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Marco G. Giammarchi Istituto Nazionale di Fisica Nucleare Via Celoria 16 – 20133 Milano (Italy)

Solar Neutino Physics with Borexino Rencontres de Physique de La Vallée d’ Aoste - 2012. Marco G. Giammarchi Istituto Nazionale di Fisica Nucleare Via Celoria 16 – 20133 Milano (Italy) marco.giammarchi@mi.infn.it http://pcgiammarchi.mi.infn.it/giammarchi/. 1. BOREXINO

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Marco G. Giammarchi Istituto Nazionale di Fisica Nucleare Via Celoria 16 – 20133 Milano (Italy)

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  1. SolarNeutinoPhysicswithBorexino Rencontres de Physique de La Vallée d’Aoste - 2012 Marco G. Giammarchi Istituto Nazionale di Fisica Nucleare Via Celoria 16 – 20133 Milano (Italy) marco.giammarchi@mi.infn.it http://pcgiammarchi.mi.infn.it/giammarchi/ 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future La Thuile - 27 Feb 2012

  2. 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future 1. BOREXINO Borexinois a low background Neutrino Detector forsub-MeVsolar Neutrino (and other) studies DetectingSolarNeutrinosmeans: • Low interactionrates: 0.1/1 event/day/ton of target mass • Low energy (mostly <10 MeV, betterif <2 MeV) • Low threshold and low background • Underground location toshieldfromcosmicrays La Thuile - 27 Feb 2012

  3. Experimental site Laboratori Nazionali del Gran Sasso Assergi (AQ) Italy 1400m of rock shielding ~3800 m.w.e. Abruzzo, Italy 120 Km from Rome External Labs Borexino Detector and Plants La Thuile - 27 Feb 2012

  4. The Borexino Detector Stainless Steel Sphere: • 2212 PMTs • ~ 1000 m3 buffer of pc+dmp (light queched) Neutrino electron scattering ne ->n e Scintillator: 270 t PC+PPO (1.4 g/l) Nylon vessels: (125 μm thick) Inner: 4.25 m Outer: 5.50 m (radon barrier) Water Tank: γ and n shield μ water Č detector 208 PMTs in water 2100 m3 Carbon Steel Plates 2020 legslegs La Thuile - 27 Feb 2012

  5. Fillingphaseof the Borexino detector (2007, Laboratorio del Gran Sasso) 11 m Planetario di Milano - 21 Febbraio 2012 La Thuile - 27 Feb 2012 5

  6. Energy production in the sun PP-chain >99% energy production 5 νspecies CNO-cycle <1% energy production 3 νspecies La Thuile - 27 Feb 2012 6

  7. Solar Neutrino Spectrum ,Borexino La Thuile - 27 Feb 2012 7

  8. StudyofSolarNeutrinos Solar Neutrino Problem  Neutrino Oscillations La Thuile - 27 Feb 2012 8

  9. Neutrino OscillationSolution Open Issues La Thuile - 27 Feb 2012 9

  10. 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future 2. Be-7 fluxmeasurement Eν = 862 keV (monoenergetic) ΦSSM = 4.8· 109 ν s-1 cm2 νe νx Electron recoil spectrum Cross Section  10-44 cm2 (@ 1MeV) La Thuile - 27 Feb 2012

  11. LMA La Thuile - 27 Feb 2012 11

  12. 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future 3. B-8 measurement • Analysiswith 3 MeVthreshold • Borexino rate : ≈ 0.2 cpd / (100 tons) • Backgrounds: • Muons, Neutrons • External background • Fast cosmogenics • C-10, Be-11 • Tl-208,Bi-214 La Thuile - 27 Feb 2012

  13. La Thuile - 27 Feb 2012 13

  14. 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future 4. Geoneutrinos AntiNeutrinosemitted in beta decaysofnaturallyoccurreingradioactiveisotopes in the Earth’s crust and mantle Moderate NuclearReactorsbkgd at LNGS Detection by Inverse Beta Decay (1.8 MeVthr.) Geo-nu and nuclearreactornu Geo-nu Positron-Gamma (2.2 MeV) delayedcoincidence La Thuile - 27 Feb 2012

