These 20 Years M. Koshiba The University of Tokyo

1. These 20 YearsM. KoshibaThe University of Tokyo Almost 20 years ago here in Venice and in the same International Workshop on Neutrino Telescopes I delivered a talk entitled “Imaging Water Cherenkov Detector; Why and How” 1) . In its introduction I said “the use of this technique for exploiting this new-born science of n-astrophysics constitutes a very promising future”. Furthermore, in the section of “What is next and how?” I listed as the physics problems to be considered; 1) solar 8B n`s with better statistics and resolution, 2) future supernova n`s, 3) dark matter search with the sun as their reservoir, 4) n-oscillation, and 5) high energy n point sources. To deal with these problems I proposed installing Super KAMIOKANDE of 32,000tons fiducial water mass; Fig.9 of ref.1). KAMIOKANDE played the role of feasibility experiment beautifully and was closed in April of 1996. Super KAMIOKANDE was started building April 1, 1996. In November of 2001there was an unfortunate accident in which more than 5, 000PMTs were destroyed but it was completely recovered in July,2006. See the next slide.The 3rd generation experiment at KAMIOKA called KamLAND was also installed and has been working on anti-ne, but this will be described by its creator, Prof. A. Suzuki,later in the session. .

2. 1988 Just a drawing 2008 Real observatory in operation (Photo just after the full reconstruction in 2006) Fig.9 of Ref.1)

3. 1) solar 8B n`s with better statistics and resolution • KAMIOLKANDE clearly demonstrated the feasibility of the astrophysical observation of Solar neutrinos; i.e., with the signal time, the signal direction and the signal energy spectrum. • Super KAMIOKANDE is making a continuous observation of Solar neutrinos with much better resolution and statistics. • The signal timing is better than a few nanosecond. • The directional observation is shown in the next slide. The directional resolution is not as good as one hopes for. The next slide shows the picture of the sun as seen by neutrinos. • The following slide shows the observed n-energy spectrum as compared with the theoretically expected. • The next slide shows the theoretical neutrino energy spectrum and the summary of the rate measurements.

4. Directional Observation of Solar Neutrinos 2008 Super-KAMIOKANDE 1988 KAMIOKANDE of Ref. 1)

5. The first n-graph , not photo-graph, of the sun. The orbit of the sun in the Galaxy

6. Energy Spectrum of Solar neutrinos 2008 SuperKAMIOKANDE 1988 KAMIOKANDE of Ref.１）

7. Summary of the Solar neutrino data Rate measurements @ Neutrino 2002 Target Data / SSM (BP2000.2) ・ Homestake 37Cl 0.34±0.03 ・ SAGE 71Ga 0.55±0.05 ・ GALLEX+GNO 71Ga 0.55±0.05 ・ Super-K e- (water) 0.465±0.016 ・ SNO (CC) d (D2O) 0.348±0.020 ・ SNO (NC) d (D2O) 1.01±0.13 B.T.Cleveland et al., Astrophys. J 496 (1998) 505 J.N.Abdurashitov et al., Nucl. Phys. Proc. Suppl. (Neutrino 2002) 118 (2003) 39 T.A.Kirsten for the GNO collab. Nucl. Phys. Proc. Suppl. (Neutrino 2002) 118 (2003) 33. S.Fukuda et al., Phys. Lett. B 539 (2002) 179. Q.R. Ahmad et al., Phys. Rev. Lett. 89 (2002) 011301 http://www.sns.ias.edu/~jnb/

8. 2) future supernova n`s, • The new Type-II supernova did not happen in our Milky Way Galaxy and I can show you just a hopeful expectation. See the next slide.

9. Supernova Neutrinos Expected for Super-KAMIOKANDE at 10kpc, (n-oscillation effects not included) (1987)

10. 3) dark matter search with the sun as their reservoir, • The negative result of some attempt is shown in the next slide.

11. Dark matter search with the Sun as their reservoir 90% CL limit on WIMP parameter space for a WIMP with spin dependent coupling 90% CL flux limit on the WIMP-induced upward going muons S. Desai et al. (Super-K collab), Phys. Rev. D 70, 083523 (2004),

12. 4) n-oscillation, • The neutrino oscillation discovered by KAMIOKANDE is firmly established by Super KAMIKANDE. • See the next 3 slides. • The first shows the flight path dependence of atmospheric nm and ne. • The second is showing the determination of nm→nt oscillation parameters; Dm22 3 and q2 3 . The data of long base line oscillation experiments, K2K and MINOS, were also included. • The third is the determination of Dm212 and q1 2using the data of solar neutrino, ne, and those of anti- ne obtained by KamLAND experiment.

