motoki@NDM03

M.Motoki 　（ Tohoku University)For the KamLAND Collaboration

First results from KamLAND

motoki@NDM03

SNO NC; e++

Flavor transitionday/night

LMA

NeutrinoNeutrino OscillationOscillation

KamLAND; Artificial neutrino sourcesLow energy Long baseline

LMA

SMA

LOW

VAC

SuperK day night, SuperK 　　　　 energy spectrum LMA+LOW

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KamLANDKamLANDKamKamiokaioka LLiquid scintillator iquid scintillator AAnti nti NNeutrino eutrino DDetectoretector

Reactor Anti Neutrino Source.Reactor Anti Neutrino Source. Energy distortion, LMAEnergy distortion, LMA 77Be neutrinos.Be neutrinos. Geo neutrinos.Geo neutrinos.

motoki@NDM03

The KamLAND CollaborationK.Eguchi, S.Enomoto, K.Furuno, J.Goldman, H.Hanada, H.Ikeda, K.Ikeda, K.Inoue, K.Ishihara, W.Itoh, T.Iwamoto, T.Kwaguchi, T.Kawashima, H.Kinoshita, Y.Kishimoto, M.Koga, Y.Koseki, T.Maeda, T.Mitsui, M.Motoki, K.Nakajima, M.Nakajima, T.Nakajima, H.Ogawa, K.Owada,

T.Sakabe, I.Shimizu, J.Shirai, F.Suekane, A.Suzuki, K.Tada, O.Tajima, T.Takayama, K.Tamae, H.Watanabe

Tohoku UniversityJ.Busenitz, Z.Djurcic, K.McKinny, D.-M.Mei, A.Piepke, E.Yakushev,

University of AlabamaB.E.Berger, Y.D.Chan, M.P.Decowski, D.A.Dwyer, S.J.Freedman, Y.Fu, B.K.Fujikawa, K.M.Heeger, K.T.Lesko, K.-B.Luk, H.Murayama, D.R.

Nygren, C.E.Okada, A.W.P.Poon, H.M.Steiner, L.A.Winslow

LBNL/UC BerkeleyG.A.Horton-Smith, R.D.McKeown, J.Ritter, B.Tipton, P.Vogel

California Institute of TechnologyC.E.Lane, T.Miletic

Drexel UniversityP.W.Gorham, G.Guillian, J.G.Learned, J.Maricic, S.Matsuno, S.Pakvasa

University of HawaiiS.Dazeley, S.Hatakeyama, M.Murakami, R.C.Svoboda

Louisiana State UniversityB.D.Dieterle, M.DiMauro

University of New MexicoJ.Detwieler, G.Gratta, K.Ishii, N.Tolich, Y.Uchida

Stanford UniversityM.Batygov, W.Bugg, H.Cohn, Y.Efremenko, Y.Kamyshkov, A.Kozlov, Y.Nakamura

University of TennesseeL.De Braeckeleer, C.R.Gould, H.J.Karwowski, D.M.Markoff, J.A.Messimore, K.Nakamura, R.M.Rohm, W.Tornow, A.R.Young

TUNLY.-F.Wang

IHEP,Beijing

motoki@NDM03

a few /day in KamLAND

• 54 Japanese Reactors

• Average distance 180km

• (79 % in 138-214km)

• < Eν> ～ 4MeV

• ⊿m2 ～ E/L ～ 10-5 eV2

• Suitable to test LMA solution

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Reactor neutrino flux at KamLANDReactor neutrino flux at KamLAND

• Thermal power, Burn-up, : available for All 54 Japanese Reactors• Reactor type, Volume ratio of new fuel, Enrichment of new fuel, initial mean burn up• Simple model of reactor core.

– fission rate– energy spectrum @KamLANDUncertainty : 2.5% for anti νe

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Reactor Neutrino detection in Liquid Scintillator

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Vertex reconstructionVertex reconstruction

Typically 25cm resolutionPosition reconstruction: 5cm

Using PMT timing information

Source Calibration Data: Z-axis

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Vertex Fitter Performance: Fiducial Volume

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Energy Energy resolutionresolution

Along to Z-axis: radioactive source68Ge ( + ) : 1.012 MeV 65Zn () : 1.116 MeV 60Co ( + ) : 2.506 MeV AmBe (,n) : 2.20, 4.40, 7.6 MeV time dependence: 0.6%

4πcalibration: captured netron events n+pd+MeVn+12C13C+: 4.9MeV position dependence: 1.1%E/E ~ 7.5% /√E [MeV]Esyst=1.9% at 2.6MeV

2.1% for anti e

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Radio active Background Radio active Background in LSin LS

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T = |tprompt – t delayed|

214Po:s

214214Bi – Bi – 214214Po – Po – 210210Pb SignalPb Signaldelayedprompt

238U = (3.5±0.5)x10-18 g/g

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Delayed coincidence

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Vertex position after Vertex position after delayed coincidencedelayed coincidence

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Prompt

Delayed

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KamLAND KamLAND resultresult

)(041.0

)(085.0611.0N

NN

expected

bgobs

sys

stat

Mar. 4 – Oct. 6, 2002162 ton•yr (145.1 days)

Observed 54 events (E>2.6MeV)

Background 1 ± 1 events

Expected 86.8 ± 5.6 events

Geo Neutrino: 0 – 110 TW (95 % C.L.)

motoki@NDM03

Spectral Distortion?Spectral Distortion?

2- oscillation: best-fit No oscillation, flux suppression

Data and best oscillation fit

consistent at 93% C.L. Data and scaled no-oscillation shape consistent at 53% C.L

Need more reactor neutrino and calibration data

motoki@NDM03

KamLAND impactsKamLAND impacts

95%CL

Best fit LMA KamLAND

sin22 0.833 1.0m2[eV2] 5.5 x 10-5 6.9 x 10-5

KamLAND All combined

LMA 2

LMA 1

motoki@NDM03

KamLAND ProspectsKamLAND Prospects

• Neutrino Oscillation? Precision measurements– Energy Spectrum distortion?

– Current reactor power in Japan ~50%.

– A new reactor is coming.

– LMA 1 or LMA2

• 7Be – Purification system improvement

motoki@NDM03

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LMA I, LMA IIBefore and AfterNew Reactor “Shika”

motoki@NDM03

KamLANKamLAND D

SolarSolar )%99%(4.4 CL

motoki@NDM03

SummarySummary Last year

– KamLAND saw a clear deficit in reactor neutrinos.

• Future– KamLAND purification system will be improved for

7Be Solar Neutrino detection.– Stable data taking during reactor shutdown.– LMA1,LMA2 will be decided.

motoki@NDM03

Appendix

motoki@NDM03

Solar Neutrino at Solar Neutrino at KamLANDKamLAND

First observation of real time 7Be neutrinos

Background Current Goal Method238U 3.5 ×10-18g/g OK

232Th 5.2 ×10-17g/g OK222Rn 3.3×10-8Bq/m-3 OK

40K <2.7 ×10-16g/g <10-18g/g Water Extraction210Pb ~10-20g/g 5 ×10-25g/g Water Extraction85Kr 0.7Bq/m-3 10-6Bq/m-3 N2 purge

222Rn leak N2 purge/ air tight valves