1 / 34

Future solar neutrino projects

Neutrino Champagne, Oct.19, 2009. M.Nakahata. Kamioka observatory, ICRR, Univ. of Tokyo. Future solar neutrino projects. Value for neutrino oscillations Value for astrophysics Current status of future solar neutrino projects Conclusions.

galya
Download Presentation

Future solar neutrino projects

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neutrino Champagne, Oct.19, 2009 M.Nakahata Kamioka observatory, ICRR, Univ. of Tokyo Future solar neutrino projects Value for neutrino oscillations Value for astrophysics Current status of future solar neutrino projects Conclusions Thanks to M.Chen, D.McKinsey, G.Ranucci, R.Raghavan, G.Ranucci, T.Lasserre, K.Inoue, H.Ejiri, S.Petcov, A.Kopylov, R.E.Lanou, M.Smy, Y.Takeuchi, B.Yang, M.Ikeda, Y.Koshio for information and discussion

  2. Solar global and KamLAND reactor SNO collaboration: arXiv:0910.2984 Solar global KamLAND Do we fully understand solar neutrino oscillation? What future solar neutrino experiments can improve (or find something new) in solar neutrino oscillation?

  3. Energy dependence of the survival probability Vacuum osc. dominant P=1 - 0.5・sin22q P(ne ne) matter osc. P=sin2q (MeV) SSM spectrum pp 7Be pep 13N 15O 8B 17F

  4. Current status of 8B spectrum measurement SNO CC (LETA) Dm2=7.2x10-5eV2, tan2q=0.38 Dm2=6.3x10-5eV2, tan2q=0.55 c2=21.52/15d.o.f. for flat = 22.56/15d.o.f. for LMA SK-I systematic error 4.5 9.5 Ekin(MeV) Borexino unoscillated MC 246 days 100tons Data/SSM Oscillated MC

  5. Nonstandard models to predict flat spectrum Sterile neutrino MaVaN Miranda, Tortola and Valle, JHEP 0610:008,2006. (hep-ph/0406280) Non standard Interaction Barger, Huber and Marfatia, Phys.Rev.Lett.95:211802,2005 (hep-ph/0502196) Holanda and Smirnov, Phys.Rev.D69(2004)113002. (hep-ph/0307266) Gonzalez-Garcia,Holanda,Zukanovich ,Funchal, JCAP 0806:019,2008. (hep-ph/0803.1180) Unparticle Friedland, Lunardini, Pena-Garay PLB594(2004)347(hep-ph/0402266)

  6. 8B day/night asymmetry Expected D/N asymmetry Current status Summary of ADN (D-N) / 0.5(D+N) Solar global (95%CL) Solar+KamLAND ES CC This is for Electron Scattering (ES). Expected Day/Night of CC is about 1.5 x ES Day/night asymmetry is 1~5% level for the solar global solution. ~1.5% for the solar+KamLAND solution.

  7. Sensitivity of Megaton Water Cherenkov detector Estimated based on SK signal/noise ratio 8B spectrum distortion Day/Night Asymmetry Correlated sys. error of SK (energy scale error : 0.64%) ADN= -1.5% ±0.3%(stat.) ± ??(sys.) with 5 Mton·years (sin2q=0.31, Dm2 =7.6×10-5 eV2) 1/2 of SK Data/SSM 5 Mton·years sin2q=0.28, Dm2 =8.3×10-5 eV2 Ee (MeV) Hepneutrino measurement Integral spectrum 5 Mton·years Assuming ±0.4%(sys.), error of Dm2 is ±~17%(1s).

  8. Event rate: (/5years/10tonXe, 8.3tonNe, 7.2ton liq. Scint.) pp: 116467Be: 6257 pep: 352 CNO: 651 8B: 66 (assuming 50keV threshold, BPS08(GS), tan2q=0.467, Dm2=7.59×10-5 eV2) Expected energy spectrum of n-e scattering With oscillation (Above 7Be energy:pep: 158 CNO: 119 )

  9. Sensitivity of mixing angle by pp experiments 10 ton (Xe) detector ne scattering experiment 5 years data Statistical error(~1%) + SSM flux error (1%) 68% CL 95% CL Value of q13 is needed for precise determination of q12. Current error size (68% C.L.) From the SNO LETA paper

  10. Sensitivity of mixing angle by pp experiments Future: with reactor q13 experiments 68% CL 95% CL 1s error (assuming Dm223=2.3x10-3 eV2) Double CHOOZ value from T.Lasserre

  11. Value of future solar neutrino experiments for astrophysics

  12. Solar neutrino spectrum from standard solar model Measured by Borexino Spectroscopic measurement by Kamiokande, Super-K, SNO, Borexino 8B n is only 0.01% of all solar neutrinos. 7Be n is 8% of all solar neutrinos. Majority of solar neutrinos, especially pp n, are not measured yet. Measurement of various neutrinos, especially CNO n, is important for astrophysics.

