1. Solar and geo neutrinos  in Borexino: summary of the PHASE 1 measurements and (two) new results Gemma Testera - INFN Genova (on behalf of the Borexino Collaboration) Neutrino Telescopes – Venice - March 11-15th 2013

2. Water Tank:  and n shield  water Č detector 208 PMTs in water Scintillator: 270 t PC+PPO (1.5 g/l) in a 150  m thick inner nylon vessel (R = 4.25 m) Stainless Steel Sphere: R = 6.75 m 2212 PMTs Outer nylon vessel: R = 5.50 m ( 222 Rn barrier) Buffer region: PC+DMP quencher 4.25 m < R < 6.75 m The smallest radioactive background in the world: 9-10 orders of magnitude smaller than the every-day environment The Borexino detector @ LNGS (Italy)  ≈500 phe/MeV (electron equivalent)  Energy resolution 4.5%@1MeV  Space resolution 10 cm @1MeV  “wall less” Fiducial Volume  Pulse shape capability  Calibration in situ with radioactive sources  Accurate Monte Carlo modeling of the energy and time response function detection: elastic scattering on electrons

3. 13 N 17 F Solar neutrino spectrum predicted by the Standard Solar Model (SSM) pp 7 Be 8B8B hep pep 15 O Neutrino energy (MeV) Flux (cm -2 sec -1 MeV -1 ) CNO cycle Borexino

4. Why solar  Solar model prediction and  e survival probability  sec -1 cm -2 ) High Metallicity  sec -1 cm -2 ) Low Metallicity Diff. % pp5.98 (1 ±0.006) 10 10 6.03 (1 ±0.006) 10 10 0.8 pep1.44 (1 ±0.012) 10 8 1.47 (1 ±0.012) 10 8 2.1 7 Be5.00 (1 ±0.070) 10 9 4.56 (1 ±0.070) 10 9 8.8 8B8B5.58 (1 ±0.14) 10 6 4.59 (1 ±0.14) 10 6 17.7 13 N2.96 (1 ±0.14) 10 8 2.17 (1 ±0.14) 10 8 26.7 15 O2.23 (1 ±0.15) 10 8 1.56 (1 ±0.15) 10 8 30.0 17 F5.52 (1 ±0.17) 10 6 3.40 (1 ±0.16) 10 6 38.4 Aldo M. Serenelli et al. 2011 ApJ 743 24 CNO Solar model flux prediction Vacuum region Non standard neutrino interaction: P ee (E) with different shape  e survival probability: LMA-MSW  without the Borexino results Matter region LMA-MSW Neutrino oscillations

5. Solar PHASE 1 and PHASE 2 May 2007May 2010 Solar PHASE 1 Data taking and calibration Scintillator purification Aug. 2011 Solar PHASE 2  First solar 7 Be measurement  Absence of 7 Be day night  Low threshold 8 B  First pep detection  Best upper limit on CNO  geo measurement  Muon analysis  Limit on rare processes  evidence of 7 Be seasonal modulation ( NEW: to be presented now) n e Oct. 2011 New geo  results: Dec2007-Aug2012 Borexino Coll. Arxiv…. (NEW: to be presented now)

6. 0.862 MeV 7 Be solar : fit of the energy spectrum Identify background Accurate modeling of the response function (Monte Carlo and analytical models) Fit of the energy spectrum Calibration to reduce errors pp, pep, 8 B fixed 210 Po a peak Fiducial Volume: 75 t radial and z cut R<3m; |z|<1.67 m G. Bellini et al., Borexino Collaboration, Phys. Rev. Lett. 107 (2011) 141362. Counts/day 100t 5  evidence of oscillation G. Bellini et al., Borexino Collaboration +C Pena Garay, Phys. Lett. B707 (2012) 22.  e flux reduction 0.62 +- 0.05  electron neutrino survival probability 0.51 +- 0.07 @0.862MeV

7. The first pep solar detection: multivariate analysis and background subtraction  Expected pep interaction rate: 2-3 cpd/100t  Background: 11 C 210 Bi external   210 Bi and CNO spectra: very similar  Three Fold Coincidence: 11 C reduction  Novel pulse shape discrimination: e + from 11 C decay form Positronium live time before annihilation in liquid: few ns delayed scintillation signal (Phys. Rev. C 015522 (2011)) Multivariate analysis:  fit of the energy spectra  fit the radial distribution of the events ( external background is not uniform)  fit the pulse shape parameter pep CNO 210 Bi 11 C G. Bellini et al., Borexino Collaboration, Phys. Rev. Lett. 108 (2012) 051302..

