What we know from Solar Neutrinos The next steps Low-energy solar neutrinos

Transcription

1 Hamish Robertson, University of Washington WIN 02, Christchurch NZ Jan. 22, 02 1 A Place in the Sun for Neutrinos Experimental inputs: Rates from 7 experiments Shape, D/N from Super-Kamiokande The SNO experiment What we know from Solar Neutrinos The next steps Low-energy solar neutrinos Physics goals Experiments

2 2 Some other Solar Neutrino Talks at WIN 02 Thursday 11:30 Colin Okada What else can SNO do? 2:00 Junpai Shirai KamLAND 2:40 Till Kirsten Aims and Status of Borexino Friday 6:45 Tom Bowles Low Energy Neutrino Spectroscopy (LENS)

3 3 Cl-Ar at Homestake e + 37 Cl 37 Ar + e -

4 4 Cl - Ar Results

5 5 The SAGE Experiment V. Gavrin et al. NP (B)91, 36, e + 71 Ga 71 Ga + e - Combined L and K data SNU

6 6 The GNO and Gallex Experiments M. Altmann et al. hep-ex/ e + 71 Ga 71 Ga + e - Combined Gallex+ GNO 74.1(68) SNU

7 7 If your experiment needs better statistics, you need a better experiment. Lord Rutherford

8 The Super-Kamiokande Light-Water Cherenkov Detector 8

9 9 Super-Kamiokande May 31, July 1, live days E 6.5 MeV (361 d) E 5.5 MeV (756 d) E 5.0 MeV at end 8 = cm -2 s -1

10 Energy spectrum Data/SSM SK-I 1496day MeV 22.5kt (Preliminary) (flat)=17.40 (50%) d/n spec best fit (0.55, 4.5x10-10 ) LMA minimum (0.76, 2.2x10-5 ) LOW minimum (0.95, 9.5x10-8 ) Energy(MeV) 10

11 Rate measurements (BP2000.2) Totsuka Homestake 37 Cl 0.34±0.03 SAGE 71 Ga 0.59±0.06 GALLEX+GNO 71 Ga 0.58±0.05 Super-K e - (water) 0.465±0.016* SNO d (D2O) 0.347±0.029 * for BP2000_old SNU SNU 2.56 ± ± ± ± ±7 37 SuperK H 2 O Kamioka Cl Ho D 2 O mestake 7 Be pp, pep Experiments Theory 8 B CNO SNO SAGE Ga GAL LEX ( +GNO)

12 12 Reactions in Heavy Water CC e d p p - e - Charged Current - e only. NC d p n x x - Neutral Current - Equal cross section for all active types e - e ES - x x - Elastic Scattering -Mainly sensitive to e,, some sensitivity to and

13 13 Reactions in SNO CC e d p p - e -Gives e energy spectrum well -Weak direction sensitivity 1-1/3cos( ) - e only. NC d p n x x -Measure total 8 B flux from the sun. - Equal cross section for all types e - e ES - x -Low Statistics -Mainly sensitive to e,, some -sensitivity to and -Strong direction sensitivity x

14 14 SNO First results from the Sudbury Neutrino Observatory, and their Implications nucl-ex/ v2 J. Farine

15 Aurora Australis 15

16 16 Sudbury Neutrino Observatory 1000 tonnes D 2 O Support Structure for 9500 PMTs, 60% coverage 12 m Diameter Acrylic Vessel 1700 tonnes Inner Shielding H 2 O 5300 tonnes Outer Shield H 2 O Urylon Liner and Radon Seal

