Prompt event energy spectrum of electron anti-neutrino candidate events. All histograms corresponding to reactor spectra and expected backgrounds incorporate the energy-dependent selection efficiency (top panel). The shaded background and geo-neutrino histograms are cumulative. The data show the statistical uncertainties, the band on the blue histogram indicates the event rate systematic uncertainty.

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Allowed region for neutrino oscillation parameters from KamLAND and solar neutrino experiments. The side-panels show the Δ χ²-profiles for KamLAND (dashed) and solar experiments (dotted) individually, as well as the combination of the two (solid).

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The low-energy region of the electron anti-neutrino spectrum relevant for geo-neutrinos. The main panel shows the data with the fitted background and geo-neutrino contributions; the upper panel compares the background and reactor-anti-neutrino-subtracted data to the number of geo-neutrinos for the decay chains of U (dashed) and Th (dotted) calculated from a geological reference model.

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Ratio of the background and geo-neutrino subtracted electron anti-neutrino spectrum to the expectation for no-oscillation as a function of L/E. L is the effective baseline taken as a flux-weighted average (L=180km); the energy bins are equal probability bins of the best-fit including all backgrounds. The histogram and curve show the expectation accounting for the distances to the individual reactors, time-dependent flux variations and efficiencies. The error bars are statistical and do not include correlated systematic uncertainties in the energy scale.

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Survival probability described in the previous figure with L/E range extended to 0 km/MeV. The point derived from the Chooz data ( short baseline ) is included.

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Main panel, experimental points together with the total expectation (thin dotted black line). Also shown are the total expected spectrum excluding the geoneutrino signal (thick solid black line), the expected signals from ²³⁸U (dot-dashed red line) and ²³²Th (dotted green line) geoneutrinos, and the backgrounds due to reactor nu macre (dashed light blue line), ¹³C(alpha,n)¹⁶O reactions (dotted brown line), and random coincidences (dashed purple line). Inset, expected spectra extended to higher energy. The geoneutrino spectra are calculated from our reference model, which assumes 16 TW radiogenic power from ²³⁸U and ²³²Th. The error bars represent plusminus 1 standard deviation intervals.
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Panel a shows the 68.3% confidence level (CL; red), 95.4% CL (green) and 99.7% CL (blue) contours for detected ²³⁸U and ²³²Th geoneutrinos. The small shaded area represents the prediction from the geophysical model. The vertical dashed line represents the value of (NU - NTh)/(NU + NTh) assuming the mass ratio, Th/U = 3.9, derived from chondritic meteorites, and accounting for the ²³⁸U and ²³²Th decay rates and the nu macre detection efficiencies in KamLAND. The dot represents our best fit point, favouring 3 ²³⁸U geoneutrinos and 18 ²³²Th geoneutrinos. Panel b shows Deltachi2 as a function of the total number of ²³⁸U and ²³²Th geoneutrino candidates, fixing the normalized difference to the chondritic meteorites constraint. The grey band gives the value of NU + NTh predicted by the geophysical model.
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Approximately 25% and 50% of the total flux originates within 50 km and 500 km of KamLAND, respectively. The line representing the crust includes both the continental and the almost negligible oceanic contribution.
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KamLAND can only detect electron antineutrinos to the right of the vertical dotted black line; hence it is insensitive to ⁴⁰K electron antineutrinos.
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Prompt energy spectrum with best-fit oscillation spectrum shown in solid black. The green bands indicate the systematic error. The grey histogram gives the unoscillated spectrum, the accidental spectrum is shown in orange, blue is spallation background and finally hatched light blue is the (a,n) background.
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Prompt- and delayed-event energy distribution.
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Confidence level bands for 2 neutrino oscillation KamLAND only. Best fit point is at Δm² = 7.9 x 10^-5 eV² and tan²θ = 0.46.
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Confidence level bands for a global fit to solar fluxes and KamLAND (2 neutrino oscillation analysis). Best fit point is at Δm² = 7.9^+0.6_-0.5 x 10^-5 eV² and tan²θ =0.40^+0.10_-0.07.
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Combination of the KamLAND-only contours and the global fit of KamLAND and solar fluxes (2 neutrino oscillation analysis).
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Confidence bands for 2 neutrino oscillation as measured by KamLAND. The green shaded region is the rate only 95% C.L. exclusion region.
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Confidence bands for 2 neutrino oscillation fit to the KamLAND spectrum only (the constraint of the overall rate has been removed). Best fit point is at Δm² = 8.0 x 10^-5 eV² and sin²2θ = 0.98.
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Time varyation of the expected no-oscillation nuebar flux at KamLAND.
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Event distribution in L₀/E, where L₀ is taken to be 180 km. The solid blue curve is the best fit oscillation spectrum. The two other curves show the dependence on L₀/E for two other neutrino disappearance hypothesis, decay and decoherence.
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Event distribution in L₀/E, where L₀ is taken to be 180 km. The solid blue curve is the best fit oscillation spectrum.
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Baseline distribution of the expected no-oscillation neutrino event rate at KamLAND.
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Fraction of volume inside the fiducial radius verified with spallation-produced B12 (assuming uniform distribution).
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Fraction of volume inside the fiducial radius verified with spallation-produced neutrons (assuming uniform distribution).
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Ratio of observed to expected anti-neutrino flux as a function of distance from nuclear reactors, including KamLAND. From 2002 PRL.

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Ratio of observed to expected flux as a function of detector distance for reactor experiments before KamLAND.

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Ratio of observed to expected flux as a function of detector distance for reactor experiments before KamLAND plus the solar LMA prediction.

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KamLAND Exclusion Plot from 2002 PRL.

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KamLAND Neutrino Energy Spectrum from 2002 PRL.

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Plot of energy of delayed neutron capture versus energy of prompt positron for selecting anti-neutrino events.

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Plot of energy of delayed neutron capture versus energy of prompt positron for selecting anti-neutrino events from 2002 PRL.

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Performance of Event Reconstruction from 2002 PRL.

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Detector Schematic as shown in 2002 PRL.

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KamLAND detector and experimental Site

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KamLAND detector 3-D Image

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Prompt positron event for first anti-neutrino candidate

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Delayed Neutron capture event for for first anti-neutrino candidate

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Stopped muon in KamLAND

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Cerenkov ring in buffer oil due to muon.

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A Michel electron following a muon.

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KamLAND detector schematic (detailed but not labeled)

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KamLAND detector (labeled)

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