13. Neutrino Oscillation 2008 Super-KAMIOKANDE 1988 KAMIOKANDE Sub-GeV e-like Sub-GeV m-like Kamiokande collab:. Phys. Lett. B 205, 416 (1988)

14. Oscillation parameters (1): Atmospheric + long baseline experiments 1988 2008 nmnt 90% CL 68% CL K2K MINOS SK (Zenith) SK (L/E) M.H.Ahn et al. (K2K collab.), Phys. Rev. D 74, 072003 (2006). MINOS collab. arXiv:0708.1495 [hep-ex] Ref.1)

15. Oscillation parameters (2): Solar + KamLAND experiments S. Abe et al. (KamLAND collab.), arXiv:0801.4589 [hep-ex]

16. 5) high energy n point sources • There are a number of experimental project aiming at this aim. In the next slide an overall view is shown.

17. High energy neutrino astronomy (2008) South pole Mediterranean Sea Antares NEMO IceCube KM3NeT NESTOR

18. 20 more years to come • There will be another long baseline n-oscillation experiment using a very intense neutrino beam from Tokai J-PARK proton accelerator. This experiment T2K will start data-taking next year, hopefully to pin down the small and still undetermined q1,3 . • The remaining oscillation parameter is CP violation parameter. We still do not know how to approach this problem. • Intense efforts should be given to double beta decay experiments, since this seems to be the only channel we can look into the Majorana nature of neutrino. • The last and the most difficult problem still remaining to be solved is the observation of Cosmic n Background which would tell us the state of our Universe a few second after the Big-Bang. At present we do not know the best way to approach this problem. A serious theoretical analysis of the neutrino reflection, and refraction, is being carried out by J. Arafune and G. Takeda, the result of which I hope we can see in near future. • Last year we worked on the latest resume of neutrino physics and it will be published this summer 2) . • For the sake of helping the younger participants of this Workshop the full list of publications by the three experiments at Kamioka is attached at the end.

19. Aknowledgement • The help rendered by Profs. T. Kajita and M. Nakahata of ICRR, University of Tokyo, in preparing this talk is greatly appreciated. Thank youfor your patience. M. Koshiba

20. Reference1) Imaging Water Cerenkov Detector; Why and How?: M. Koshiba; Proc. International Workshop on Neutrino Telescopes, 1988.2) M. Koshiba et al; Landolt-Bernstein New Series. O.1/21A,Elementary ParticlesTheory and Experiment.; Springer (2008) ISBN 978-3-540-74202-9.