17 17 SNO Collaboration S. Gil, J. Heise, R. Helmer, R.J. Komar, T. Kutter, C.W. Nally, H.S. Ng,Y. Tserkovnyak, C.E. Waltham. University of British Columbia J. Boger, R. L Hahn, J.K. Rowley, M. Yeh Brookhaven National Laboratory I. Blevis, F. Dalnoki-Veress, W. Davidson, J. Farine, D.R. Grant, C. K. Hargrove, I. Levine, K. McFarlane, C. Mifflin, T. Noble, V.M. Novikov, M. O'Neill, M. Shatkay, D. Sinclair, N. Starinsky Carleton University T.C. Andersen, M.C. Chon, P. Jagam, J. Law, I.T. Lawson, R. W. Ollerhead, J. J. Simpson, N. Tagg, J.X. Wang University of Guelph R.G. Allen, G. Buhler, H.H. Chen* University of California, Irvine J. Bigu, J.H.M. Cowan, E. D. Hallman, R.U. Haq, J. Hewett, J.G. Hykawy, G. Jonkmans, A. Roberge, E. Saettler, M.H. Schwendener, H. Seifert, R. Tafirout, C. J. Virtue. Laurentian University Y. D. Chan, X. Chen, M. C. P. Isaac, K. T. Lesko, A. D. Marino, E. B. Norman, C. E. Okada, A. W. P. Poon, A. R. Smith, A. Schülke, R. G. Stokstad. Lawrence Berkeley National Laboratory T. J. Bowles, S. J. Brice, M. Dragowsky, M.M. Fowler, A. Goldschmidt, A. Hamer, A. Hime, K. Kirch, G.G. Miller, J.B. Wilhelmy, J.M. Wouters. Los Alamos National Laboratory J.C. Barton, S.Biller, R. Black, R. Boardman, M. Bowler, J. Cameron, B. Cleveland, X. Dai, G. Doucas, J. Dunmore, H. Fergani, A.P. Ferraris, K.Frame, H. Heron, C. Howard, N.A. Jelley, A.B. Knox, M. Lay, W. Locke, J. Lyon, S. Majerus, N. McCaulay, G. McGregor, M. Moorhead, M. Omori, N.W. Tanner, R. Taplin, M. Thorman, P. Thornewell. P.T. Trent, D.L.Wark, N. West, J. Wilson University of Oxford E. W. Beier, D. F. Cowen, E. D. Frank, W. Frati, W.J. Heintzelman, P.T. Keener, J. R. Klein, C.C.M. Kyba, D. S. McDonald, M.S.Neubauer, F.M. Newcomer, S. Oser, V. Rusu, R. Van Berg, R.G. Van de Water, P. Wittich. University of Pennsylvania E. Bonvin, M.G. Boulay, M. Chen, F.A. Duncan, E.D. Earle, H.C. Evans, G.T. Ewan, R.J. Ford, A.L. Hallin, P.J. Harvey, J.D. Hepburn, C. Jillings, H.W. Lee, J.R. Leslie, H.B. Mak, A.B. McDonald, W. McLatchie, B. Moffat, B.C. Robertson, P. Skensved, B. Sur. Queen's University Q.R. Ahmad, M.C. Browne, T.V. Bullard, T.H. Burritt, P.J. Doe, C.A. Duba, S.R. Elliott, R. Fardon, J.V. Germani, A.A. Hamian, R. Hazama, K.M. Heeger, M. Howe, R. Meijer Drees, J.L. Orrell, R.G.H. Robertson, K. Schaffer, M.W.E. Smith, T.D. Steiger, J.F. Wilkerson. University of Washington

18 The SNO Detector during Construction 18

19 Heavy Water from Bruce Plant 19

20 Signals in SNO 20

21 21 Looking for unexpected Neutrino Flavors Measure total flux of solar neutrinos vs. the pure e flux Charged-Current to Neutral Current ratio is a direct signature for oscillations CC NC e e CC/ES Could also show significant effects CC ES e e 0.15( ) Smoking Guns for Neutrino Oscillations

22 22 Instrumental backgrounds Note Neck Tubes Fired Electronic Pickup

23 23 Application of Instrumental Background Cuts Data Period: Nov 2, 1999 Jan 15, 2001 Live Time: days Analysis Step Events Total Event Triggers 355,320,964 Neutrino Data Triggers 143,756,178 Nhit 30 6,372,899 Instrumental Background 1,842,491 Muon Followers 1,809,979 High Level Cuts 956,535 Fiducial Volume Cut 18,783 Threshold Cut,T eff 6.75 MeV 1169 Total Events In Final Data Set 1169 High Level Cuts: Reconstruction figures of merit In-time light Event isotropy ( ij )

24 24 SNO Energy Calibrations 252 Cf neutrons s from 8 Li s from 16 N and t(p, ) 4 He

