Exploring the earth and the sun with neutrinos

The 21st Century COE Program of Tohoku University Symposium “Exploring New Science by Bridging Particle-Matter Hierarchy” 4-5 March 2005

Research Center for Neutrino ScienceKunio Inoue

Motivationswith my amateur knowledge

The earth has formed by acretion of small

astronomical objects such as grain or meteorite.

Heavy nickel and iron sank and light silicon went up in the molten protoearth and the layer structure was formed.

Heat account is important to understand

the bulk silicate earth formation.

The Earth

Terrestrial magnetic field, protecting lives from solar wind, is caused by a core movement.It requires some heat source.

Terrible earthquakes, eruptions etc. are originally

caused by mantle convection driven by heat.

Surface heat flow is estimated by extrapolating local heat

gradient measurements to the entire surface.

One popular estimation: 44 TWRecent estimation : 34 TW

This important geophysical parameter is not quite well understood.

More uncertain estimation from CI Chondrite (chemical composition is close to the original grains)

tells 20 TW comes from radioactivity in the earth.

Uranium : 8TW, Thorium : 8TW, Potassium : 4TW

Direct measurement is desired!! HOW??

Possible windows to the interior of the earth

Detailed seismic analysis gives precise velocity distribution.

Very deep boring may reach the upper mantle.

However, it doesn t tell chemical composition.

However, it s only up to 7 km.

Phase studies at high pressure and temperature,solubility studies are all in Laboratory .

density/viscosity

Analyses of eruptions, magnetic field measurement provide imformation.

However, it s not very conclusive for the global structure.4000m(sea depth)+7000m (boring)

Ocean Drilling Chikyu

A model assumes driving heat is 75% from radioactivity and

25% from outer core.

Do upper and lower mantle have homogeneous chemical

composition?

Geo-chemist

Geo-physicist

Two layer or whole mantle convection is still a long-standing argument.

238U series

232Th series

238U →206 Pb + 84He + 6e− + 6ν̄e + 51.7 MeV

232Th →208 Pb + 64He + 4e− + 4ν̄e + 42.7 MeV

endpoint 3.27 MeV

endpoint 2.25 MeV

40K

endpoint 1.31 MeV40K + e− →40 Ar + νe

40K →40 Ca + e− + ν̄e

Anti-electron-

neutrinos are

emitted.

future interest

simulations

Geo-reactor?Why does terrestrial magnetic field flip every million years?3He/4He relative to air (95% CL)

New exotic hypothesis Geo-reactor may explain those.

Uranium sink and exceed

critical density.

Nuclear fission feeds power for magnetic

field.

Fuel burns out and reactor stops.

Magnetic field

collapses.

Why do volcanic lava and basalt of Hawaii and Iceland contain 3He?What is the mechanism?

玄武岩

The Sun

visible UV X-ray

4p → α + 2e+ + 2νe + 26.73 MeV

The sun is shining with fusion reaction at the very center. Optical observation doesn t provide direct information of it.

Photons spend ̃one million years to emerge while neutrinos take only 2.3 sec.

This conclusion is an outcome of great success

of nuclear physics. (nuclear cross section, opacity etc.)

€

p+12C→13N +γ

€

13N→13C +e+ + ν e

€

p+13C→14 N +γ

€

15O→15N +e+ + ν e

€

p+14 N→15O +γ

€

p+15N→12C +α

€

p+15N→16O +γ

€

p+16O→17F +γ

€

17F→17O +e+ + ν e

€

p+17O→14 N +α

€

~ 4 ×10-4

The CNO cyclepp chain(pp-chain) 98.5%

€

D p→3Heγ

€

3He 4He→7Beγ

€

3He 3He→4He p p

13.8%

84.7%

€

7Bee−→7Liν e (γ)(7Be)

€

7Be p→8Bγ

€

p p→De+ν e

€

pe− p→ Dν e(pp) (pep)

99.77% 0.23%

~2×10-5%

13.78% 0.02%

€

7Li p→4He 4He

€

3He p→4He e+ν e(hep)

€

8B→8Be* e+ν e

€

4He 4He(8B)

7Be ~14% 8B ~0.02%

Originally, two possibilities were considered.

