1303. 2571 New Kam. LAND results http: //arxiv. org/abs/1303. 4667 http: //www. awa. tohoku. ac. jp/geoscience 20 13/ Paris 22 nd May 2013
Modeling of Geo. Nu signal In order to extract the Geo neutrino signal (S) for U and Th for the given site on the Earth’s surface three components has to be considered: SExpected = SLOCal + SRest Of Crust + 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; 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; Kam. LAND G. Fiorentini et al. , Phys. Rev. D 86 (2012) 033004 Special thanks to Fabio Mantovani Paris 22 nd May 2013
Expected signal in Borexino 1) LOC: The detailed study of the Borexino site M. Coltorti et al, Geochimica et Cosmochimica Acta 75, 2271 (2011); 2) ROC: (2 o x 2 o) tiles geological map “CRUST 2. 0” + Y. Huang et al. , ar. Xiv: 1301. 0365; 3) Mantle = BSE – Crust (Low and High cases). Based on G. Fiorentini et al. , Phys. Rev. D 86 (2012) 033004. 1 TNU = 1 ev in 1032 protons / yr Expected in Borexino rate is: ~10 ev/yr/ LS mass 278 ton Paris 22 nd May 2013
Expected signal in Kam. LAND 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: (2 o x 2 o) tiles geological map “CRUST 2. 0” + Y. Huang et al. , ar. Xiv: 1301. 0365. 3) Mantle (BSE – Crust; Low and High cases). Paris 22 nd May 2013
Expected Geo-signals in BX & KL Borexino [TNU] Kam. LAND [TNU] LOC(Fiorentini et al. 2012) 9. 7 ± 1. 3 17. 7 ± 1. 4 ROC(Fiorentini et al. 13. 7 ± 2. 5 7. 3 ± 1. 4 CLM(Huang et al. 2013) 2. 2 ± 2. 2 1. 6 ± 1. 6 8. 7 8. 8 2012) Mantle(Huang et al. 2013) Thanks to Fabio Mantovani, Total 34. 3 ± 3. 6 see his talk @ http: //www. awa. tohoku. ac. jp/geoscience 2013/? page_id=269 35. 4 ± 2. 5 Paris 22 nd May 2013
Borexino & Kam. LAND ~3600 m. w. e. (Φµ = 1. 2 µ/m 2/hr); - Mean distance from reactor: ~1170 km; - 13 m S. S. Sphere, 2212 8” PMTs; - 8. 5 m Nylon Inner Vessel; - 278 tons of LS: (PC @ 1. 5 g/l PPO); - 18 m S. S. Water Tank, 2. 4 kt of HP H 2 O; - Muon veto: 208 8” PMTs: - Energy Resolution: 5%/√E(Me. V) ; - Vertex resolution: 11 cm/√E(Me. V). - Exposure: (3. 69± 0. 16)x 1031 proton x ~2700 m. w. e. (Φµ = 5. 4 µ/m 2/hr); - Mean distance from reactor: ~180 km; - 18 m S. S. Sphere, 1325 17”+554 20” PMTs; - 13 m Nylon Inner Baloon; - 1 kt of LS: (80%dodecan + 20%PC)@1. 36 g/l PPO; - 18 m S. S. Water Tank, 3. 2 kt of HP H 2 O; - Muon veto: 225 20” PMTs: - Energy Resolution: 6. 4%/√E(Me. V); - Vertex resolution: 12 cm/√E(Me. V). Paris 22 nd May 2013 32 proton - Exposure: (4. 9± 0. 1)x 10 x yr;
Geo neutrino analysis in Borexino Paris 22 nd May 2013
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 give 13% 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: ~1170 km 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 22 nd May 2013
Reactor anti-ν spectrum in Expected in Borexino In the whole spectrum: The diff. reactor anti-ν spectrum Sys. errors on the expected signal W oscill. : (33. 3± 2. 4) ev in (613± 26) ton x yr WO oscill. : (60. 4± 4. 1) ev in (613± 26) ton x yr Sum U 235 Pu 239 U 238 Pu 241 Paris 22 nd May 2013
Geo-ν signal in Borexino Expected in Borexino signal from the geo-ν's: Ideal expected spectrum Emax(U) = 3. 26 Me. V Emax(Th) = 2. 25 Me. V Emax(K) = 1. 3 Me. V MC with energy response of the detector. ~10 ev/yr in 278 tons Paris 22 nd May 2013
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 Me. V gamma, Am. Be data) 3) ∆R< 1 m (MC simulations); 4) 20µs < ∆t < 1280µs ( 5 tau of neutron, Am. Be source data t = (254. 5± 1. 8)μs ); 5) RIV – Rprompt > 0. 25 m (weekly reconstruction of the Vessel shape based on data); 6) Gdelayed < 0. 015 (Pulse Shape Analysis of Am. Be source data). Total detection efficiency determined with MC is 0. 84± 0. 01 Paris 22 nd May 2013