  13. Why do solar neutrino experiments below 1-MeV?J.N.Bahcall Proceedings of LOWNU 2000, 172-176, e-Print: hep-ex/0106086

  14. A problem in standard solar model BPS08: Neutrino fluxes and uncertainties Difference • Two solar abundances: • GS98 vs AGS05 • Z/X = 0.0229 0.0165 • Especially, C,N,O,Ne,Mg are • 30~50% reduced in AGS05 +1.2% +2.8% +4.1% -10% -21% -34% -31% -44% • In units of 1010(pp), 109(7Be), 108(pep, 13N, 15O), 106(8B, 17F), 103 hep cm-2s-1 • C. Pena-Garay and A.M.Serenelli, arXiv:0811.2424

  15. AGS05:Inconsistent with helioseismology… Sound speed Density dc/c Dr/r R/Rsun R/Rsun Boundary of convection zone Surface helium mass fraction

  16. (Serenelli et al.,astro-ph/0909.2668 ) Released on Oct.7, 2009 Revised Solar model AGSS09 vs. GS98 AGSS09 Sound speed 6.03 1.44 8.18 4.64 4.85 2.07 1.47 3.48 +1.0% +2.1% +3.5% -8.5% -18% -28% -32% -40% AGS05 dc/c AGSS09 GS98 Density AGS05 Dr/r AGSS09 GS98 AGSS09 R/Rsun 0.724 0.231 AGSS09 slightly improved the disagreement. But, still it does not yet reproduce heliosismology, RCZ and YS.

  17. What is Standard Solar model • Solve evolution from zero age along the main sequence • Using equations of hydrostatic equilibrium, mass continuity, energy conservation, energy transformation (either by convection or radiation), and equation of state • Input parameters of nuclear fusion cross section (S factor) and etc. • Boundary conditions • Current mass, radius, luminosity, age of the sun • Assumptions • Sun was chemically homogeneous at Time=0. • Initial abundances of heavy elementｓ (i.e. other than H and He) are same as current surface abundance or meteorite. Are the assumptions correct? For example, Haxton proposed that metal depletion during planet formation. It might have lowered metal content in the solar photosphere, but keeping higher metal content in the core.(arXiv:0809.3342 [astro-ph] ) It is important to look at solar core using solar neutrinos.

  18. 8B – 7Be flux correlation GS98 abundance 7Be flux AGS05 abundance With SNO LETA 8B flux • C.Pena-Garay, PHYSSUN workshop at Gran Sasso Oct.16-17, 2008

  19. N13 flux vs. 8B (made by M.Chen et al.) • Preliminary Measure CNO flux (to ±10%) and compare with solar models to differentiate high-Z / low-Z core metallicity • M. Chen, SNOLAB workshop, Aug.2009

  20. Future/Proposed solar n experiments Current

  21. XMASS Under construction ~1m ~2.5m ~30cm 800kg detector (FV 100kg) Dark matter ~20 ton detector (FV 10ton) pp, 7Be solar neutrinos Dark matter Double beta decay Prototype detector (FV 3kg) R&D Confirmation of feasibility of the ~1ton detector finished

  22. XMASS 800kg detector Water tank for cosmic ray veto, Shield gamma and neutrons 800 kg liquid Xe Viewed by 640 2-inch PMTs 神岡坑内 １５ｍ ２０ｍ Hall C at Kamioka

  23. Hall C at Kamioka 700L liquid Xe reservoir Gas Xe reservoir Distillation tower (remove Kr with 6kgXe/hour) 10mfx10mh water tank

  24. Preparation for XMASS 800kg detector Hmamatsu/XMASSproduct PMT support structure under construction. (ready by middle of November) Low background PMT 　Ｕ: ～１．４ｍＢｑ／ＰＭＴ 　Ｔｈ:～１．９ｍＢｑ／ＰＭＴ Mass production of all PMTs was finished. Construction by the end of 2009. Data taking will start early next year.

