1. G. Sullivan - Princeton - Mar 2002 What Have We Learned from Super-K? –Before Super-K –SK-I (1996-2001) Atmospheric Solar –SNO & SK-I Active solar –SK Accident Rebuild Greg Sullivan University of Maryland

2. G. Sullivan - Princeton - Mar 2002 Why Super-Kamiokande? Solar Neutrinos “Problem” –3 experiments showed a deficit of solar neutrinos. Going back ~30 years –About ½ of the expected number were observed –results can not be reconciled with the standard solar model Atmospheric Neutrino “Anomaly” – IMB and Kamiokande saw less than expected ratio of    e One Proposed Explanation was: Neutrino Oscillations –Solar neutrinos might be e   –Atmospheric neutrinos might be   

3. G. Sullivan - Princeton - Mar 2002 Neutrino Oscillations If neutrinos oscillate then “mixing” must occur between different type of neutrinos. Weak eigenstates of the neutrino are mixtures of the neutrinos with definite mass. – mass is not 0 and flavor is not absolutely conserved! Probability of electron neutrino to remain electron flavor Matter Effects will alter this vacuum expression –MSW effect

4. G. Sullivan - Princeton - Mar 2002 Super-Kamiokande Detector  Detector Characteristics  41 m h x 39 m dia.  50,000 ton (22,000 ton fiducial)  11,200 20” PMTs inner detector  1,850 8” PMTs anti- detector  40% photo-cathode coverage

5. G. Sullivan - Princeton - Mar 2002 Super-Kamiokande

6. G. Sullivan - Princeton - Mar 2002 Detecting neutrinos Electron or muon track Cherenkov ring on the wall The pattern tells us the energy and type of particle We can easily tell muons from electrons

7. G. Sullivan - Princeton - Mar 2002 A muon going through the detector

8. G. Sullivan - Princeton - Mar 2002 A muon going through the detector

9. G. Sullivan - Princeton - Mar 2002 A muon going through the detector

10. G. Sullivan - Princeton - Mar 2002 A muon going through the detector

11. G. Sullivan - Princeton - Mar 2002 A muon going through the detector

12. G. Sullivan - Princeton - Mar 2002 A muon going through the detector

13. G. Sullivan - Princeton - Mar 2002 Stopping Muon

14. G. Sullivan - Princeton - Mar 2002 Stopping Muon – Decay Electron

15. G. Sullivan - Princeton - Mar 2002 Atmospheric Neutrino Production Ratio predicted to ~ 5% Absolute Flux Predicted to ~20% :

16. G. Sullivan - Princeton - Mar 2002 Atmospheric Oscillations about 13,000 km about 15 km Neutrinos produced in the atmosphere We look for transformations by looking at s with different distances from production SK

17. G. Sullivan - Princeton - Mar 2002 Atmospheric Neutrino Interactions Reaction Thresholds Electron: ~1.5 MeV Muon: ~110 MeV Tau: ~3500 MeV Charged Current Neutral Current e  e n p W +

18. G. Sullivan - Princeton - Mar 2002 Telling particles apart MuonElectron

19. G. Sullivan - Princeton - Mar 2002 Muon - Electron Identification PID Likelihood sub-GeV, Multi- GeV, 1-ring Monte Carlo (no oscillations) We expect about twice as many  as e

20. G. Sullivan - Princeton - Mar 2002 Super-K Atmospheric Data Set 1289.4 days of data (22.5 kilotons fiducial volume) Data Set is divided into: –Single and Multi Ring events –Electron-like and Muon-like –Energy Intervals 1.4 GeV Also E vis < 400MeV (little or no pointing) –Fully or partially contained muons (PC) –Upward going muons - stopping or through going Data is compared to Atmospheric Monte Carlo –Angle (path length through earth) –Visible energy of the Lepton

21. G. Sullivan - Princeton - Mar 2002 Low Energy Sample No Oscillations Oscillations (1.0, 2.4x10 -3 eV 2 )

22. G. Sullivan - Princeton - Mar 2002 Moderate Energy Sample

23. G. Sullivan - Princeton - Mar 2002 Multi-GeV Sample Oscillations (1.0, 2.4x10 -3 eV 2 ) No Oscillations UP going DownUPDown

24. G. Sullivan - Princeton - Mar 2002 Multi-Ring Events

25. G. Sullivan - Princeton - Mar 2002 Upward Going Muons

26. G. Sullivan - Princeton - Mar 2002 Summary of Atmospheric Results Best Fit for  to  Sin 2 2  =1.0,  M 2 =2.4 x 10 -3 eV 2  2 min =132.4/137 d.o.f. No Oscillations  2 min =316/135 d.o.f. 99% C.L. 90% C.L. 68% C.L. Best Fit Compelling evidence for  to  atmospheric neutrino oscillations

27. G. Sullivan - Princeton - Mar 2002 Tau vs Sterile Neutrino Analysis

28. G. Sullivan - Princeton - Mar 2002 Tau Appearance? Tau’s require greater than 3 GeV in neutrino energy –This eliminates most events Three correlated methods were used –All look for enhanced upward going multi-ring events All show slight evidence for Tau appearance None are statistically significant

29. G. Sullivan - Princeton - Mar 2002 The  0 sample For  to s the rate of NC events is reduced as compared to  to  which is the same as no oscillations. The SK NC enriched sample is only about 1/3 from NC interactions. The  0 sample is the cleanest NC signal Until K2K the error in  (  0 ) (~1-2 Gev) has been as large as the effect!