Pioneering Davis (Novel laureate with Koshiba)

experiment was aiming at discriminating these.

However, it was a start of the solar neutrino problem .

The problem has lasted more than 30 years until KamLAND.

Correct knowledge of neutrino propagation is indispensable for the Neutrino Astrophysics !

SK, SNOChlorineGallium

10

102

103

104

105

106

107

108

109

1010

10-1

1 10

[MeV]

hep

8B

pep

7Be

7Be

pp

13N

15O

17F

1011

1012

1013

[/MeV/cm2/sec]

±1%

±12%±12%

±2%

±23%

±16%∼ ±40%

Model prediction

Low energy neutrino observation is desired for cross check of the standard solar model.

tan2(!)

"m

2 in

eV

2

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-4

10-3

10-2

10-1

1 10 102

Ga

Cl

SuperK

SNO

SMA

LOW

VAC

LMAIf one assumes neutrino oscillation hypothesis, the LMA solution is the most favorable.

The other hypotheses,Neutrino magnetic moment,flavor changing interaction,neutrino decay,neutrino decoherence,CPT violationetc. are also remaining.

Further investigation with well-understood man-made neutrinos is desired.

Neutrino oscillation parametersconsistent with each observations

€

ν e

ν µ

=

cosθ sinθ−sinθ cosθ

ν1ν 2

m1 != m2

Ne

mν2

ν1

νµ

νe

P (νe → νµ) " sin2 2θ sin2(∆m2t

4E)

! sin2 2θ sin2(1.27∆m2(eV2)L(m)

E(MeV))

In matter (in the sun)

In vacuum

Neutrinos

Electron kinetic energy (MeV)

Relat

ive in

tens

ity

210Bi

Reines CowanNeutrinos rarely interact with matter.

Typical reactor neutrino energy is ̃4MeV.

Cross section at the energy is

In case of water target, interaction length is ̃20 light years.

Sun Mercury MarsEarthVenus

Jupiter Saturn Uranus Neptune Pluto

× ∼ 1000

Strong neutrino source and huge detector are indispensable.

∼ 7 × 10−43 cm2

ν̄e + p → e+ + n

1956 First discovery with reactor neutrinos.

1930 Theoretical prediction

Why did it take so much time?

PauliNeutrino?

Probability that the reaction takes place in Poltergeist was only . ∼ 11017

New particle !

Project Poltergeist

Qua

rks u

d

cs

t

b

Lept

ons

eνe νµ ντ

µ τ

γ

g

Z

WFo

rce

carr

iers

Mat

ter P

artic

les

All ordinary matter belongs to this generation.

Where do neutrinos come from?

atmosphere

supernova

The sunBig bang

300ν/cm3

nuclear reactor acceleratorU

Th U

Th

Th

UUTh Th

radio-activities in the earth

human body

(Kamioka)

(geo-neutrino)

66 billion νe/cm2/sec300 million /day

6 million ν̄e/cm2/sec

First of all, we have to understand

neutrino propagation for the exploration

of the earth and the sun.

Man-made neutrinos are good choice.

accelerator commercial reactor

π+ → µ+ + νµetc.

235U + n → X + Y + 6.1e− + 6.1ν̄e + 2.5n + 202 MeV239Pu, 238U, 241Pualso

No chargeexpensive

Reactor neutrino detection

prompt signal

delayed signal

with a help of inverse reaction

ν̄e + p → e+ + n

n + p → d + γ(2.2 MeV)

e+ + e− → 2γ

τ ∼ 210 µsec

Eth =(Mn + me)2 − M2

p

2Mp= 1.806 MeV

Evis ∼ Eν − 0.78 MeV> 1.022 MeV

ν̄e ~99.999% (E > 1.8 MeV)

n → p + e− + ν̄e

σ(ν̄ep) is calculable at 0.2% accuracy.