25 25

26 26

27 27 Direction of Events with respect to the Sun Elastic Scattering Events/0.1 bin Charged Current ~(1-1/3 cos ) 20 Neutrons - flat, ~10% cos sun

28 28 Neutrino Flavor Composition of 8 B Flux Fluxes (10 6 cm -2 s -1 ) e : 1.75(15) : 3.69(113) total : 5.44(99) SSM : 5.05 SK CC = e ES = e ,

29 29 Charged Current Energy Spectrum Data/BPB01 ( 8 B only) Super-K ES flux CC spectrum normalized to predicted 8 B spectrum. no evidence for shape distortion Kinetic energy (MeV)

30 30 New Measurement of 7 Be(p, ) 8 B Junghans et al. nucl-ex/ (10 6 cm -2 s -1 ) 1998 : : Bahcall et al. hep-ph/ S(0) (kev b) 1998: :

31 31 Neutrino Oscillations Fogli et al. hep-ph/ B Flux (New 8 B) P ee ( e survival)

32 32 Charged Current and Elastic Scattering Fluxes Absolute Fluxes: ( Units 10 6 cm -2 s -1 ) CC ( 8 B) = 1.75 ± 0.07 ± 0.05 ES ( 8 B) = 2.39 ± 0.34 (stat) (sys.) (theor) (stat) (sys.) Super-Kamiokande finds ES ( 8 B) = 2.32 ± 0.03 CC 1.0 CC ES (stat) (sys.) (S. Fukuda, et al., hep-ex/ ) - ES = (3.3 )

33 33 Experimental Systematic Errors Error Source CC Error (%) ES Error (%) Energy Scale +6.1/ /-3.5 Energy Resolution Energy Scale Non-Linearity Vertex Shift Vertex Resolution Angular Resolution Live Time Trigger Efficiency Cut Acceptance +0.7/ /-0.6 Earth orbit eccentricity O, 18 O Residual Backgrounds (R fit 550 cm) Instrumental Background -0.2/ /+0.0 High Energy s -0.3/ /+0/0 Low Energy Background Experimental Uncertainty +7.0/ /-5.7 Cross Section

34 34 Radiative and other corrections CC (and NC) cross sections calculated with BCK Effective Field Theory. Counterterm L 1,A obtained by normalizing to NSGK Potential Model Radiative corrections not made, except for updates to g A Calculation g A Ref NSGK Nakamura et al. PR C , BCK 1.26 Butler, Chen & Kwong, PR C SNO Beacom & Parke hep-ph/ New, consistent treatment of radiative corrections by Kurylov, Ramsey-Musolf, and Vogel (nucl-th/ ): Total cross section increases by 3-4%. Threshold for soft s in SNO reduces this to 2%

35 35 SNO Conclusions Evidence that e produced in the Sun are transformed to and/or -- solar neutrinos having a flavor other than electron are being detected on Earth First measurement of the total flux of 8 B neutrinos: total ( 8 B) = 5.44 ± 0.99 x10 6 cm -2 s -1 Agrees well with solar models: SSMl ( 8 B) = 5.05 ± 0.80 x10 6 cm -2 s -1 (BPB01) Neutrino models with mixing solely to a sterile neutrino are not compatible with these data, but small additional sterile oscillation channel possible

36 Allowed Solutions for 2-Neutrino Oscillations (Before) Fogli et al. hep-ph/ ; Bahcall et al. hep-ph/ To Active Neutrinos To Sterile Neutrinos

37 37 SNO Allowed Solutions for 2-Neutrino Oscillations To Active Neutrinos To Sterile Neutrinos

38 Krastev & Smirnov hep-ph/ Aug.22, 2001

39 s e e H. Murayama

40

41 41 A viable mass spectrum s LSND Mass (ev) ~1 5 5 Percentages e mu tau 3 Atmospheric Solar =

42 42 Mass eigenstate expansion e Solar neutrino oscillations introduce a 50:50 admixture of and into the originally pure e state. All solar solutions matter-enhanced: we now know level order 1,2

43 43 Cosmological Implications SNO + CHOOZ: m 12 -m 22 < 10-3 ev 2 Limits on e mass: U e1 2 m 12 + U e2 2 m 2 2 < (2.8) 2 ev 2 oscillations in atmospheric neutrinos: m 22 -m ev 2 neutrino masses: 0.05 < m < 8.4 ev 123 limit on fraction of universe closure density: < < 0.18

44 44 The next steps... What are the values of m 2,U ij? What is the level ordering? What are the masses? Is U e3 = 0? How big is CP violation for neutrinos? Is U 3-dimensional? 4? 6?? or, is the 3-D version unitary? Do neutrinos and antineutrinos mix?

