Recent Results from Recent Results from KamLANDKamLAND

R. D. McKeownCaltechBNL – January 17, 2006

Outline

• Historical Introduction

Neutrino physics

Neutrino mixing and oscillations

• KamLAND reactor neutrino results

• Geoneutrinos

• Future prospects

Discovery of the Neutrino – 1956

F. Reines, Nobel Lecture, 1995

Subsequent History

• 60’s and 70’s – became the darling of accelerator-based particle physics

e ≠

• 1968 – 1st solar anomaly evidence• 1980’s – new interest in neutrino

oscillations (F. Reines, …..)

• 1980-present: the quest for neutrino oscillations

• 1998 – evidence from Super-K

Super-Kamiokande Results

Two Generation Model

1.24

(Pe minimum)

Missing solar neutrinos…

Matter Enhanced Oscillation (MSW)Mikheyev, Smirnov, Wolfenstein

Maki – Nakagawa – Sakata Matrix

CP violation

Pre – KamLAND summary

• Persistent observations of deficit of solar neutrinos

• 1998 – observation of oscillations of atmospheric neutrinos by Super-K

• 2002 – SNO results imply matter-dependent oscillations of solar neutrinos

Time to get our feet on the ground!!

W.A. Fowler Nobel Lecture,

1983

We need a “laboratory”Experiment!!

Enter

• Long Baseline (180 km)• Calibrated source(s)• Large detector (1 kton)• Deep underground (2700 mwe)

Neutrino Oscillation Studies with Nuclear Reactors

• e from n-rich fission products• detection via inverse beta decay (e+pe++n)• Measure flux and energy spectrum• Improve detectors, reduce background• Variety of distances L= 10-1000 m

Detection Signal

Coincidence signal: detect• Prompt: e+ annihilation EEprompt+En+0.8 MeV• Delayed: n capture 180 s capture time

p+e

511keV

511keV 2.2 MeV

d

n

~ 200 MeV per fission

~ 6 e per fission

~ 2 x 1020 e/GWth-sec

Reactor Isotopes

The Reactor Neutrino

Flux and Spectrum• 235U, 239Pu, 241Pu from measurements • 238U calculated• Time dependence due to fuel cycle

Precise Measurements

Flux and Energy Spectrum ~1-2 %

Reactors are calibrated sources of ’s !!

Negative Oscillation Searches

103

Distance (m)

The BIG picture: (From PDG)

SK atm ()

KamLAND usesthe entire Japanese

nuclear powerindustry as a

long baseline source

Kashiwazaki

Takahama

Ohi

Many reactors contribute to the antineutrino flux at KamLANDMany reactors contribute to the antineutrino flux at KamLAND**EEνν>3.4MeV >3.4MeV (E(Epromptprompt>2.6MeV)>2.6MeV)SiteSite Dist Dist

(km)(km)Cores Cores

(#)(#)

PPthermtherm

(GW)(GW)

FluxFlux

(cm(cm-2 -2 ss-1-1))

Rate Rate nooscnoosc**

(yr(yr-1-1 kt kt-1-1))Japan

Japan

KashiwazakiKashiwazaki 160160 77 24.324.3 4.1·104.1·1055 254.0254.0OhiOhi 179179 44 13.713.7 1.9·101.9·1055 114.3114.3TakahamaTakahama 191191 44 10.210.2 1.2·101.2·1055 74.374.3TsurugaTsuruga 138138 22 4.54.5 1.0·101.0·1055 62.562.5HamaokaHamaoka 214214 44 10.610.6 1.0·101.0·1055 62.062.0MihamaMihama 146146 33 4.94.9 1.0·101.0·1055 62.062.0SikaSika 8888 11 1.61.6 9.0·109.0·1044 55.255.2Fukushima1Fukushima1 349349 66 14.214.2 5.1·105.1·1044 31.131.1Fukushima2Fukushima2 345345 44 13.213.2 4.8·104.8·1044 29.529.5Tokai2Tokai2 295295 11 3.33.3 1.6·101.6·1044 10.110.1OnagawaOnagawa 431431 33 6.56.5 1.5·101.5·1044 9.39.3SimaneSimane 401401 22 3.83.8 1.0·101.0·1044 6.36.3IkataIkata 561561 33 6.06.0 8.3·108.3·1033 5.15.1GenkaiGenkai 755755 44 10.110.1 7.8·107.8·1033 4.84.8SendaiSendai 830830 22 5.35.3 3.4·103.4·1033 2.12.1TomariTomari 783783 22 3.33.3 2.3·102.3·1033 1.41.4S