  25. CLEAN Science: WIMP dark matter pp solar neutrinos Supernova neutrinos (coherent) Schedule: 2010-2012: engineering of CLEAN 2012-2015: Detector construction 2015-2019: Liquid argon operation 2020-2024: Liquid neon operation R&D progress: • Charcoal work well to remove impurities in neon • Neon light yield is ~30,000 ptohons/MeV (comparable to other noble liquids. ~6 p.e./keV in the full size CLEAN) Compton edge of 511 keV gamma (measured by 3.14 liter MicroCLEAN) from D.McKinsey

  26. from D.McKinsey

  27. SNO+ 1000 ton liquid scintillator at 6000 m.w.e. underground Science: Double beta decay using Nd pep and CNO solar neutrinos Geo neutrinos Reactor neutrinos Supernova neutrinos Supernova neutrinos (coherent) SNO+ Budget approved in June 2009. Schedule: 2009-2010: Construction of hold-down net 2009-2010: Scintillator process and purification install. Early 2011: Ready for filling liquid scintillator. 2011: Commissioning and data taking Information from M.Chen

  28. SNO+ pepand CNO Solar Neutrino Signals CNO extracted with ±6% uncertainty (assuming target background levels 210Bi and 210Po, U, Th, 40K achieved) in three years 3600 pep events/(kton·year), for electron recoils >0.8 MeV pep neutrino measurement uncertainty ~ 4.5% from M.Chen

  29. Borexino for CNO and pep Spherical cut around2.2 gamma to reject 11C event Cylindrical cut Around muon-track Best estimate for cosmogenic 11C is 25 cpd/100 tons (1.1 mm-2h-1, <Em>325 GeV) CNO:≈ 5 cpd/100 tons pep:≈ 2 cpd/100 tons Expected from SSM with oscil. m+12C-->11C+n+m 11B+e++ne Muon track n capture g (2.2 MeV) Neutron production Borexino Coll.:Phys.Rev.C74,045805(2006)

  30. Charged Current(CC) experiment: ne flux measurement Necessity of both ES and CC experiments ne scattering(ES) experiment: ne + a(nm + nt)flux measurement a=0.30 for pp neutrino a=0.21 for 7Be neutrino compare nm+nt a(nm+nt) ne ne ne ne CC exp. ES exp. Total flux (exp.) Both of ES and CC experiments are necessary, if we want to measure total flux without relying on oscillation parameters obtained by other experiments. SSM prediction

  31. LENS Tag Delayed coincidence Time Spectrum Signal area Bgd S/N = 1 S/N = 3 Coincidence delay time μs Fitted Solar Nu Spectrum (Signal+Bgd) /5 yr/10 t In pp S/N=3 SIMULATION 7Be • LENS Signal • [SSM(low CNO) + LMA • xDetection Efficiency e] • pp:e=64%;7Be ^others:e >85% • Rate: pp 40 /y /t In • 2000 pp ev. / 5y ±2.5% • Design Goal: S/N ≥ 3 Indium Bgd CNO pep ;;; 7Be* Signal electron energy (= Eν – Q) (MeV) Access to pp spectral Shapefor the first time From Raghavan

  32. New Detector Technology –hi event position localization The Scintillation Lattice Chamber Test of double foil mirror in liq. @~2bar Light channeling in 3-d totally Internally reflecting cubic Lattice GEANT4 sim. of concept. Demonstration Acrylic Model 3D Digital Localizabilityof Hit within one cube  ~75mm precision vs. 600 mm (±2σ) by TOF in longitudinal modules  x8 less vertex vol.  x8 less random coinc.  Big effect on Background  Hit localizability independent of event energy From R.Raghavan

  33. Final Test detector for LENS-Under Construction in KURF MINILENS • Goals for MINILENS • 8kg In; 400 liter InLS-9x9x9 cell • In scintillation lattice • Test detector technology •  Medium Scale InLS production •  Design and construction • Test background suppression of In • radiations by 10-11 •  Expect ~ 5 kHz In -decay singles • rate; adequate to test trigger • design, DAQ, and background • suppression schemes • Demonstrate In solar signal detection in the presence of high background (via “proxy”) • Direct blueprint for full scale LENS

  34. Conclusions • We should make more efforts to improve our understanding of solar neutrino oscillations, especially, matter effect. • So far, spectroscopic measurement was done only for 8B and 7Be neutrinos. Measurement of other solar neutrinos(especially, pp n) are important for astrophysics. • SSM with improved metal abundance does not agree with helioseismology. • Neutrino flux measurements of CNO, 7Be and 8B are important to investigate metal abundance in the core. • Status and R&D of the future solar neutrino experiments were presented.

More Related