New Results from KamLAND and Prospects for Observation of Terrestrial Neutrinos

1. New Results from KamLAND and Prospects for Observation ofTerrestrial Neutrinos Nikolai Tolich

2. KamLAND Collaboration T. Araki1, K. Eguchi1, S. Enomoto1, K. Furuno1, K. Ichimura1, H. Ikeda1, K. Inoue1, K. Ishihara1, T. Iwamoto1, T. Kawashima1, Y. Kishimoto1, M. Koga1, Y. Koseki1, T. Maeda1, T. Mitsui1, M. Motoki1, K. Nakajima1, H. Ogawa1, K. Owada1, J.-S. Ricol1, I. Shimizu1, J. Shirai1, F. Suekane1, A. Suzuki1, K. Tada1, O. Tajima1, K. Tamae1, Y. Tsuda1, H. Watanabe1, J. Busenitz2, T. Classen2, Z. Djurcic2, G. Keefer2, K. McKinny2, D-M. Mei2, A. Piepke2, E. Yakushev2, B.E. Berger3, Y.D. Chan3, M.P. Decowski3, D.A. Dwyer3, S.J. Freedman3, Y. Fu3, B.K. Fujikawa3, J. Goldman3, F. Gray3, K.M. Heeger3, K.T. Lesko3, K.-B. Luk3, H. Murayama3, A.W.P. Poon3, H.M. Steiner3, L.A. Winslow3, G.A. Horton-Smith4, C. Mauger4, R.D. McKeown4, P. Vogel4, C.E. Lane5, T. Miletic5, P.W. Gorham6, G. Guillian6, J.G. Learned6, J. Maricic6, S. Matsuno6, S. Pakvasa6, S. Dazeley7, S. Hatakeyama7, A.Rojas7, R. Svoboda7, B.D. Dieterle8, J. Detwiler9, G. Gratta9, K. Ishii9, N. Tolich9, Y. Uchida9, M. Batygov10, W. Bugg10, Y. Efremenko10, Y. Kamyshkov10, A. Kozlov10, Y. Nakamura10, H.J. Karwowski11, D.M. Markoff11, J.A. Messimore11, K. Nakamura11, R.M. Rohm11, W. Tornow11, R. Wendell11, A.R. Young11, M.-J. Chen12, Y.-F. Wang12, and F. Piquemal13 1Research Center for Neutrino Science, Tohoku University, Sendai 980-8578, Japan 2Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487, USA 3Physics Department, University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 4W. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA 5Physics Department, Drexel University, Philadelphia, Pennsylvania 19104, USA 6Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA 7Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA 8Physics Department, University of New Mexico, Albuquerque, New Mexico 87131, USA 9Physics Department, Stanford University, Stanford, California 94305, USA 10Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA 11Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA and Physics Departments at Duke University, North Carolina State University, and the University of North Carolina at Chapel Hill 12Institute of High Energy Physics, Beijing 100039, People's Republic of China 13CEN Bordeaux-Gradignan, IN2P3-CNRS and University Boreaux I, F-33175 Gradignan Cedex, France LBL Journal Club Meeting

3. An Attractive Group LBL Journal Club Meeting

4. ne Detecting Anti-neutrinos at KamLAND Delayed Prompt • KamLAND (Kamioka Liquid scintillator Anti-Neutrino Detector) 2.2 MeVg 0.5 MeV e- 0.5 MeV n e+ p p d • Inverse beta decay ne + p → e+ + n • The positron losses its energy then annihilates with an electron • The neutron first thermalizes then captures on a proton with a mean capture time of ~200ms LBL Journal Club Meeting

5. 1km Overburden Detector Electronics Hut Steel Sphere PMTs 1325 17” 554 20” 34% coverage 1 kton liquid-scintillator Water Cherenkov outer detector 225 PMTs LBL Journal Club Meeting

6. Inside the Detector LBL Journal Club Meeting

7. KamLAND Situated to Detect Reactor Anti-neutrinos Kashiwazaki KamLAND Takahama Ohi LBL Journal Club Meeting

8. History Repeating Fred Reines preparing a neutrino detector (circa 1953) LBL Journal Club Meeting

9. So were Fred Reines background from Terrestrial Anti-neutrinos? LBL Journal Club Meeting

10. Total Heat from the Earth • Conductive heat flow measured from bore-hole temperature gradient and conductivity • Total heat flow 44TW • In 1862 Lord Kelvin used the temperature gradient to estimate the age of the Earth to be 20-400 million years old LBL Journal Club Meeting