σ(0)tot =

2π2/m5e

fRp.s.τn

E(0)e p(0)

e

τn = 885.7 ± 0.8 sec

P.Vogel and J.F.Beacom, Phys.Rev.D60(1999)053003

A.Kurylov et al., Phys.Rev.C67(2003)035502

10-5

10-4

10-3

10-2

10-1

1

0 1 2 3 4 5 6 7 8 9 10

Energy (MeV)

neutr

inos/M

eV

/fis

sio

n

238U

239Pu

235U

241Pumeasured at ILL

30 hypothetical beta fitK.Schreckenbach et al., Phys.Lett.B160(1985)325

A.A.Hahn et al., Phys.Lett.B218(1989)365

theoretical 744 tracesP.Vogel et al., Phys. Rev. C24(1981)1543

M.F.James, J.Nucl.Energy 23(1969)517

235U : 201.7, 238U : 205.0, 239Pu : 210.0, 241Pu : 212.4 MeV

∼ 2 × 1020 ν̄e/GWth/sec

Status before KamLANDOscillation Search up to 1 km baseline

Nobs

/Nn

oosci

.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

10 102

103

!"#$%&'$ ()*

+,,-.$#/$'0"1"''"2 3&1$4!5/$63.1'.74"#'.6"4#8

92..:;"%. <$4=$

2

KamLAND

Chooz, 98

Palo Verde, 00

Goesgen, 86

ILL, 81

Rovno, 88

Bugey 3, 96

Savanna hRiver, 86

1% per

year

10% per

year

Neutrino Mass ( m ) sensitivity ( eV )

10 10 10 101 10

10

10

10

10

10

-1 -2 -3 -4 -5

2∆

10 m 100 m 1 km 10 km 100 kmBaseline

0

2

4

6

8

1010

thR

eact

or P

ower

x T

arge

t Mas

s (M

W

ton

)

P (ν̄e → ν̄e) = 1 − sin2 2θ sin2(1.27 × ∆m2(eV 2)L(m)E(MeV )

)

Ereactor ∼ 5MeV

νatm νsol

More than 100km baselines is necessary to explore the LMA solution.

Powerful reactor, Big detector, Deep underground

120˚W 90˚W 60˚W 30˚W 0˚ 30˚E 60˚E 90˚E 120˚E 150˚E

45˚S

30˚S

15˚S

0˚

15˚N

30˚N

45˚N

60˚N

Europe

Africa

North America

South America

Asia

West Asia

East Asia

Russia

Europe

Africa

North America

South America

Asia

West Asia

East Asia

Russia

International Nuclear Safety Center at ANL, Oct 2002International Nuclear Safety Center at ANL, Oct 2002

Total power generation with nuclear reactors in the world amounts to ~1.1 TWthermal.

It corresponds to ~2x1023 creations/sec.

Where is a powerful reactor?

ν̄e

EuropeNorth AmericaJapanAsia w/o JapanOthers

521 GW333 GW152 GW60 GW11 GW

It is Kamioka!

~97% from Japan~2.5% from Korea

from

200

6 LMA parameters

70 GW (7% of world total) is generated at 130-240 km distance from Kamioka.

Reactor neutrino flux,requires O(kiloton) underground detector.

∼ 6 × 106/cm2/sec

If we pay for the electricity, it is ̃70 million $/day.

Orders of magnitude improvements

Poltergeist KamLANDThe 1st neutrino experiment in 1956 The latest reactor experiment

Reactor Power 700 MW 70 GW ×1001400 litter LS 1200 m3 LS ×1000

Depth 12 m 1000 m ×100

Distance11 m ~180 km ×10000

3 sec jog 3 hour drive

Detector Size

This is the right distance to explore the LMA solution.

This extension becomes possible by many important improvements on knowledge of reactor neutrinos by previous experiments.

Going higher?

Hubble space telescopeSubaru telescope at the summit of Mauna Kea

No! Digging underground.

Where to go?

On the ground,interaction rate of muons with one’s body is ~100 /sand of neutrinos is ~1/week.1,000m rock reduces muonrate by factor 100,000 but no reduction for neutrinos.

