1 Evidence of Neutrino Oscillation from Super-Kamiokande and K2K Neutrino physics at Super-Kamiokande –Detector overview –Atmospheric neutrinos –Solar neutrinos –Neutrinos from supernova and gamma-ray burst Long baseline K2K neutrino experiment –Near detector and neutrino source –Results from K2K Future Plans Jen-Chieh Peng Workshop on Neutrino Physics, November 28-29, Hong Kong University of Illinois

2 Super-Kamiokande Water Cherenkov Detector BaBar: Belle: 1000 meters underground 41 meters high and 39 meters in diameter 50,000 tonnes of water 11, inch photomultiplier tubes Measure Cherenkov rings produced by e ± and μ ± e/μ separation based on characteristics of the Cherenkov ring Energy of e/μ determined from ring radius

3 Atmospheric Neutrinos R = 0.63 ± 0.03 ± 0.05 (sub-GeV e,μ) R = 0.65 ± 0.05 ± 0.08 (multi-GeV e,μ) Result from Super-Kamiokande: R = 1 if no oscillation

4 Zenith Angle Dependence (Y. Hayato, HEP2003 talk) Blue: no oscillation Red: sin 2 2θ = 1.0, Δm 2 = 2.5 x ev 2 (Predictions for sin 2 2θ = 1.0, Δm 2 = 2.5 x ev 2 ) L changes with zenith angle

5 (hep-ex/ ) Tau-enriched sample Black: no oscillation Red:

6 Mixing angles and Δm 2 3-flavor oscillation analysis from SK sets limit on sin 2 θ 13 Best-fit values: sin 2 2θ a = 1.0; Δm a 2 = 2.0 x ev 2

7 Solar Neutrino Measurement at Super-Kamiokande Advantages: Energy information Time information Directionality Disadvantages: Sensitive to higher energy neutrinos (from 8B) Limited energy resolution

8 Solar Neutrino Measurement at Super-Kamiokande Angle between electron direction and sun-earth direction Variation of sun-earth distance

9 Solar Neutrino Measurement at Super-Kamiokande An overall flux suppression with weak energy dependence

10 Solar Neutrino Measurement at Super-Kamiokande

11 Time-Dependence of Solar Neutrino Flux Data from 37 Cl experiment Data from Super-Kamiokande (hep-ex/ )

12 Search for Anti-neutrinos from the Sun How can be produced in the Sun? Spin-flavor precession Majorana neutrino Non-zero neutrino magnetic moment Large magnetic field in the Sun

13 Search for Neutrinos from Other Astrophysical Sources Gamma Ray Bursts (GRB) Search for neutrinos correlated with 1371 GRBs observed by BATSE

14 Search for Neutrinos from Other Astrophysical Sources Supernova Relic Neutrinos (SRN) SN1987A observed at Kamiokande Upper limit of 20 to 130 cm -2 s -1 Exclude certain SRN model

15 K2K Long-Baseline Neutrino Oscillation Experiment To check atmospheric neutrino result from Super-Kamiokande using accelerator neutrino source

16 K2K Long-Baseline Neutrino Oscillation Experiment Measured neutrino spectrum

17 K2K Long-Baseline Neutrino Oscillation Experiment Angular and momentum distribution of muons measured at the near K2K detector

18 K2K Long-Baseline Neutrino Oscillation Experiment Black: no oscillation Red: with oscillation K2K result is consistent with SK. More data are being taken

19 JHF-SuperKamiokande Neutrino Oscillation Experiment A major goal is to determine θ 13

20 Hyper-Kamiokande Detector ? 1 mega-ton detector consisting of 14 sub-detector (70 kilo-ton each)

21 Summary Evidence for neutrino oscillation is observed from the zenith angle dependence of atmospheric neutrino signals measured at Super-Kamiokande. Preliminary results from K2K experiment are consistent with the atmospheric neutrino oscillation result from Super-Kamiokande. More data are forthcoming. Super-Kamiokande data provide some constraints on the magnitude of θ 13. Future experiment (JHF- SuperKamiokande) has been proposed to measure θ 13 with improved sensitivity. Other experiments sensitive to θ 13 are clearly of interest. Neutrino experiments address some of the most important mysteries in particle and astrophysics, as demonstrated by the extremely successful Super-Kamiokande experiment