  15. Searchfordelayedcoincidences in the Borexino detector • Main background sources: • Li-9, He-8, untaggedmuons, accidentals……………. 68.3 %CL 99.73 %CL La Thuile - 27 Feb 2012 15

  16. 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future 5. Pep first detection p + e - + p d + e Pepreaction Monoenergetic 1.44 MeV neutrinos La Thuile - 27 Feb 2012

  17. Planetario di Milano - 21 Febbraio 2012 La Thuile - 27 Feb 2012 17

  18. Going for pep and CNO: 11C tagging The main background for pep and CNO analysis is 11C, a long lived (τ=30min) cosmogenicβ+ emitter with ~1MeV end-point (shifted to 1-2MeV range) τ (n capture): ~250μs μ 11C Production Channels: [Galbiati et al., Phys. Rev. C71, 055805, 2005] • 95.5% with n: (X,X+n) • X = γ, n, p, π±, e±, μ. • 4.5% invisible : • (p,d); (π+,π0+p). n γ β τ (11C): ~30min 11C rate = (28.5 ±0.5) cpd exp. pep rate ~ 3cpd La Thuile - 27 Feb 2012

  19. Electron/Positrondiscrimination due toPsformation in positronevents (D. Franco, G. Consolati and D. Trezzi, Phys. Rev. C 83 (2011) 015504 La Thuile - 27 Feb 2012

  20. C-11 reductionstrategy: • Threefoldcoincidence (muon,neutron,C11) • Pulseshapediscrimination electron/gamma/positron (Psformation) First pepmeasurement and the best CNO limit La Thuile - 27 Feb 2012 20

  21. 1. BOREXINO 2. Be-7 fluxmeasurement 3. B-8 measurement 4. Geoneutrinos 5. Pep first detection 6. Future 6. Future (summary) • SolarNeutrinos: • Earlymotivation studyof the Sun • Unexpectedfinding  neutrino oscillations SolarNeutrinostoday: Studyof the P(ee) oscillation pattern as a functionofenergy Studyof the interiorof the Sun La Thuile - 27 Feb 2012

  22. Neutrino Oscillations PMNS neutrino mixing matrix, analogous to CKM matrix for quarks Solution of the Solar Neutrino Problem is neutrino oscillation with matter (MSW) effect at Large Mixing Angle (LMA) La Thuile - 27 Feb 2012

  23. Solar neutrino components measured by Borexino ,Borexino Planetario di Milano - 21 Febbraio 2012 La Thuile - 27 Feb 2012 23

  24. Neutrino OscillationspropertiesmeasuredbyBorexino Solar electron neutrino survivalprobabilityas a functionof neutrino energy LMA-MSW with standard neutrino interactions La Thuile - 27 Feb 2012 24

  25. Futuresperspectives Detector stillfullyoperationalafteralmostfiveyearsofrunning Purificationcapabilitytobeimproved Deal withresidualbackgrounds • Measurementof the CNO solarcomponent • Measurementof short baseline neutrino oscillationswith a radioactivesource • Neutrino magnetic moment • Supernova alert system (SNEWS) • Measurementof neutrino speed (CNGS beam) La Thuile - 27 Feb 2012

  26. Thankyouforyourattention (& selectedbibliography) • G. Alimontiet al., Nucl. Instr. & Methods A600 (2009) 568 Detector • C. Arpesellaet al., Phys. Lett. B 568 (2008) 101 • C. Arpesellaet al., Phys. Rev. Lett. 101 (2008) 091302 • G. Bellini et al., Phys. Rev. Lett. 107 (2011) 141302 • G. Bellini et al., Phys. Lett. B 707 (2012) 22 Be-7 • G. Bellini et al., Phys. Rev. D 82 (2010) 033006 B-8 • G. Bellini et al., Phys. Lett. B 687 (2010) 299 Geoν • G. Bellini et al., Phys. Rev. Lett 108 (2012) 051302 pep La Thuile - 27 Feb 2012 26

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