outh

Kore

aSouth

Kore

a

UlchinUlchin 712712 44 11.511.5 9.9·109.9·1033 6.16.1

YonggwangYonggwang 986986 66 17.417.4 7.8·107.8·1033 4.84.8

KoriKori 735735 44 9.29.2 7.5·107.5·1033 4.64.6

WolsongWolsong 709709 44 8.28.2 7.1·107.1·1033 4.34.3

Total Total NominalNominal -- 7070 181.181.

771.3·101.3·1066 803.8803.8

Deta

iled

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uel

Deta

iled

pow

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d f

uel

Com

posit

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calc

ula

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used

Com

posit

ion

calc

ula

tion

used

From electrical From electrical powerpower

Japanese averageJapanese averagefuel usedfuel used

A limited range of baselines contribute to the fluxA limited range of baselines contribute to the fluxof reactor antineutrinos at Kamiokaof reactor antineutrinos at Kamioka

Korean reactorsKorean reactors3.4±0.3%3.4±0.3%

Rest of the worldRest of the world+JP research reactors+JP research reactors

1.1±0.5%1.1±0.5%

Japanese spent fuelJapanese spent fuel0.04±0.02%0.04±0.02%

Spectrum Distortion

Front End Electronics

Samples (~1.5ns)

AD

C c

ount

s (~

120

V)

Blue: raw datared: pedestalgreen: pedestal subtracted

Waveforms are recorded using Analog Transient Waveform Digitizers (ATWDs), allowing multi p.e. resolution

The ATWDs are self launching

with a threshold ~1/3 p.e. Each PMT is connected to 2

ATWDs, reducing deadtime Each ATWD has 3 gains (20,

4, 0.5), allowing a dynamic range

of ~1mV to ~1V

The KamLAND Collaboration

KamLAND:timelineKamLAND:timeline

•Summer 2000 PMT installationSummer 2000 PMT installation•Jun-Sept 2001 Fill Liquid ScintillatorJun-Sept 2001 Fill Liquid Scintillator•Jan, 2002 Begin Data TakingJan, 2002 Begin Data Taking• Dec, 2002Dec, 2002 Report 1st Physics Results Report 1st Physics Results• Jun 2004Jun 2004 Report 2nd Reactor Report 2nd Reactor Results Results• Sept 2005Sept 2005 Report geoneutrino evidenceReport geoneutrino evidence

Energy Determination & Resolution

E/E ~ 6.2% /√E , Light Yield ~ 300p.e./MeV

Esyst = 2.0% at 2.6 MeV

Tagged cosmogenics can be used for calibrationTagged cosmogenics can be used for calibration

1212BB

1212NN

Fit to data shows that12B:12N ~ 100:1

τ=29.1msQ=13.4MeV

τ=15.9msQ=17.3MeV

μ

Energy calibration uses discrete Energy calibration uses discrete γγ and and 1212B/B/1212NN

68Ge

65Zn

60Co

n-p

Carefully include Birks law, Cherenkov and light absorption/opticsCarefully include Birks law, Cherenkov and light absorption/opticsto obtain constants for to obtain constants for γγ and and ee–type depositions–type depositions

n-12C

σσ/E ~ 6.2% at 1MeV/E ~ 6.2% at 1MeV

z

Vertexing is performed using timing from the 17” PMTsVertexing is performed using timing from the 17” PMTs

-65 (1.1MeV)

-68 (1.0MeV)

-60 (2.6MeV)Am/Be(~8MeV)

neutronsneutrons

Fraction of volume Fraction of volume insideinside the fiducial radius verified the fiducial radius verifiedusing using μμ-produced -produced 1212B/B/1212N and n (assumed uniform)N and n (assumed uniform)

1212B/B/1212NN

Estimate of total volume and fiducial fractionEstimate of total volume and fiducial fraction