8. muon n capture on H:  2.2 MeV Space and time Veto Residual exposure 48.5% 11 C reduction and pep-CNO results Interaction point and 11C production point Position of the  Spectrum after TFC Spectrum before TFC Interaction Rate (cpd/100t) DATA/SSM (high met.) Counts/(days 100 t)ratio pep3.1±0.6 (stat) ± 0.3(sys)1.1±0.2 CNO<7.9 95% C.L.<1.5  The CNO limit does not allow to select high or low metallicity  Best upper limit on CNO

9. Physics implication of the solar Borexino results: the Neutrino Survival Probability P ee (E) Before the Borexino results G. Bellini et al., Borexino Collaboration, Phys. Rev. Lett. 108 (2012) 051302.. First solar pep neutrino detection G. Bellini et al., Borexino Collaboration, Phys. Rev. Lett. 107 (2011) 141362. High precision 7Be solar neutrino measurement G. Bellini et al., Borexino Collaboration, Phys. Rev. D82 (2010) 033006. 8 B flux with a threshold of 3MeV (e- recoil) Combined analysis Borexino&solar

10. Physics implication of the solar Borexino results: high and low metallicity solar models High met. (1  ) Low met. (1  ) Data

11. New result: annual modulation of the 7 Be signal (PHASE 1)  =0.0167 max flux: Jan. 3rd Expected amplitute of 7 Be signal 6.8% peak-to-peak Spectral fit in sub-periods: too large stat. errors Analysis method:  Select a proper energy region, group data in time bins and search for a periodical component  Enlarge the fiducial volume (with respect to the 7 Be flux meas.) 3 methods (consistent results)  Fit of the rate vs time  Lomb Scargle analysis  Empirical Mode Decomposition 7 Be interaction rate cpd/100t 46 44.5 47.5 Time (years)

12. New result: annual modulation of the signal (PHASE 1) The challenge: amplitude of some untaggable background ( 210 Bi) not stable in time Background shape reproducible during time (no new components!) Counts in a energy region dominated by 210 Bi DETECTOR RESPONSE very stable: Energy scale stability: 210 Po peak statibility in the enlarged (145 t) FV : rms/peak 0.8 % Pulse shape discrimination and position reconstruction: no detectable issue about stability 210 Po peak distribution in PHASE 1

13. Data selection and FV Enlarged (double) FV compared to 7 Be flux meas. Vessel shape and position change during time Measure week by week the vessel shape and position (using radioctive decay of vessel contaminants) Low background: we need 1 week of data! Reconstructed vessel shape Fiducial volume for seasonal analysis (145 t) Distance from vessel 75 cm 7 Be flux FV

14. Data selection and FV 210 Po rate is also time dependent Remove 210 Po by pulse shape discrimination Hard cut No spectral fitting: spectra deformation not relevant Rate analysis Pulse shape discrimination parameter vs energy (Npe) 210PoDATA sample for seasonal variation analysis: standard cut as in the 7 Be flux + removal of the events above the red line 7 Be energy region

15. Annual modulation of the signal (PHASE 1): counts vs time Counts in 60 days in the 7 Be energy region  Chi 2 profile T=1.01 +- 0.07 y  =0.0398 +-0.0102 expected values are within the 2  contour

16. Annual modulation of the signal (PHASE 1): Lomb Scargle analysis Peak at period 0.979 Year Spectral power density: 7.96 Null hypothesis: no seasonal effect With seasonal effect Monte Carlo distribution of the Spectral Power Density no seasonal effect: excluded at more than 3  11 22 33

17. annual modulation of the signal (PHASE 2): counts vs time results after the scintillator purification Rate vs time in the 7 Be energy region PRELIMINARY

18.  Low flux: 3 order of magnitude less than 7Be solar !  Geo : they probe the U,Th content of the Earth (no K)  Multidisciplinary research: particle physics&geophysics geo : new Borexino results E >1.8 MeV “prompt signal” e+: energy loss + annihilation (2  511 KeV each) “delayed signal” n capture after thermalization 2.2  Previous Borexino result : G. Bellini et al., (Borexino Coll.) Phys. Lett. B 687 (2010) 299 Kamland: T. Araki et al., (Kamland Coll.) Nature 436 (2005) 499; A. Gando et al. (Kamland Coll.) Nature Geoscience 4 (2011) 574 new Bx result: http://arxiv.org/abs/1303.2571 Energy spectrum of geo neutrinos Previous data Dec 2007-Dec2009 252.6 ton year New data (2.4 X) Dec 2007-Aug2012 613.0 ton year (3.69 ± 0.16) 10 31 proton year

19. Main background: anti from reactor (see Poster here) 1MeV≈ 500 p.e. reactor geo geo : signal and background Monte Carlo simulation of the geo and reactor signal 446 reactors Data from IAEA