11. Radiogenic Heat • 238U generates 8.0TW of radiongenic heat in the Earth • 232Th generates 8.3TW of radiongenic heat in the Earth • Beta decays produce electron anti-neutrinos LBL Journal Club Meeting

12. Terrestrial Anti-neutrino signal 238U decay chain 232Th decay chain • KamLAND is only sensitive to anti-neutrinos above 1800keV LBL Journal Club Meeting

13. Terrestrial Anti-neutrino signal at KamLAND U U+Th Reactor Background LBL Journal Club Meeting

14. Structure of the Earth • Structure of the Earth determined from Seismic data Image by Colin Rose LBL Journal Club Meeting

15. Convection in the Earth • The mantle convects even though it is solid • Oceanic crust is being renewed at mid-ocean ridges and recycled at subduction zones LBL Journal Club Meeting

16. U and Th in the Earth • U and Th are thought to be absent from the core and present in the Silicate Earth at ~2.75 times CI carbonaceous chondrites concentrations • The U concentration in the silicate Earth is 20ppm • The Th concentration in the silicate Earth is 80ppm • The Th/U ratio is ~4 LBL Journal Club Meeting

17. The Expected TerrestrialAnti-neutrino Flux • Given a model of the Earth the anti-neutrino flux per unit energy at KamLAND can be calculated • The activity per unit mass • The number of neutrinos per decay chain per unit energy • The mass concentration as a function of position in the Earth • The density as a function of position in the Earth • The neutrino survival probability as a function of distance from KamLAND LBL Journal Club Meeting

18. Earth split into eight sections: Upper Continental Crust (UCC), Middle Continental Crust (MCC), Lower Continental Crust (LCC), Oceanic Crust (OC), Upper Mantle (UM), Lower Mantle (LM), Continental Sediment (CS), Oceanic Sediment (OS) Reference Earth Model LBL Journal Club Meeting

19. Cumulative Terrestrial Anti-neutrino Flux Expected at KamLAND LBL Journal Club Meeting

20. Terrestrial Anti-neutrino map of the Earth LBL Journal Club Meeting

21. Measurement at KamLAND Measured Total Heat Flow Total LBL Journal Club Meeting

22. New Reactor Results* *T. Araki et al. arXiv:hep-ex/0406035 June 13, 2004 submitted to Phys. Rev. Lett.

23. Introduction to reactor measurement KamLAND ne Nuclear Reactor L LBL Journal Club Meeting

24. Determining the Event Vertex (2.5MeV) (1.1MeV) (1.0MeV) LBL Journal Club Meeting

25. τ=29.1ms Q=13.4MeV 12B 12N τ=15.9ms Q=17.3MeV μ Tagged Cosmogenics used as Calibration Device LBL Journal Club Meeting

26. Energy Calibration Using g Sources and 12B/12N n-p n-12C 68Ge 60Co 65Zn LBL Journal Club Meeting

27. Selecting Electron Anti-neutrinos • Rprompt, Rdelayed < 5.5m • ΔR < 2m • 0.5μs < ΔT < 1ms • 1.8MeV < Edelayed < 2.6MeV • 2.6MeV < Eprompt < 8.5MeV • 89.8% tagging efficiency • 33% increase in volume Delayed Prompt 2.2 MeVg 0.5 MeV 0.5 MeV e+ LBL Journal Club Meeting

28. Japan Nuclear Reactor Scandal LBL Journal Club Meeting

29. 2003 saw a substantial dip in reactor anti-neutrino flux LBL Journal Club Meeting

30. Good correlation with reactor flux Fit constrained through known background c2/dof=2.1/4 No oscillation expected 90% CL LBL Journal Club Meeting

31. Energy spectrum shows distortion • Best fit c2/dof=18.3/18 (goodness of fit is 42%) • Fit to rescaled reactor spectrum c2/dof=43.4/19 (excluded at 99.89% CL) LBL Journal Club Meeting

32. Oscillations with L/E KamLAND sees reactor neutrinos from different distances Hypothetical oscillation curve for single reactor distance LBL Journal Club Meeting

33. Alternative neutrino propagation models • Decay* excluded at 95% CL • Decoherence† excluded at 94% CL *V.Barger et al. Phys. Rev. Lett., 82(1999) 2640 †E.Lisi et al. Phys. Rev. Lett., 85 (2000) 1166 LBL Journal Club Meeting

34. Two flavor rate and shape analysis New Result Previous Result • LMA2 excluded at 99.6% CL • Best fit • Dm2=8.3×10-5eV2 • sin22q=0.83 • LMA0 excluded at 94% CL LBL Journal Club Meeting

35. Combined solar and KamLAND two flavor result LBL Journal Club Meeting