1,000m rock

ground level

Does a mole here sees neutrinos?

mainly low energy solar neutrinos

He has to overcome radioactive impurities and target mass.

BG muon intensity

ν-scop

e

1000m

There was a retired detector, Kamiokande and new much bigger Super-Kamiokande was running 200m apart from it.

Tohoku university took over the former Kamiokande place and built a new liquid scintillator detector, KamLAND.

KamLAND = Kamioka Liquid scintillator Anti-Neutrino Detector

16m

20m

Kamiokande KamLAND

KamLAND

KamLAND 18mφ stainless tank

O

N

1.5g/l

HHHHHHHHHHHHHCCCCCCCCCCCCHHHHHHHHHHHHH

80%

CH3CH3

CH320%

LS

Water Cherenkov Outer Detector

LS

Buffer Oil

photo-coverage22% --> 34%

BO50% dodecane50% isoparaffin

KamLAND1000m

1200 m3

1800 m3

20m

3200 m3

ρ = 0.78 g/cm3

8000 photons/MeV

λ ∼ 10 m

ρLS

ρBO= 1.0004

∼ 500 p.e./MeV

1325 17”-PMTs+

554 20”-PMTs(since Feb 2003)

1 wash by detergent rinse with pure water polish with alcohol goto 1 stop end

The best cleaning tools we’ve found are a kitchen sponge and a kitchen detergent (MagicleanTM).

A fortran program loaded on us

Total hand movement during the scrub is

~1000km!

PMT installation has been completed in September 2000.

!"#!$%&'#"

%(!)'!$%&'#"

$%(*&!$%&'#"

+,-!)".#-'/0#"

!)"#-0*'#"

0*'#"-#1'"*2'%/(

+,

The world cleanest detector

Ions are billion times more solvable to water.Wash scintillator with pure water.

Achievement is 238U 3.5×10−18g/g232Th 5.2×10−17g/g

It is trillion times cleaner than ordinary material (~1 ppm)or 100 times cleaner than Super-Kamiokande.

0.4 1.0 2.6 8.5 Visible energy　[MeV]

Neutrino Astrophysicsverification of SSM

Neutrino Geophysicsverification of earth

evolution model

Neutrino PhysicsPrecision measurement of oscillation parameters

Neutrino Cosmologyverification of

universe evolution

7Be solar neutrino geo-neutrino reactor neutrino supernova relic neutrinoetc.

Various Physics Targetswith wide energy range

1st results PRL 90, 021802 (2003)2nd results PRL 94, 081801(2005)

Solar PRL 92, 071301 (2004)

ν̄eforthcomingfuture2nd phase

neutrino electron elastic scatteringinverse beta decayν + e− → ν + e− ν̄e + p → e+ + n

Kashiwazaki Kariwa, 25 GW the world strongest reactor complex

Reactor Neutrino Analysis

0.4 1.0 2.6 8.5 Visible energy　[MeV]

Neutrino Astrophysics

verification of SSM

Neutrino Geophysics

verification of earth

evolution model

Neutrino Physics

Precision measurement

of oscillation parameters

Neutrino Cosmology

verification of

universe evolution

7Be solar neutrino geo-neutrino reactor neutrinosupernova relic neutrino

etc.

neutrino electron elastic scatteringinverse beta decayν + e− → ν + e− ν̄e + p → e+ + n

Jul/02 Jan/03 Jul/03 Jan/04

(even

ts/d

ay)

no

-osc

il

exp

N

0

0.2

0.4

0.6

0.8

1

1.2

Wei

ghte

d d

ista

nce

(km

)

150

160

170

180

190

200

210

no-oscil

expN

Weighted distance

Period for first result

1st result4 Mar 2002 - 6 Oct 2002

145.1 days

2nd result9 Mar 2002 - 11 Jan 2004

515.1 days

Detailed information from Japanese reactorsHistory of electric power output from Korean reactorsNominal power from the other reactors

95.5%3.4%1.1%

Available information Contribution

Reactor data

Data Summaryfrom March 4 to October 6, 2002

145.1 live days, 162 ton-year exposure

Analysis threshold 2.6 MeVexpected signal

BGobserved

86.8 ± 5.6

54Neutrino disappearance at 99.95% CL.