Borexino background The fiducial exposure after all cuts is (613 ± 26) ton ( × yr Expected signal from geo+reactors: ~10 ev + ~33 ev nd Paris 22 May 2013
Selected candidates After all cuts, in 1198. 9 d we select 46 candidates. Paris 22 nd May 2013
Unbinned maximal likelihood analysis Ingredients for the fit: Free: Ngeo , Nreac ; Constrained (± 1σ): Li. He , (α, n), accidentals. Signal/Background ~ 65: 1 Paris 22 nd May 2013
“Geo vs Reactors” In terms of signal: Sgeo = (38. 8± 12. 0) TNU 3σ Sreac = (84. 5 -16. 9+19. 3) TNU The null hypothesis (Sgeo= 0) is rejected at 99. 9994 % C. L. (4. 5σ) Full agreement with the expectation on the reactor anti neutrinos (33. 3± 2. 4) ev in the presence of neutrino oscillations. 2σ (high) 1σ (low) Paris 22 nd May 2013
Geo neutrino analysis in Kam. LAND Paris 22 nd May 2013
Three periods 3 months of shut down Period 1: 2002 -2007 with 1486 d Period 2: 2007 -2011 with 1154 d Period 3: 2011 -2012 with Paris 22 nd May 2013
Candidates selection & 2991 live days (Mar. 2002 - Nov. 2012) bkg 1) 0. 9 Me. V < Qp < 8. 5 Me. V ; 2) 1. 8(4. 4) Me. V < Qd <2. 6 (5. 6) Me. V (H/C); 3) ∆R< 2 m ; 4) 0. 5µs < ∆t < 1000µs ; 5) Rp, Rd < 6. 0 m; (Period 3: Rd > 2. 5 m & ρd>2. 5 m & Zd>0 m); The fiducial exposure is (4. 9± 0. 1)x 1032 proton x yr Total number of the reactor anti-nu expected: 1963. 76 ev Paris 22 May 2013 nd
Kam. LAND 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] SExpected geo = 35. 4± 2. 5 [TNU] The null hypothesis (Sgeo= 0) is rejected at 99. 9998 % C. L. Paris 22 nd May 2013
New Results Impact Paris 22 nd May 2013
Geo-ν signal vs BSEs BX best value +1σ SBXgeo = (38. 8± 12. 0) TNU SKLgeo = (31. 1± 7. 3) TNU -1σ KL best value The models differ by the contribution from the present Based on G. Fiorentini et al. , Phys. Rev. D 86 (2012) 033004. mantle. Both experiments are in agreement with available BSE models. Paris 22 nd May 2013
Earth radiogenic power Correlation between Sgeo(U+Th) and Hgeo(U+Th) is not straightforward. Sgeo (Crust)= (23. 4± 2. 8) TNU Borexino Sgeo (Crust)= (25± 2) TNU Kam. LAND ry a n i m i l io e b r a P F o t ks n a Th (Crust) 3. 3 yr, (3. 69± 0. 16)x 1031 prot x yr Sgeo = (38. 8± 12. 0) TNU (BX) = (23± 14)TW Heat 8. 2 yr, (4. 9± 0. 1)x 1032 prot x y Sgeo = (31. 1± 7. 3) TNU ry. Heat (KL) = (13± 9)TW a n i m Preli Paris 22 nd May 2013
Signal from the Mantle N(geo) = N (Crust) + N (Mantle) Borexino : S BX geo (Total)= (38. 8± 12. 0) TNU S BX geo (Crust)= (23. 4± 2. 8) TNU SBX geo (Mantle) = (15. 4± 12. 3) TNU Kam. LAND: S KL geo (Total)= (31. 1± 7. 3) TNU S KL geo (Crust)= (25± 2) TNU SKL geo (Mantle) = (6. 1± 7. 6) TNU Paris 22 nd May 2013
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 Paris 22 nd May 2013 chondritic value.
Summary For the first time the same level of compatibility is observed at two different sites: Gran Sasso in Italy and Kamioka in Japan. SBX geo = (38. 8± 12. 0) TNU. Null hypothesis is rejected at 99. 9994 C. L. SKL geo = (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 + Kam. LAND 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, 10 th kt scale, multi-site detection: SNO+, Hanohano, LENA, Daya Bay. II. . . Paris 22 nd May 2013
The End
BX vs KL bkg Paris 22 nd May 2013
Anti-ν sources Electron anti-ν from The Earth Interior Electron anti-ν from the Nuclear Power plants Paris 22 nd May 2013
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