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Solar Neutrinos Hamish Robertson Erice, Sept. 18, 2005

Solar Neutrinos Hamish Robertson Erice, Sept. 18, 2005. Neutrino Sun, Super-Kamiokande. John Bahcall 1935 - 2005. Letter from Vladimir Gavrin, INR, Baksan Observatory, to Art McDonald, SNO. Dear Art,

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Solar Neutrinos Hamish Robertson Erice, Sept. 18, 2005

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  1. Solar Neutrinos Hamish Robertson Erice, Sept. 18, 2005 Neutrino Sun, Super-Kamiokande

  2. John Bahcall 1935 - 2005

  3. Letter from Vladimir Gavrin, INR, Baksan Observatory, to Art McDonald, SNO Dear Art, It is difficult to express my feelings with John Bahcall's passing because of our friendship and shared scientific experiences for many years. His contributions to modern physics are highly appreciated in Russia as well as throughout the world. His passing has orphaned neutrino astrophysics. It is an unrecoverable loss for world science and a huge personal grief for many of us. John was not only a great scientist, he was also a fatigueless fighter for science. And many people are grateful to him for this. There are a number of outstanding successful projects in the world that have been developed thanks to his active encouragement and efficient support. One of the bright examples was his help to save the gallium in SAGE. For five years he fought together with Russian scientists against numerous encroachments on SAGE gallium. These were difficult times in Russia and he wrote in The New York Times "It just astonishes me, that such magnificent science can continue at all in such a lawless country". Currently Russia has almost returned to the frames of civil community. John always provided support when his help was needed. He involved the world scientific community to support SAGE at that time with the result that a letter was written from 12 Nobel Prize Winners to Russian Prime Minister Chernomyrdin in 1997 to preserve the gallium in SAGE. Thanks to his efforts, the issue about preserving gallium in SAGE was raised in 1998 in the Intergovernmental Russian-American Commission Gore-Chernomyrdin, and that was extremely helpful. Also his letter to the President of Kabardino-Balkarian Republic played a significant role when local people stopped our 51Cr source on its way to the Baksan Neutrino Observatory. The scientific insight of John Bahcall, his personal spell, infecting enthusiasm, and energy allowed him to create a powerful international school of neutrino astrophysicists, and to attract interest of a wide non-scientific community to most intriguing problems in the field that to great extent provided proper financial support to neutrino astrophysics and astronomy now in the world. You are right, many things will not be the same without John. We will feel emptiness for a long time. Sincerely, Vladimir Gavrin

  4. 1998 1999 2000 2001 2002 2003 2004 2005 2006 Solar Neutrino Program Comm. D2O Return Data Analysis D2O Salt SNO D2O 3He Super-Kamiokande Cl-Ar Borexino SAGE & GNO KamLAND KamLAND Solar

  5. Super-K Flux:  = 0.021 ± 0.003 95% CL SNO/SK/KL All Solar/KL hep-ph/0508053

  6. The SNO Detector 6800 feet underground Acrylic vessel (AV), 12 m diam. 1000 tonnes D2O 1700 tonnes H2O inner shielding 5300 tonnes H2O outer shielding ~9500 PMTs, 54% coverage

  7. s = 44 b Advantages of Salty D2O (I) 35Cl+n s = 0.0005 b 2H+n 8.6 MeV 6.0 MeV 1. Higher capture cross-section means more neutrons detected 2. Boosts energy of NC events further above analysis threshold … 3H 36Cl (PRL 92, 181301, 2004)

  8. Advantages of Salty D2O (II) qij 3. Multiple gammas for NC means light is more isotropic than for CC, ES Define an “isotropy parameter” based on Legendre polynomials in θij B14 stuff here Allows point by point separation of NC and CC on a statistical basis

  9. Probability Density Functions for Signal Extraction Energy Isotropy Direction Radius

  10. CC: 2176 ± 78 NC: 2010 ± 85 ES: 279 ± 26 External n: 128 ± 42 Backgrounds (fixed in fit): 128 Results from the full 391 days of salt data (spectrum shape unconstrained) 4722 events (r < 550cm, Teff > 5.5MeV) Isotropy

  11. CC: 2176 ± 78 NC: 2010 ± 85 ES: 279 ± 26 External n: 128 ± 42 Backgrounds (fixed in fit): 128 Results from the full 391 days of salt data (spectrum shape unconstrained) 4722 events (r < 550cm, Teff > 5.5MeV) Direction

  12. CC: 2176 ± 78 NC: 2010 ± 85 ES: 279 ± 26 External n: 128 ± 42 Backgrounds (fixed in fit): 128 Results from the full 391 days of salt data (spectrum shape unconstrained) 4722 events (r < 550cm, Teff > 5.5MeV) AV FV Radius

  13. 391- day salt results!