45 Maris & Petcov 02 Bandyopadhyai et al. 01: On tan 2 scale!

46 46 Signals in SNO NC Salt (BP98)

47 Time dependence of energy calibration 47

48 D/N Asymmetry for Super-Kamiokande Maris & Petcov 02 Bandyopadhyai et al. 01

49 Data/SSM Day/night variation SK-I 1496day MeV 22.5kt (Preliminary) Z SK Day N1 N2 N3 core 0.45 mantle N4 N5 0.4 LMA d/n minimum (0.78, 7.6x10-5 ) LMA flux minimum (0.76, 2.2x10-5 ) LOW flux minimum (0.95, 9.5x10-8 ) Day Night 0.35 All Day Night cosθ z Day(733 days): 2.32± Night(763 days): 2.37±0.03±0.08 (N-D)/((N+D)/2): 0.021±

50 Maris & Petcov 02 Bandyopadhyai et al. 01

51 Day-night exposure at SNO 51

52 52 Day-night exposure... Nadir Zenith

53 53 Borexino & KamLAND Distinguishing LMA and LOW is difficult at present. Borexino should see a large D/N asymmetry if it s LOW KamLAND should have a clear signal from reactor e disappearance if it s LMA Lisi et al., PRD , (2000)

54 KamLAND Kamioka Liquid scintillator Anti-Neutrino Detector 1000m 3 liquid scintillator 3000m 3 oil+water shield inch PMTs inch PMTs Anti- e from reactors (L~170km) Detect e + from e + p e + + n (Eth = 1.8 MeV) 54

55 First KamLAND Event November, 01 55

56 56 Borexino ton liquid scintillator (100 ton fid.vol) in PMTs Ee > 250keV e + e e + e 55 ev/day for SSM

57 57 Unitarity of MNSP Matrix Are there sterile neutrinos? What is the dimensionality of U? Disappearance experiments over long baselines required Let U = U atm U e3 U solar MiniBOONE will test whether a sterile component is present at 1eV 2 SNO, K2K, MINOS NC will normalize U atm Low-energy solar neutrinos can test unitarity for U e3 U solar pp flux now known to ~1% very long baseline, small m 2 High precision CC and ES (or NC) required: e.g. LSND in a 3+1 gives ~5% e flavor in a sterile. Active oscillations complicate pp spectrum

58 58 Solar Neutrino Experiments Fiduc ial Mas s Thres ho ld, ke V BP0 0 Rat e s pe r ye ar Exp t. Type Ton s of ES CC NC pp +p e p So lar Ne ut rino Exp e rime nt s 7 Be 8 B CNO Eve nt Eff. % Cl-A r Radioch Cl Kam ioka Cerenk ov 680 water SAGE Radioch Ga Gallex Radioch Ga Su p e rk Cerenk ov water GNO Radioch Ga SNO Cerenk ov 2000 water H H St art Kam LAND Sc int illator 1000 scint illator 2001 Bor ex ino Sc int illator 100 scintillator HERON L He ro ton s, 5 He Sc int illator TPC Gas TPC 7 He CLEAN Sc int illator 12.5 Ne XMASS Sc int illator Xe LENS Sc int illator Yb 301, MOON Sc int illator Mo Cl Hyb rid Cl GaAs Ioniza t ion 71 Ga LiF Bolome t e r Li

59 59 Solar Neutrino Program Comm. SNO D 2 O Salt D 2 O 3 He Counters D 2 O Return? SK Cl-Ar SAGE, GNO CC, ES CC, NC, D/N CC, NC, D/N KamLAND & KamLAND Solar Borexino New Low-Energy Detectors