R = 0.611 ± 0.085(stat) ± 0.041(syst)

KamLAND collaboration, Phys.Rev.Lett.90(2003)021802

1 ± 1

1st result

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0 N

ob

s/N

no

_o

scil

lati

on

101

102

103

104

105

Distance to Reactor (m)

ILL Savannah River Bugey Rovno Goesgen Krasnoyarsk Palo Verde Chooz

KamLAND

Evidence for reactor neutrino disappearance

2 gen. Neutrino oscillation parametersconsistent with each solar results

with KamLAND rate

RSFPFCNCdecay

decoherenceetc.

tan2(!)

"m

2 in

eV

2

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-4

10-3

10-2

10-1

1 10 102

Ga

Cl

SuperK

SNO

LMA

SMA

LOW

VAC

LMA

SMA

LOW

RSFPFCNCdecay

decoherenceetc.

VAC

Reactor neutrino disappearance excluded all but LMA from leading phenomena.

Data Summaryfrom 9 Mar 2002 to 11 Jan 2004

515.1 live days, 766.3 ton-year exposure

expected signalBG

observed

Neutrino disappearance at 99.998% CL.

KamLAND collaboration, hep-ex/0406035

365.2 ± 23.7

258

for Mar to Oct 2002is consistent with first results

2nd resultData Summaryfrom March 4 to October 6, 2002

145.1 live days, 162 ton-year exposure

expected signalBG

observed

86.8 ± 5.6

54Neutrino disappearance at 99.95% CL.

KamLAND collaboration, Phys.Rev.Lett.90(2003)021802

1st result

×4.7 exposure (×3.55 live time, ×1.33 fiducial)

17.8 ± 7.3

R = 0.658 ± 0.044(stat) ± 0.047(syst)

R = 0.601 ± 0.069 ± 0.042

R = 0.589 ± 0.085(stat) ± 0.042(syst)with new background correction

2.8 ± 1.7

24

Time Dependence of Expected and Observed Event Rates

Time Dependence of Expected and Observed Event Rates

expected (no oscillation)

observed

追加

Event list and relevant numbers are available at http://www.awa.tohoku.ac.jp/KamLAND/datarelease/2ndresult.html

rate (events/day)e!no-osc

0 0.2 0.4 0.6 0.8 1 1.2

rat

e (e

ven

ts/d

ay)

e!

obse

rved

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.20

0.2

0.4

0.6

0.8

1

1.2

Data

Background

09 Mar '02 19 Oct '02 31 May '03 11 Jan '04

rate

(ev/d

)e!

no-o

sc

0.3

0.6

0.9

1.2

Correlation with reactor power

95% CL

χ2/dof = 2.1/4constrained to expected BG

no os

cillati

on

χ2flat = 5.4

data division scheme

Current statistics is not enough to say definite thing.

Geo-reactor? {

Prompt Energy (MeV)

Even

ts/0

.42

5M

eV

KamLAND datano oscillation

scaled no osc.accidental

0 2 4 6 80

20

40

60

80

spectral distortion at >99.6% CLrate + shape 99.999995% CL

hypothesis test of scaled no oscillation

for 20 equal probability bins

goodness of fit (MC)0.4%

Energy Spectrum

χ2/dof = 37.3/19

oscillation

Best fit parameters χ2/dofModel GOF11.1%

decay 0.7%decoherence 1.8%

Significant spectral distortion supports neutrino oscillation.

equal probability 20 bins MC basedby unbin-likelihood method

Prompt Energy (MeV)

Even

ts/0

.425M

eV

KamLAND data

no oscillation

best-fit oscillation

accidental

O16

, n)!C(13

0 1 2 3 4 5 6 7 80

20

40

60

80

(sin2 2θ,∆m2) = (0.86, 7.9 × 10−5 eV2)

35.8/1732.2/17

24.2/17

(sin2 2θ, γ) = (1.0, 0.030 MeV/km)