20. geo : signal and background Event selection  Q prompt >480 pe Q delayed (860,1300)   R (promt-delayed): 1m   t (promt-delayed): (20  s, 1280  s)  Veto after muon: up to 2 s  Pulse shape discrimination (Gatti filter) <0.015 : delayed events must be “beta like”  Total cut efficiency determined by Monte Carlo: 0.84±0.01  Large Fiducial Volume: distance from the vessel <25 cm Dynamical vessel shape as in the seasonal analysis  Exposure 613±26 ton year (vessel shape 1.6%; posit. rec. 3.8%; cut eff 1%) 46 candidates Background not due to reactors is very small 0.70 ±0.18 events

21. geo results: evidence of the signal N reactor Expected with osc. N reactor Expected no osc. Others back. N geo measured N reactor measured N geo measured N reactor measured eventsEventsevents TNU 33.3±2.460.4±2.40.70±0.1814.3±4.4 9.9 +4.1 -3.4 31.2 -6.1 +7 38.8±12.084.5 +19.3 -16.9 reactor geo No geo signal: rejected with prob. 6 10 -6 Unbinned likelihood fit 1  expectation N reactor (TNU) N geo (TNU) TNU=1ev/ (y 10 32 protons) 68.3 C.L. 95.5 C.L. 99.7 C.L. Our previous result

22. geo results: U and Th separation Chondritic U-Th ratio Best fit S( 238 U)= 26.5 ± 19.5 TNU S( 232 T) = 10.6 ± 12.7 TNU Fit with weight of 238 U and 232 Th spectra free

23. geo results: comparison with expectation Crust contribution: from local geolog. at G. Sasso Mantle contribution: BSE Earth models Borexino result +1  -1  Borexino result compared with various BSE models (see our paper for details) Result consistent with expectation We cannot yet discriminate between different models

24. geo results: Borexino+Kamland combined Mantle contribution combining the results of : Kamland A. Gando et al. (Kamland Coll.) Nature Geoscience 4 (2011) 574 : S KL (U+Th) = 31.8 ± 12.6 TNU Borexino S Bx (U+Th) = 38.8 ± 11.9 TNU Crust (LOC+ROC) contribution calculated according to G. Fiorentini et al., Phys. Rev. D 86, 033004 (2012) S KL (crust)= 25.0 ± 1.9 TNU for Kamland S Bx (crust)= 23.4 ± 2.8 TNU for Borexino Spherical mantle S geo (mantle)= 14.1±8.1 TNU

25. geo results: radiogenic heat  Contribution of the radioacative decays of 238U and 232 Th to the total radiogenic heat?  Errors on the geo flux still large  Kamland and Borexino results very similar ( two different places)

26. Toward the Borexino PHASE 2 and more After the purification of the scintillator 1)Krypton: strongly reduced: consistent with zero cpd/100t from spectral fit 2) 210 Bi : from ~70 cpd/100tons to 20 cpd/100tons) ; 3) 238 U (from 214 Bi-Po tagging) < 9.7 10 ‐19 g/g at 95% C.L. 4) 232 Th < 2.9 10 -18 g/g at 95% C.L. 5) 210 Po 6)It may be possible to estimate the 210 Bi content from 210 Po evolution in time; Physics goals on PHASE 2 Improve limit on CNO (observation?); ( 210 Bi suppression required); Improve significance of pep signal (3  or more) 210 Bi suppression required; Search for pp neutrinos ( 85 Kr suppression helps); Improve precision on 7 Be neutrinos ( 210 Bi and 85 Kr suppression required); SOX: A Short Baseline neutrino oscillation experiment with Borexino see the talk of M. Pallavicini

27. 0.862 MeV 7 Be solar : fit of the energy spectrum Identify background Accurate modeling of the response function (Monte Carlo and analytical models) Fit of the energy spectrum Calibration to reduce errors pp, pep, 8 B fixed 210 Po a peak Fiducial Volume: 75 t radial and z cut R<3m; |z|<1.67 m G. Bellini et al., Borexino Collaboration, Phys. Rev. Lett. 107 (2011) 141362. Counts/day 100t

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29. 7 Be: fit of the energy spectrum 5  evidence of oscillation  e flux reduction 0.62 +- 0.05  electron neutrino survival probability 0.51 +- 0.07 @0.862MeV Search for a day night effect: not expected for 7 Be in the LMA-MSW model Large effect expected in the “LOW” solution (excluded by solar exp+Kamland) G. Bellini et al., Borexino Collaboration +C Pena Garay, Phys. Lett. B707 (2012) 22.

30. Oscillation parameter regions allowed by solar without BOREXINO and without anti from Kamland A small portion of the “LOW” region is not excluded Borexino (mainly the A dn data) + all solars select the LMA region without anti data (so without assuming CPT) Physics implication of the solar Borexino results: global analysis without anti results from Kamland All solar exp. including Borexino Region excluded By Borexino All solar exp. without Borexino