  14. D2O: shape-constrained Salt: shape-constrained Salt: shape-unconstrained CC flux NC flux Comparing Salt to D2O: Fluxes Salt phase improves determination of NC flux and allows model-independent signal extraction

  15. Extracted CC spectrum with statistical and systematic uncertainties CC Spectrum CC spectrum consistent with LMA and undistorted 8B

  16. Day-night Asymmetry D2O Salt

  17. Zenith angle and energy dependence “regeneration factor” for SNO CC events vs. zenith angle, averaged over different energy regions (future work: explore zenith and energy dependence?) Figure from de Holanda, Liao, Smirnov, hep-ph/0404042, May 2004 For: Δm2 = 6.3x10-5, tan2θ=0.40

  18. Significance > 98% at 9.43 yr-1 Ampl: 6.6% Search for Periodicities in Solar  Data hep-ph/0501205

  19. D2O data: 2924 events, 572 days Salt data: 4722 events, 763 days (calendar) Search at 9.43 yr-1: Ampl: 1.3 ± 1.6% Search for Periodicities in SNO  Data SNO: hep-ex/0507079

  20.  = 0.014(9). Actual: 0.0167 Orbital Eccentricity  = 0.021(3) SNO: hep-ex/0507079 SK: hep-ex/0508053

  21. SNO data fixes q, KamLAND fixes Dm2 Global solar data + KamLAND 766 ton-y nucl-ex/0502021

  22. Oscillation Parameters, 2-D joint 1-s boundary Marginalized 1-D 1-s errors Results from SNO -- Salt Phase SNO D2O D/N spectra SNO Salt D/N spectra KamLAND 766-day SK-I zenith spectra SAGE Gallex/GNO Cl/Ar

  23. The Neutral Current Detectors

  24. Installed 3He Counter Strings 3He 4He N

  25. Pulse Shapes neutron with p-t track  wire neutron with p-t track || wire 14 1.5 12 10 1.0 De-logged current De-logged current 8 0.5 6 4 0.0 2 0 -0.5 0 2 4 6 8 0 2 4 6 8 Time (microseconds) Time (microseconds) a track  wire 20 15 De-logged current 10 5 0 0 1 2 3 4 5 Time (microseconds) Current preamplifiers (T. Van Wechel) allow digitization of pulse shapes for particle identification.

  26. Salt 391 d 4.2% You are here NCD Phase Running of SNO

  27. SNO data fixes q, KamLAND fixes Dm2 Global solar data + KamLAND 766 ton-y nucl-ex/0502021

  28. NCDs break correlations between NC and CC spectra D2O Salt

  29. SAGE Measurement of the solar neutrino capture rate with gallium metal.71Ga(v, e-)71Ge, Eth = 0.233 keV Baksan Presently SAGE is the only experiment sensitive to the low-energy neutrinos It has the longest almost uninterrupted time of measurements among operating solar neutrino experiments 15 year period (Jan 1990 – Jan 2005): 135 runs, 244 separate counting sets Results: 67.2 + 3.7/ -3.7 +3.6/ -3.2 SNU or 67.2+5.2/ -4.8 SNU Yearly averages All extractions SAGE continues to perform regular solar neutrino extractions every four weeks with ~50 t of Ga

  30. GNO – Final Results exposures 58 solar runs 1713 days blanks 12 Running May 20, 1998 to April 9, 2003 GNO62.9 ± 5.5 ± 2.5SNU (L 68. ± 9. K 60. ± 7.) GALLEX 77.5 ± 6.2 +4.3-4.7 SNU GALLEX+GNO69.3 ± 5.5 SNU SAGE 9/05 67.2 +5.2-4.8 SNU Results are consistent with flux constant in time. GNO: hep-ex/0504037

  31. Bahcall et al. astro-ph/0212331: LCNO/Lsun <7.3% (3) CNO Neutrinos? Use SNO flux for 8B Use BP04 flux for 7Be Calculate pep/pp and 14N/15O Use Bahcall cross sections (PRC 56, 1997) GNO LCNO/Lsun <6.5% (3) = 0.8% BP04: 1.6 ± 0.6%

  32. Cross Sections in Solar Neutrino Physics • Still a very important problem. • Can directly affect neutrino results, even model-independent ones • Examples: • Ga neutrino cross sections • Shape of the 8B neutrino spectrum • Shape of the hep spectrum • Is there a ground-state decay from 8B? • Nuclear cross sections: 7Be(p,)8B and 4He(3He,)7Be • Radiative corrections