(sin2 θ,m2/cτ) = (1.0, 0.011 MeV/km)

0 20 30 40 50 60 70 80

/E (km/MeV)0

L

Rat

io

2.6MeV

analysis threshold

KamLAND data

best-fit oscillation

best-fit decay

10

0.2

0.4

0.6

0.8

1

1.2

1.4

10-3

10-2

10-1

1

ILL

Goesgen

Savannah River

Palo Verde

CHOOZ

Bugey

Rovno

Krasnoyarsk

best-fit decoherence

oscillationdecay

decoherence

Pee = 1 − sin2 2θ sin2(∆m2

4L

E)

Pee = (cos2 θ + sin2 θ exp(−m2

2τ

L

E))2

Pee = 1 − 12

sin2 2θ(1 − exp(−γL

E))

L0=180km is used for KamLAND

ideal oscillation pattern

with real reactor

distribution

Clear oscillation pattern has been seen.

Measurement of neutrino oscillation parameters〈mνe〉 <

⟨mνµ

⟩ 〈mνe〉 >⟨mνµ

⟩matter effect makes small difference

10-1

1 10

10-5

10-4

!2tan

)2

(eV

2m

"

Solar

95% C.L.

99% C.L.

99.73% C.L.

solar best fit

KamLAND

95% C.L.

99% C.L.

99.73% C.L.

KamLAND best fit

best fit rate+shape(tan2 θ,∆m2) = (0.46, 7.9 × 10−5 eV2)

0.2 0.3 0.4 0.5 0.6 0.7 0.85

6

7

8

9

10

11

12

-510!

"2

tan)

2 (

eV2

m#

KamLAND + Solar

95% C.L.

99% C.L.

99.73% C.L.

global best fit

∆m2 = 7.9+0.6−0.5 × 10−5 eV2

tan2 θ = 0.40+0.10−0.07

several orders -> less than 10%

Precise determination of oscillation parameters made possible to use neutrinos as a new probe.

Assuming CPT invariance

0.4 1.0 2.6 8.5 Visible energy　[MeV]

Neutrino Astrophysics

verification of SSM

Neutrino Geophysics

verification of earth

evolution model

Neutrino Physics

Precision measurement

of oscillation parameters

Neutrino Cosmology

verification of

universe evolution

7Be solar neutrino geo-neutrino reactor neutrinosupernova relic neutrino

etc.

neutrino electron elastic scatteringinverse beta decayν + e− → ν + e− ν̄e + p → e+ + nGeo-neutrinos

Next targets

Low energy solar neutrinos

Moho Depth (Crust2.0 + Zhao1992)

-0.2 -0.1 0 0.1 0.2-0.2

-0.1

0

0.1

0.2

Moho Depth (Crust2.0 + Zhao1992)

0

5

10

15

20

25

30

35

40

Moho Depth (Crust2.0 + Zhao1992)

-0.2 -0.1 0 0.1 0.2-0.2

-0.1

0

0.1

0.2

Crust thickness

Japan Geology (Surface Exposure) - Rock Type -

130 132 134 136 138 140 142 14430

32

34

36

38

40

42

44

Japan Geology (Surface Exposure) - Rock Type -

0

1

2

3

4

5

Japan Geology (Surface Exposure) - Rock Type -

130 132 134 136 138 140 142 14430

32

34

36

38

40

42

44

Japan Geology (Surface Exposure) - Rock Type -

Longitude [deg]

Latitu

de [deg]

130 132 134 136 138 140 142 14430

32

34

36

38

40

42

44

Japan Geology (Surface Exposure) - Rock Type -

0

1

2

3

4

5

Geological map

Precise measurement of oscillation parameters

geo-neutrino observation

investigation of heat source Study of earth dynamics

KamLAND detector

KamLAND dataStudy of earth structurefeed back from geophysics information

“Neutrino geophysics”

Reactor neutrinoGeo-neutrino

(pp-chain) 98.5%

€

D p→3Heγ

€

3He 4He→7Beγ

€

3He 3He→4He p p

13.8%

84.7%

€

7Bee−→7Liν e (γ)(7Be)