21. KAMIOKANDEpublications K-1) Search for Nucleon Decay into Charged Lepton + Mesons; K.Arisaka et al.,J. Phys. Soc. Japan 54, 3213 (1985) K-2) Search for Nucleon Decays Catalyzed by Magnetic Monopoles; T. Kajita et al., J. Phys. Soc. Japan 54, 4065 (1985) K-3) Search for Nucleon Decays into Anti-Neutrino + Mesons; T. Kajita et al.,J. Phys. Soc. Japan 55, 711 (1986) K-4) Search for High Energy Muons from Cygnus X-3; Y. Oyama et al.,Phys. Rev. Lett. 56, 991 (1986) K-5) Search for Neutron-Antineutron Oscillation in 16O Nuclei ; M.Takita et al.,Phys. Rev. D 34, 902 (1986) K-6) Atmospheric Neutrino Background and Pion Nuclear Effect for KAMIOKA Nucleon Decay Experiment; M.Nakahata et al.,J. Phys. Soc. Japan 55, 3786 (1986) K-7) Observation of a Neutrino Burst from the Supernova SN1987a; K. Hirata et al.,Phys. Rev. Lett. 58, 1490 (1987) K-8) Search for high-energy muons from Cygnus X-3 during the radio outbursts in 1983 and 1985; Y Oyama et al. Phys. Rev. D 36, 3537 (1987) K-9) Search for High-Energy Neutrinos from SN1987A : First Six Months; Y. Oyama et al., Phys. Rev. Lett. 59, 2604 (1987) K-10) Experimental Study of the Atmospheric Neutrino Flux; K.S.Hirata et al., Phys. Lett. B 205, 416 (1988) K-11) Observation in the KAMIOKANDE-II Detector of the Neutrino Burst from Supernova SN1987A; K.S.Hirata et al., Phys. Rev. D 38, 448 (1988) K-12) Experimental Limit on the Flux of Relic Antineutrinos from Past Supernovae; W. Zhang et al.,Phys. Rev. Lett. 61, 385 (1988) K-13) Search for Correlation of Neutrino Events with Solar Flares in Kamiokande; K.S.Hirata et al., Phys. Rev. Lett. 61, 2653 (1988) K-14) Experimental Study of Upward-going Muons in Kamiokande; Y. Oyama et al.,Phys. Rev. D 39, 1481 (1989) K-15) Experimental Limits on Nucleon Lifetime for Lepton + Meson Decay Modes; K.S.Hirata et al., Phys. Lett. B 220, 308 (1989) K-16) Observation of 8B Solar Neutrinos in the Kamiokande-II Detector; K.S.Hirata et al., Phys. Rev. Lett. 63, 16 (1989) K-17) Search for Neutrino Events in the Kamiokande II Detector in Correlation with the Solar Flare Activity in 1989 March.; K.S.Hirata et al., Ap. J. 359, 574 (1990 K-18) Results from One Thousand Days of Real-Time, Directional Solar-Neutrino Data.; K.S.Hirata et al., Phys. Rev. Lett. 65, 1297 (1990) K-19) Constraints on Neutrino Oscillation Parameters from the Kamiokande Solar Neutrino Data.; K.S.Hirata, et al., Phys. Rev. Lett. 65, 1301 (1991) K-20) Search for Day-Night and Semiannual Variations in the Solar Neutrino Flux Observed in the Kamiokande-II Detector.; K.S.Hirata et al., Phys. Rev. Lett. 66, 9 (1991) K-21) Search for Fractionally Charged Particles in Kamiokande-II.; M. Mori et al.,Phys. Rev. D 43, 2843 (1991) K-22) Measurements of Charge Ratio and Polarization of 1.2 TeV/c Cosmic-Ray Muons with the Kamiokande-II Detector.；M. Yamada et al., Phys. Rev. D 44, 617 (1991) K-23) Mass Limits for Dark-Matter Particles Derived from High-Energy Neutrinos from the Sun.；N.Sato et al., Phys. Rev. D 44, 2220 (1991) K-24) Time Variation of the Cosmic Ray Muon Flux in Underground Detectors and Correlation with Atmospheric Temperature.; K. Munakata et al., J. Phys. Soc. Japan, 60, 2808 (1991) K-25) Search for Neutralino Dark Matter in Kamiokande.; M.Mori et al., Phys. Lett. B 270, 89 (1991)