30. G. Sullivan - Princeton - Mar 2002  0 Peaks

31. G. Sullivan - Princeton - Mar 2002 New Results

32. G. Sullivan - Princeton - Mar 2002 Neutrinos From Solar Reactions

33. G. Sullivan - Princeton - Mar 2002 The Solar Neutrino Problem

34. G. Sullivan - Princeton - Mar 2002 Oscillation Parameter Space LMA LOW VAC SMA

35. G. Sullivan - Princeton - Mar 2002 Expected Day – Night Asymmetry Bahcall

36. G. Sullivan - Princeton - Mar 2002 Solar Neutrinos in Super-K The ratio of NC/CC cross section is ~1/6.5 W e - e e - e - Charged Current (electron ’s only)

37. G. Sullivan - Princeton - Mar 2002 Solar Neutrinos in Super-K Super-K measures: –The flux of 8 B solar neutrinos (electron type) –Energy, Angles, Day / Night rates, Seasonal variations Super-K Results: –We see the image of the sun from 1.6 km underground –We observe a lower than predicted flux of solar neutrinos (45%)

38. G. Sullivan - Princeton - Mar 2002 Low Energy Electron in SK

39. G. Sullivan - Princeton - Mar 2002 Solar Neutrinos From Sun Toward Sun SSM: Bachall 2000 Flux: 8 B 5.05x10 6 /cm 2 /s Spectrum Ortiz et al

40. G. Sullivan - Princeton - Mar 2002 Global Flux allowed parameter space

41. G. Sullivan - Princeton - Mar 2002 Energy Spectrum

42. G. Sullivan - Princeton - Mar 2002 Energy Spectrum

43. G. Sullivan - Princeton - Mar 2002 Day / Night - BP2000+New 8 B Spectrum Preliminary

44. G. Sullivan - Princeton - Mar 2002 Seasonal Variation

45. G. Sullivan - Princeton - Mar 2002 Combined Results

47. G. Sullivan - Princeton - Mar 2002 SNO Results - Summer 2001 SNO measures just e SK measures mostly e but also other flavors (~1/6 strength) From the difference we see oscillations! } This is from  &  neutral current

48. G. Sullivan - Princeton - Mar 2002 Combining SK and SNO SNO measures  e = (35 ± 3 )%  ssm SK Measures  es = (47 ±.5 ± 1.6)%  ssm No Oscillation to active neutrinos: –~3  difference If Oscillation to active neutrinos: –SNO Measures just  e This implies that    ssm (~2/3 have oscillated) –SK measures  es =(  e + (    /6.5) Assuming osc. SNO predicts that SK will see  es ~ (35%+ 65%/6.5)  ssm = 45% ± 3%  ssm

49. G. Sullivan - Princeton - Mar 2002 SK & SNO Flux Measurements

50. G. Sullivan - Princeton - Mar 2002 Super-K Repairs in Summer 2001

51. G. Sullivan - Princeton - Mar 2002 Super-K Disaster - Nov 12, 2001 Chain reaction destroyed 7000 ID and 1000 OD Tubes The cause is not completely understood, but it started with a bottom pmt collapse. The energy release comes from a 4 T column of water falling There are plans to rebuild…

52. G. Sullivan - Princeton - Mar 2002 Disaster (Continued)

53. G. Sullivan - Princeton - Mar 2002 Disaster (Continued)

54. G. Sullivan - Princeton - Mar 2002 Disaster (Continued)

55. G. Sullivan - Princeton - Mar 2002 Rebuild at ½ of Original Coverage

56. G. Sullivan - Princeton - Mar 2002 What Have We Learned? Neutrinos undergo flavor oscillations –Neutrinos have mass –Flavor mixing 3 mixing angles, 2  m 2 & 1 mass (or 3 masses) Atmospheric –Maximal mixing (   ) –  m 23 2 ~ 2 x 10 -3 eV 2 Solar –Looks like active not sterile neutrinos –  m 12 2 ~ ? –   Mixing angle ?

57. G. Sullivan - Princeton - Mar 2002 What We’ll Hopefully Know Soon Kamland, Borexino,SNO,SK,Cl,Ga –Which solution for solar neutrinos first  m 12 2 first   Accelerator (MINOS, JHF, K2K,…) –Better  m 23 2, better   –First measurement of   If    not zero –CP Violation in neutrinos possible

58. G. Sullivan - Princeton - Mar 2002 Questions Neutrino Mass –Majorana or Dirac? Lepton Number Violation? GUTs? –What is the absolute Mass Scale? Why neutrinos have such small mass? Which mass Hierarchy of 3 mass states? Cosmology? Mixing Matrix –Why mixing structure different then CKM in quarks? GUTs? –CP Violation?