  33. SAGE Development of the technology of 37Ar neutrino source fabrication Baksan ■Prototype 37Ar neutrino source with strength of 409 ± 2 kCi was produced by irradiating 330 kg of CaO in the fast neutron breeder reactor BN-600 (Zarechny, Russia) 40Ca(n, α) 37Ar; Eth = 2 MeV ■ It is shown that 37Ar source with strength of 2.0 – 2.5 MCi can be produced in BN-600 reactor. ■ Several techniques for source intensity measurement were developed ■ Ten irradiations of 13 tonnes of gallium metal were made ■ No accompanying γ-rays except IB ■ No radioactive impurities ■ Little shielding thus yielding a very compact source SAGE concludes: the source experiments with Ga should be considered to be a determination of the neutrino capture cross section

  34. Ortiz et al. New Measurement of 8B n Spectrum Winter, Freedman, et al. PRL 91 252501, NP A746, 311 (2004)

  35. hep and Possible Ground-State Decay of 8B M. Bacrania et al. Univ. Washington

  36. e+ Lead 8B PiN. scint. With 8B and 12N radioactive beams … Preliminary results: Branch less than 10-4, not a concern

  37. 7Be(p,)8B astrophysical S-factor Seattle – TRIUMF collaboration S-factor Cross section • S17(0) = 22.1 ± 0.6(exp) ± 0.6(theor) eV barn Junghans et al., Phys. Rev. C68 (2003)065803 •  reduced uncertainty in accepted value of S17(0) by factor of nearly 3 (BP04). • S17(0) uncertainty is no longer important in SSM 8B neutrino flux. • BP04 SSM +  data  8B sterile  fraction  6% (1) ( 11% from  data alone) • Balantekin et al., priv. comm. [hep-ph/0405019 v1, May2004]

  38. Accomplishments, Future Plans • 12 mass splitting measured • Mixing angle precisely measured: combination of 12 and 13 • Level order fixed • MSW effect seen via energy dependence in global fits • Solar models strikingly confirmed • All 3 masses now linked by oscillations: cosmological implications, relation to tritium direct mass measurements • The low-energy spectrum below 5 MeV is known only from radiochemical experiments. What are the pp, pep, CNO, 7Be rates? • Can we make a direct test of the luminosity constraint? • Are there sterile neutrinos? Non-standard interactions?

  39. We are not yet able to count the low-energy neutrinos very precisely. • We need new experiments in this region: • Borexino • KamLAND Solar • SNO+ • LENS • CLEAN • … sin213 = 0 Barger et al. hep-ph/0501247

  40. New Physics NC non-standard Lagrangian • non-standard interactions • MSW is linear in GF and limits from n-scattering experiments  g2aren’t that restrictive • mass-varying neutrinos M. Chen, SNOLab 2005 CHARM limit Friedland, Lunardini, Peña-Garay, hep-ph/0402266 Miranda, Tórtola, Valle, hep-ph/0406280 pep solar neutrinos are at the “sweet spot” to test for new physics Barger, Huber, Marfatia, hep-ph/0502196

  41. Solar Neutrinos and 13 Fogli et al. hep-ph/9912231 Maltoni et al. hep-ph/0309130

  42. 7 Coupled Equations

  43. 5 unknowns (2004 analysis. Some of the inputs need updating) Solar can help improve 13 determination by up to a factor 2, but is not the ultimate way to determine this important parameter

  44. Borexino 100-tonne Liquid Scintillator at LNGS

  45. KamLAND Solar • $6M Distillation Facility being built. • Seems to reduce impurities to required levels. • Problem with PPO being removed.

  46. SNO+ See talk by Christine Kraus, Tuesday 16:00 • SNO plus liquid scintillator → physics program • pep and CNO low energy solar neutrinos • tests the neutrino-matter interaction, sensitive to new physics • geo-neutrinos • 240 km baseline reactor oscillation confirmation • supernova neutrinos • double beta decay?

  47. LENS (Indium): GOAL • Precision Measurement of the • Neutrino Luminosity of the Sun • LENS-Sol • Measure the low energy nu spectrum (pp, Be, CNO) • ± ~3% pp flux •  Exptl Tool: Tagged CC Neutrino Capture in Indium • νe + 115In  e- + (delay) 2 γ + 115Sn • solar signaltag • LENS-Cal • Measure precise B(GT) of 115In CC reaction using MCi 51Cr neutrino source at BAKSAN • Tagged ν-capture to specific level of 115Sn • Note: B(GT) = 0.17 measured via (p,n) reactions R.S.Raghavan/VT/Aug05

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