Recent Results and Prospects from KamLAND

1
Recent Results and Prospects from KamLAND

• 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

3
Introduction to reactor measurement
KamLAND
ne
Nuclear Reactor
L
4
KamLAND Situated to Detect Reactor Anti-neutrinos
Kashiwazaki
KamLAND
Takahama
Ohi
5
Detecting Anti-neutrinos at KamLAND
Delayed
Prompt

• KamLAND (Kamioka Liquid scintillator
  Anti-Neutrino Detector)

2.2 MeV g
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

6
The Detector
1km Overburden
Electronics Hut
Steel Sphere
PMTs 1325 17 554 20 34 coverage
1 kton liquid-scintillator
Water Cherenkov outer detector 225 PMTs
7
Inside the Detector
8
Determining the Event Vertex
(2.5MeV) (1.1MeV) (1.0MeV)
9
Tagged Cosmogenics used as Calibration Device
10
Fraction of volume used verifiedusing µ-produced
12B/12N and n
Neutrons
12B/12N
11
Energy Calibration Using g Sources and 12B/12N
n-p
n-12C
68Ge
60Co
65Zn

• Includes Birks law, Cherenkov light to obtain
  constants for ? and etype depositions

12
Selecting Electron Anti-neutrinos

• Rprompt, Rdelayed lt 5.5m
• ?R lt 2m
• 0.5µs lt ?T lt 1ms
• 1.8MeV lt Edelayed lt 2.6MeV
• 2.6MeV lt Eprompt lt 8.5MeV

• 89.8 tagging efficiency
• 33 increase in volume

Delayed
Prompt
2.2 MeV g
0.5 MeV ?
0.5 MeV ?
e
13
Japan Nuclear Reactor Scandal
14
2003 saw a substantial dip in reactor
anti-neutrino flux
15
Good correlation with reactor flux
Fit constrained through known background
c2/dof2.1/4
No oscillation expected
90 CL
16
Energy spectrum shows distortion

• Best fit c2/dof18.3/18 (goodness of fit is 42)

• Fit to rescaled reactor spectrum c2/dof43.4/19
  (excluded at 99.89 CL)

17
Oscillations with L/E
KamLAND sees reactor neutrinos from different
distances
Hypothetical oscillation curve for single reactor
distance
18
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
19
Two flavor rate and shape analysis

• LMA2 excluded at 99.6 CL

• Best fit
• Dm28.310-5eV2
• sin22q0.83

• LMA0 excluded at 94 CL

20
Improvement since first result
Previous Result
New Result
21
Combined solar and KamLAND two flavor result
22
Prospects

• Measure the global concentration of U and Th in
  the Earth
• Solar anti-neutrinos
• Solar neutrinos
• Exotic nucleon decay modes
• Observe supernova neutrinos

Geo Signal
Reactor Signal