22. K-26) Real-time, Directional Measurement of 8B Solar Neutrinos in the Kamiokande-II Detector. K. S.Hirata et al. ,Phys. Rev. D 44, 2241 (1991) K-27) A Limit on Spontaneous R-parity Breaking from Kamiokande.; M.Mori et al., Phys. Lett. B 278, 217 (1992) K-28) Observation of a Small Atmospheric nm/ne Ratio in Kamiokande.; K.S. Hirata et al., Phys. Lett. B 280, 146 (1992) K-29) Search for Neutrino-induced low-energy-electron-event Clusters in Kamiokande-II.; K.S. Hirata, et al., Phys. Rev. D 45, 3355 (1992) K-30) Survey of Atmospheric Neutrino Data and Implications for Neutrino Mass and Mixing.; E.W.Beier, et al., Phys. Lett. B 283, 446 (1992) K-31) A Limit on Massive Neutrino Dark Matter from Kamiokande; M.Mori et al.,Phys. Lett. B 289, 463 (1992) K-32) Study of Invisible Nucleon Decay, n n n n, and a Forbidden Nuclear Transition in the Kamiokande Detector; Y. Suzuki et al., Phys. Lett. B 311, 357 (1993) K-33) Search for Neutralino Dark Matter Heavier than the W boson at Kamiokande; M. Mori et al., Phys. Rev. D 48, 5505 (1994) K-34) Atmospheric nm/ne Ratio in the Multi-GeV Energy Range; Y. Fukuda et al., Phys. Lett. B 335, 237 (1994) K-35) Search for Low-Energy Neutrinos from Galactic Gamma-ray Sources: Y. Fukuda et al.,Ap. J. 435, 225 (1994) K-36) Study of Neutron Background in the Atmospheric Neutrino Sample. ; Y. Fukuda et al., Phys. Lett. B 388, 397 (1996) K-37) Solar Neutrino Data Covering Solar Cycle 22.; Y. Fukuda et al., Phys. Rev. Lett. 77, 1683 (1996) K-38) Large-Scale Anisotropy of the Cosmic-ray muon flux in Kamiokande.; K. Munakata et al., Phys. Rev. D 56, 23 (1996) K-39) Measurement of the Flux and Zenith-Angle Distribution of Upward Through-Going Muons in Kamiokande II+III. ; S.Hatakeyama et al., Phys. Rev.Lett. 81, 2016 (1998) Super-Kamiokande publications SK-1) Measurement of a Small Atmospheric nm/ne Ratio ; Y.Fukuda et al., Phys. Lett. B 433, 9 (1998) SK-2) Measurements of the Solar Neutrino Flux from Super-Kamioknade's First 300 Days. ; Y. Fukuda et al., Phys. Rev. Lett. 81, 1158 (1998) SK-3) Study of the Atmospheric Neutrino Flux in the Multi-GeV Energy Range ; Y. Fukuda et al., Phys. Lett. B 436, 33 (1998) SK-4) Evidence for Oscillation of Atmospheric Neutrinos.; Y. Fukuda et al., Phys. Rev. Lett. 81, 1562 (1998) SK-5) Search for Proton Decay via p  e+ + p0 in a Large Water Cherenkov Detector ; M. Shiozawa et al., Phys. Rev.Lett. 81, 3319 (1998) SK-6) Calibration of Super-Kamiokande Using an Electron LINAC ; M. Nakahata et al., Nucl. Instrum. Meth. A 421, 113 (1999) SK-7) Development of High Sensitive Radon Detectors ; Y. Takeuchi et al., Nucl. Instrum. Meth. A 421, 334 (1999) SK-8) Search for Proton Decay through p  n K+ in a Large Water Cherenkov Detector; Y. Hayato et al., Phys. Rev. Lett. 82, 1529 (1999) SK-9) Constraints on Neutrino Oscillation Parameters from the Measurement of Day-Night Solar Neutrino Fluxes at Super- Y. Fukuda et al., Phys. Rev. Lett. 82, 1810 (1999) SK-10) Measurement of Solar Neutrino Energy Spectrum Using Neutrino-Electron Scattering ; Y. Fukuda et al., Phys. Rev. Lett. 82, 2430 (1999)