€

7Be p→8Bγ

€

p p→De+ν e

€

pe− p→ Dν e(pp) (pep)

99.77% 0.23%

~2×10-5%

13.78% 0.02%

€

7Li p→4He 4He

€

3He p→4He e+ν e(hep)

€

8B→8Be* e+ν e

€

4He 4He(8B)

7Be ~14% 8B ~0.02%

Solar neutrino observationSK, SNOChlorineGallium

10

102

103

104

105

106

107

108

109

1010

10-1

1 10

[MeV]

hep

8B

pep

7Be

7Be

pp

13N

15O

17F

1011

1012

1013

[/MeV/cm2/sec]

±1%

±12%±12%

±2%

±23%

±16%∼ ±40%

KamLAND

Branching ratio to 7Be neutrino is larger and theoretical uncertainty is smaller.

Its flux is so far measured at only 40% level.

1104∼5

110∼6

requiredfurther improvement

For future physics

Background now goal

238U(by Bi-Po) 3.5× 10−18g/g OK!!

238U(by 234Pa) O(10−15g/g)(Max.) 10−18g/g

232Th (by Bi-Po) 5.2× 10−17g/g OK!!

40K 2.7× 10−16g/g(max.) < 10−18g/g

210Pb ∼ 10−20g/g 5× 10−25g/g ∼ 1µBq/m3

85Kr, 39Ar 85Kr =0.7Bq/m3 1µBq/m3

222Rn 238U = 3.5× 10−18g/g OK!! (1µBq/m3)

(after purification) = 3.3× 10−8Bq/m3

222Rn 1mBq/m3

(during purification) 210Pb = 0.5µBq/m3 after decay

4

Visible Energy (MeV)

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Ev

en

ts/M

eV

/se

c

10-4

10-3

10-2

10-11

10

102

103

104 Current background level

7Be νpp ν

14C

11C

85Kr210Bi210Po

daughter of 210Pb

SSM

Purification achievement◦N2 gas purge　　N2/LS=25 ---> ~1/10 Rn, ~1/100 Kr

◦Fractional Distillation (164℃, 300 hPa)　　 3×10-5 Pb　　 1×10-5 Rn　　<2×10-6 Kr　　Residual impurities will be some organic lead 　　(e.g. tetra-ethyl-lead) and they disintegrate at ~200 ℃.

Required performance is almost achieved.

0

50

100

150

200

250

300

350

400

450

500

400 450 500 550 600 650 700 750

even

ts/k

eV

Energy [keV]

KamLAND (expected 3y, R<4m)

7Be !

210Bi

LMA

After statistical subtruction (238

U, 232

Th) and assume all BG =

210Bi(

210Pb)

40000

60000

80000

20000 30000

7B

e !

210Bi

SSM

+/-3.6%(99%C.L)

0

5000

10000

15000

20000

25000

30000

0 0.2 0.4 0.6 0.8 1

cou

nts

[3

50

-75

0k

eV]

L02/L

2

KamLAND expected (5y, fiducial R<4m)

SUN

L; distance from Sun to Earth L=L0(1-!cos(2"t)), !=1.7%

Extrapolate L#!$ to estimate BG

SSM

LMA

result from L#!$ limit

0.00.20.40.60.81.01.2

SSM

LMA

BG subtraction with shape fit BG subtraction with seasonal variation

0

500

1000

1500

2000

2500

3000

0 200 400 600 800 1000

counts

/25keV

Energy [keV]

KamLAND future goal

14C

(assume 14

C/12

C=10-18

)

232Th(5.2x10

-17g/g)

11C

(1.0x103 day

-1kton

-1)

7Be !(SSM)

210Pb

(assume 1!Bq/m3)

39Ar,

85Kr

(assume 1!Bq/m3)

All

All ! (SSM)

When the required reduction is achieved,7Be neutrinos will be seen in the window

between 14C and 11C background.

accurate robust

Thank you!

The KamLAND collaborationTohoku + 11 US + 1 Chinese + 1 French institutes