Singles Background

14C:? 210Pb: 102Hz:--

85Kr: 606 Hz:--

40K:1.9Hz:2.1Hz208Tl: 3.2Hz:1.4Hz

232Th, cosmogenic: 0.19Hz

High Energy (e.g. μ): 0.33Hz:0.33Hz

Source:Measured:Predicted

Radioactivity inside Liquid Scintillator

- R- Rprompt, delayedprompt, delayed < 5.5 m < 5.5 m

- - ΔΔRRe-ne-n < 2 m < 2 m

- 0.5 - 0.5 μμs < s < ΔΔTTe-ne-n < 1 ms < 1 ms

- 1.8 MeV < E1.8 MeV < Edelayeddelayed < 2.6 MeV < 2.6 MeV

- 2.6 MeV < E2.6 MeV < Epromptprompt < 8.5 MeV < 8.5 MeV

Tagging efficiency 89.8%Tagging efficiency 89.8%

… …In addition:In addition:

- 2s veto for showering/bad 2s veto for showering/bad μμ

- 2s veto in a R = 3m tube along track2s veto in a R = 3m tube along track

Dead-time 9.7%Dead-time 9.7%

Selecting antineutrinos, ESelecting antineutrinos, Epromptprompt>2.6MeV>2.6MeV

(543.7 ton)(543.7 ton)

5.5 m5.5 mfiducial cutfiducial cut

Balloon edgeBalloon edge

Observed Event Rates

2002-4 dataset 766.3 ton•yr, Eprompt > 2.6 MeV

Observed: 258 events

No-oscillation: 365.2 ± 23.7 events

Background 17.6 ± 7.2 events accidental 2.69 ± 0.02 9Li/8He (, n) 4.8 ± 0.9 fast neutron < 0.89 13C(,n) 10.0 ± 7.1

99.998% CL

Nobs – NBG

Nno-osc

= 0.658 ± 0.044 (stat) ± 0.047 (syst)

99.998 % C.L.

Evidence for Reactor e Disappearance!!

SystematicSystematic %%

Scintillator volumeScintillator volume 2.12.1

Fiducial fractionFiducial fraction 4.24.2

Energy threshold Energy threshold 2.32.3

Cuts efficiencyCuts efficiency 1.61.6

Live timeLive time 0.060.06

Reactor PReactor Pthermalthermal 2.12.1

Fuel compositionFuel composition 1.01.0

Time lagTime lag 0.010.01

Antineutrino Antineutrino spectrumspectrum 2.52.5

Antineutrino x-Antineutrino x-sectionsection 0.20.2

TotalTotal 6.56.5

Ratio of Measured and Expected e Flux from Reactor Neutrino Experiments

Solar : m2 = 5.5x10-5 eV2

sin2 2 = 0.833

G.Fogli et al., PR D66, 010001-406,(2002)

Oscillation Effect

Time Variations of Reactor Power and

Signals

Correlation with reactor power variation

KamLAND best fit : m2 = 7.9 x 10-5 eV2

tan2= 0.45

• Neutrino Mixing• Neutrino Masses• Flavor Oscillations

+

Combined fit with solar neutrino data

m2=7.9+0.6-0.5x10-5 eV2

tan2=0.40+0.10-0.07

Open circles: combined best fitClosed circles: experimental data

Solar Neutrino Results

Geoneutrinos – the early history

More recent references

Geoneutrinos

• U/Th/K in crust/mantle- amount of activity- distribution

• Energy budget – heat generation- plate tectonics- magnetic field

• Structure of earth’s core- constrain models- georeactor?

Inside the Earth

Region Thickness (km )

Continental crust 38 (20 – 70)

Oceanic crust 6-8

Upper Mantle 600

Lower Mantle 2300

Core 3500

U/Th Distribution

Geoneutrino spectrum

The predicted sources of geoneutrinos

KamLAND Data

UTh

Reactor

13C(,n)

Randoms

Confidence Intervals

The press was interesting…

Hindustan Times, August 8, 2005

And finally:

KamLAND Future

• Precision Reactor Neutrino Measurements- 4calibration system- refine analysis methods- more statistics

•Supernova detection• Precision Solar Neutrino Measurements

- radiopurity- low energy threshold

• More precise geoneutrino measurement

Neutrino-proton elastic scattering

e e

, ,,