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Neutrinos from the sun, earth and SN’s: a brief excursion

Neutrinos from the sun, earth and SN’s: a brief excursion. Aldo Ianni @ IFAE 2006 Pavia April 19 th. Outline. Solar neutrinos: established facts Solar neutrinos: the future Neutrinos from the Earth: present & future Neutrinos from SN. Solar neutrinos. Pure n e beam Low energy

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Neutrinos from the sun, earth and SN’s: a brief excursion

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  1. Neutrinos from the sun, earth and SN’s: a brief excursion Aldo Ianni @ IFAE 2006 Pavia April 19th

  2. Outline • Solar neutrinos: established facts • Solar neutrinos: the future • Neutrinos from the Earth: present & future • Neutrinos from SN

  3. Solar neutrinos • Pure ne beam • Low energy • Long baseline (1013 cm) • Moving through high density matter (at sun’s core ~150 g/cm3)

  4. Solar neutrinos: observations * Super-Kamiokande recovers full detector performances this year ** SNO is planned to be shut down end of this year

  5. Phenomenology of solar neutrino observations • Observations explained by neutrino oscillations + matter effects (MSW) • MSW leads to energy spectrum distortion and regeneration in the earth (day-night effect) • After SNO with NC the space of parameters gets reduced a lot • After KamLAND (assuming CPT) one dominant solution is tackled, namely the LMA

  6. The great turn with SNO (>2001)

  7. Established dominant solution Taken from V. Barger et al hep-ph/0501247 Taken from G.L.Fogli et al hep-ph/0506083

  8. Established facts • 0.01% of solar neutrinos measured in real time • Data explained by the MSW LMA • MWS defines mass hierarchy (m2 > m1) • SNO CC/NC sets tan2q12<1 • MSW predicts up-turn of survival probability (spectral distortion) and regeneration • MSW predicted effects not yet observed in SNO and SK due to high systematrics and still poor statistics

  9. SNO data

  10. A look at the future for Solar neutrinos • Measure in real time 99.99% of spectrum below 5 MeV : low energy detectors • Measure spectral distortion and regeneration : low energy and/or Mton water Cherenkov • Compare photon to neutrino luminosity : low energy solar neutrinos pp, pep, Be • Test new physics with sub-dominant effects : e.m. properties, mass varying neutrinos, non-standard interactions, light sterile neutrino

  11. Borexino @ Gran Sasso A pioneering experiment to search for sub-MeV 7Be solar neutrinos • Target medium : 100tons of high radiopurity organic liquid scintillator • Detection channel: neutrino-electron elastic scattering (about 30cpd expected) • Signature : seasonal variation + Compton-like threshold due to monoenergetic 7Be neutrinos • Challenge : reduce background sources (238U, 232Th, 40K, 222Rn, 85Kr, 39Ar, 210Pb, 210Po) to get S/N>1 • Lower detection energy : 250 keV limited to intrinsic 14C contamination • Experimental strategies to reduce background : established by a 4-ton scale prototype

  12. pep neutrinos with Borexino • Basic idea : reduce 11C cosmogenic background • Method: tagging 11C by tackling the produced (95%) neutrons in spallation interactions Taken from C. Galbiati et al PRC 71, 055805 (2005) Remark: a pep measurement gives the same information of a pp one

  13. Spherical cut aroundneutron Capture to reject 11C event Cylindrical cut Around muon-track Reduction of background forpep neutrinos Muon track Neutron production

  14. 11C tagged with the Borexino prototype 11C decays b+ with Qb~1MeV and t~30min Measured production rate ~0.14 events/day/ton at Gran Sasso depth Taken from Borexino coll. hep-ex/0601035

  15. Predictions to falsify with Borexino Bahcall et al, JHEP 8 (2004) 016, hep-ph/04060294 2 monoenergetic beams to test solar physics and neutrino physics

  16. pep new goal for KamLAND-II Taken from Nakajima, La Thuile

  17. pep for SNO+ • Main physics goal for 1kton organic liquid scintillator after SNO • At SNOlab 11C is reduced by a factor of about 10 with respect to Gran Sasso and 70 to Kamioka