23. SK-11) Measurement of Radon Concentrations at Super-Kamiokande ; Y.Takeuchi et al., Phys. Lett. B 452, 418 (1999) SK-12) Measurement of the Flux and Zenith-Angle Distribution of Upward Throughgoing Muons ｂy Super-Kamiokande; Y. Fukuda et al., Phys. Rev. Lett. 82, 2644 (1999) SK-13) Observation of the East-West Anisotropy of the Atmospheric Neutrino Flux: Y.Futagami et al., Phys. Rev. Lett. 82, 5194 (1999) SK-14) Neutrino induced upward stopping muons in Super-Kamiokande ; Y.Fukuda et al., Phys. Lett. B 467, 185 (1999) SK-15) Tau neutrinos favored over sterile neutrinos in atmospheric muon neutrino oscillations ; S.Fukuda et al., Phys. Rev. Lett. 85, 3999 (2000) SK-16) 16N as a Calibration Source for Super-Kamiokande.; E. Blaufuss et al., Nucl. Inst. Meth. A 458, 638 (2001) SK-17) Solar 8B and Hep Neutrino Measurements from 1258 Days of Super-Kamiokande Data.; S. Fukuda et al., Phys. Rev. Lett. 86, 5651 (2001) SK-18) Constraints on Neutrino Oscillations using 1258 Days of Super-Kamiokande Solar Neutrino Data.; S. Fukuda et al., Phys. Rev. Lett. 86, 5656 (2001) SK-19) Search for Neutrinos from Gamma-ray Bursts using Super-Kamiokande ; S. Fukuda et al., Astrophys. J. 578, 317 (2002) SK-20) Determination of Solar Neutrino Oscillation Parameters using 1496 days of Super-Kamiokande Data; S.Fukuda et al., Phys. Lett. B 539, 179 (2002) SK-21) Search for Supernova Relic Neutrinos at Super-Kamiokande; M.Malek et al., Phys. Rev. Lett. 90, 061101 (2003) SK-22) Search for anti-ne from the Sun at Super-Kamiokande I ; Y.Gando et al., Phys. Rev. Lett. 90, 171302 (2003) SK-23) The Super-Kamiokande Detector; Y.Fukuda et al., Nucl. Instrum. Meth. A 501, 418 (2003) SK-24) A Search for periodic modulations of the solar neutrino flux in Super-Kamiokande I； J. Yoo et al., Phys. Rev. D 68, 092002 (2003). SK-25) Precise measurement of the solar neutrino day / night and seasonal variation in Super-Kamiokande-1； M.B.Smy et al., Phys. Rev. D 69, 011104 (2004). SK-26) Evidence for an oscillatory signature in atmospheric neutrino oscillation；Y. Ashie et al., Phys. Rev. Lett. 93, 101801 (2004). SK-27) Search for dark matter WIMPs using upward through-going muons in Super-Kamiokande； S. Desai et al.,Phys. Rev. D 70, 083523 (2004), Erratum-ibid.D 70, 109901 (2004). SK-28) Search for nucleon decay via modes favored by supersymmetric grand unification models in Super-Kamiokande-I； K. Kobayashi et al., Phys. Rev. D 72, 052007 (2005). SK-29) A Measurement of atmospheric neutrino oscillation parameters by SUPER-KAMIOKANDE I； Y.Ashie et al., Phys. Rev. D 71, 112005 (2005). SK-30) Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data； D. W. Liu et al., Phys. Rev. Lett. 93, 021802 (2004). SK-31) Solar neutrino measurements in super-Kamiokande-I； J. Hosaka et al.,Phys. Rev. D 73, 112001 (2006). SK-32) A Measurement of atmospheric neutrino flux consistent with tau neutrino appearance; K .Abe et al., Phys. Rev. Lett. 97, 171801 (2006) SK-33) High energy neutrino astronomy using upward-going muons in Super-Kamiokande-I； K. Abeet al. Astrophys. J. 652, 198 (2006).

24. SK-34) Search for Diffuse Astrophysical Neutrino Flux Using Ultrahigh Energy Upward-Going Muons in Super-Kamiokande I.； Molly E.C.Swanson et al. Astrophys. J. 652, 206-215 (2006). SK-35) Three flavor neutrino oscillation analysis of atmospheric neutrinos in Super-Kamiokande； J. Hosaka et al. Phys. Rev. D 74, 032002 (2006). SK-36) Observation of the anisotropy of 10-TeV primary cosmic ray nuclei flux with the super-kamiokande-I detector； G. Guillian et al., Phys.Rev.D75:062003,2007 SK-37) Search for neutral Q-balls in super-Kamiokande II； Y. Takenaga et al., Phys. Lett. B 647, 18-22 (2007). SK-38) Search for Supernova Neutrino Bursts at Super-Kamiokande.； M.Ikeda et al. Astrophys. J. 669, 519-524 (2007). SK-39)Search for matter-dependent atmospheric neutrino oscillations in Super-Kamiokande.： K.Abe et al.. Phys. Rev. D77, 052001 (2008) KamLANDpublications KL-1) First Results from KamLAND: Evidence for Reactor Anti-neutrino Disappearance. K. Eguchi et al.Phys.Rev.Lett.90:021802,2003 KL-2) A High Sensitivity Search for Anti-nu(e)‘s from the Sun and Other Sources at KamLAND;.; K. Eguchi et al..     Phys.Rev.Lett.92:071301,2004KL-3) Experimental Investigation of Geologically Produced Antineutrinos with KamLAND.; T. Araki et al.. Nature 436:499-503,2005KL-4) Measurement of Neutrino Oscillation with KamLAND: Evidence of Spectral Distortion;. T.Araki et al..     Phys.Rev.Lett.94:081801,2005KL-5) Search for the invisible decay of neutrons with KamLAND: .KT. Araki et al..Phys.Rev.Lett.96:101802,2006.