  18. Searching for pp solar neutrinos • Goal : no 14C or a strong tagging • Solution-I : liquid Ne(CLEAN) or Xe(XMASS), detection channel = ES • Solution-II : loaded 115In liquid scintillator (LENS) • Solution-III : 100Mo sheets + plastic scintillator • Time scale : due to experimental difficulties >2010

  19. Conclusions on solar neutrinos • Wonderful effort made by researchers (both on experiments and theory) to collect and explain data • Unique opportunity with low energy solar neutrinos both in astrophysics and neutrino physics • A great challenge for experiments • pep neutrinos measurable • Not too much to add to oscillation parameters

  20. Neutrinos from the earth: geoneutrinos • Goals: • determine distribution of U, Th and K in earth interior • measure total heat due to radioactivity [earth gives 30-44 TW] • determine hot spots (geo-reactor etc) if any

  21. Detection of geoneutrinos Above 1.8MeV (only U,Th): inverse-beta decay (strong tagging) Below 1.8MeV (K as well): elastic scattering (weak tagging)

  22. The earth looked through geoneutrinos Geoneutrino flux (Fiorentini et al) Middle oceanic crust KamLAND SNO+ Lena 30kt Borexino

  23. Present observations @ KamLAND • Energy window: 0.9<E<2.6 MeV • Observed : 152 events • Background : 127 ± 13 events • Geoneutrino signal : 25+19-18 events • Main sources of background : reactors and 13C(a,n)16O with a’s from 210Po

  24. Geoneutrinos @ Gran Sasso Borexino 300t target mass : S/N~1

  25. LENA in Finland • Proposeda 30kt multi-puspose liquid scintillator based on PXE • PXE tested with the Borexino prototype • High statistics and angular resolution (26°) may allow 40K neutrino measurement looking toward the earth’s nucleus (if any hidden K in there!)

  26. Conclusions on geoneutrinos • U and Th geoneutrinos to get information on radiogenic heat on earth and test earth formation mechanism • U and Th geoneutrinos easy to detect far away from reactors and with a low background liquid scintillator • More detectors in different locations to reduce uncertainties • First (2s) evidence of geoneutrinos from KamLAND • Hope : detect K neutrinos somehow. See M. Chen talk at Neutrino Geophysics, Honolulu, Hawaii December 15, 2005

  27. SN neutrinos

  28. Detection of SN neutrinos [1] • SN neutrinos are affected by oscillations: • In the standard figure each flavor has a peculiar mean energy and temperature (Te~3.5MeV, Tanti-e~5MeV, Tx~8MeV with <E>~3.15T) • Uncertainty of standard figure ~50% • SN in galaxy: 40±10 yr/SN. Long-term stability of detectors required • in order to measure the temperature and energy of x’s and their antiparticles one needs a spectral signature ne nanti-e nx

  29. Detection of SN neutrinos [2] • SuperKamiokande will play a crucial role with ~8000 events for inverse-beta decay and ~700 for NC on 16O @10kpc • SuperKamiokande will see ~300 events of antineutrino @50kpc in the LMC • SNO has a unique channel e +dppe- for studying the neutronization phase but it will be shut down in 2007 • NC with neutrino-proton elastic scattering to measure x’s and their antiparticles with a spectral signature in low threshold liquid scintillators (Borexino, KamLAND) • Italy has a great opportunity with LVD, T600 and Borexino at the same location

  30. Detection of SN neutrinos [3]

  31. Conclusions on SN neutrinos • A future galactic SN will yield 100-1000 events in the existing detectors for the well tagged channel of inverse-beta decay (electron-antineutrino spectral signature) • Neutrino-proton elastic scattering will allow to measure the energy and temperature of mu and tau (anti)neutrinos • Collection of nice data for the cooling phase, not as well for the neutronization phase after SNO shut-down • Future proposed LENA to see modulation of spectra due to matter effect in the earth

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