日本物理学会　第６０回年次大会　東京理科大学野田キャンパス　2005年3月25日

カムランド実験の最近の結果

東北大学ニュートリノ科学研究センター井上邦雄

Motivationswith my amateur knowledge

Exploring interior of the Sun and the earth

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 : 31 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 MeV

40K + 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(Θ)

Δm

2 in e

V2

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 10 2

Ga

Cl

SuperK

SNO

SMA

LOW

VAC

LMA

If 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

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

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)

!"#!$%&'#"

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

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

+,-!)".#-'/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

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 10Energy (MeV)

neut

rinos

/MeV

/fiss

ion

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

~95.5% from Japan~3.5% from Korea

70 GW (7% of world total) is generated at 130-220 km distance from Kamioka.

from

200

6 LMA parameters

Neutrino oscillation study with spread reactors

effective distance ~180km(weighted average by event rate up to 400 km)

∼ 6 × 106/cm2/secReactor neutrino flux,

(2nd result period)

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

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(Θ)

Δm

2 in e

V2

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 10 2

Ga

Cl

SuperK

SNO

LMA

SMA

LOW

VAC

LMA

SMA

LOW

RSFPFCNCdecay

decoherenceetc.

VAC

Reactor neutrino disappearance excluded all but LMA from leading phenomena.

Background summary

Accidental Coincidence 2.69 ± 0.02

Spallation eventsFast neutron13C(α,n)16O

4.8 ± 0.9

< 0.9

10.3 ± 7.1

Total 17.8 ± 7.3

515.1 days, >2.6MeV, 5.5m fiducial

Day’01Dec31 ’02Dec31 ’04Jan01

rate

[H

z]

0

20

40

60

80

100

120

140

/ ndf 2! 15.4 / 28

Prob 0.9739

0Pb

N 5.097e+10± 6.863e+12

0

t 1.443e+06± 1.329e+08

/ ndf 2! 15.4 / 28

Prob 0.9739

0Pb

N 5.097e+10± 6.863e+12

0

t 1.443e+06± 1.329e+08

KamLAND filling (May-Sep. 2001)

210Po , all volume

222Rn (3.8d)218Po214Pb

214Bi214Po210Pb (22.3y)

210Bi (5.013d)

210Po (138.4d)206Pb (stable)

equilibrium

(Eα = 5.3MeV )

Visible Energy (MeV)

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Even

ts/M

eV

/sec

10-4

10-3

10-2

10-11

10

102

103

104

85Kr210Po

210Bi

Low energy spectrum

NsumMax40 60 80 100 120 140 160 180 200

Coun

ts

2000

4000

6000

8000

10000

12000

14000

16000

18000210Po

Prompt Energy [MeV]1 2 3 4 5 6 7 8

ev

en

t /

0.4

25

Me

V

05

10

15

2025

30

35

40

4550

10.3±7.1 events1.1% abundance (measured)

13C(α,n)16O ∼ 10−7

17O

16O + n

210Po αmax

internal pair conversion

6.36

4.14

0.87

3.063.844.55

6.056.136.92

γ

13C(α,n)16O(g.s.)

13C(α,n)16O∗(6.05)

13C(α,n)16O∗(6.13)

→12 C(n,nγ)12C

13C(α,n)16O(g.s.)

Cross check of production rate can be done using events below 1MeV.

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? {

Recent extensive inspection may provide another chance to investigate the correlation.

20

02

-04

20

02

-05

20

02

-06

20

02

-07

20

02

-08

20

02

-09

20

02

-10

20

02

-11

20

02

-12

20

03

-01

20

03

-02

20

03

-03

20

03

-04

20

03

-05

20

03

-06

20

03

-07

20

03

-08

20

03

-09

20

03

-10

20

03

-11

20

03

-12

20

04

-01

20

04

-02

20

04

-03

20

04

-04

20

04

-05

20

04

-06

20

04

-07

20

04

-08

20

04

-09

20

04

-10

20

02

-04

20

02

-05

20

02

-06

20

02

-07

20

02

-08

20

02

-09

20

02

-10

20

02

-11

20

02

-12

20

03

-01

20

03

-02

20

03

-03

20

03

-04

20

03

-05

20

03

-06

20

03

-07

20

03

-08

20

03

-09

20

03

-10

20

03

-11

20

03

-12

20

04

-01

20

04

-02

20

04

-03

20

04

-04

20

04

-05

20

04

-06

20

04

-07

20

04

-08

20

04

-09

20

04

-10

)2

MW

/cm

-12

Ele

ctr

ic p

ow

er

flu

x (

10

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1-10

10!

Electric power flux at KamLAND

0

1

2

3

4

5

6

7

8

9

10

JAIF data

2nd result

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

Prompt Energy (MeV)

Ev

ents

/0.4

25

MeV

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

GOF 11.1%

24.2/17

χ2/dof

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

98.0%

97.5%

62.1%

sin2 2θ = 0.6

0 20 30 40 50 60 70 80

/E (km/MeV)0

L

Rat

io

2.6MeV

analysis threshold

KamLAND data

best-fit LMA1

LMA2

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

LMA1 small mixing

reactor+geo combined analysis will provide new data points

Karsten Heeger, LBNL Sendai, September 20, 2003

Development and Testing of an Off-Axis

Calibration System for KamLAND

KamLAND 4! GroupLawrence Berkeley National Laboratory

It’s being built!

Further improvement of systematic errors

z-axis calibration

full volume calibration

Rate information doesn’t have a strong impact on

the precision due to large systematic errors.

rate+shape

best fit

shape only

best fit

0 0.2 0.4 0.6 0.8 110

-6

10-5

10-4

10-3

! 22

sin)

2 (

eV

2 m

"0 0.2 0.4 0.6 0.8 1

10-6

10-5

10-4

10-3

! 22

sin

)2

(eV

2 m

"

(0.86, 7.9 × 10−5) (0.98, 8.0 × 10−5)

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

(eV

2m

#

KamLAND + Solar

95% C.L.

99% C.L.

99.73% C.L.

global best fit

3% rate error 1% scale error 3kt-yr data accumulation

KamLAND onlyrate+shape sensitivity

(rough estimation)

capability to reject full mixing

mixing angle determination comparable with current solar data

fact

or ~

2 im

prov

emen

t?

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

95% can be reduced by tagging neutron.pep+CNO may be extractable.

SummaryUpdated results strengthened evidence of neutrino disappearance.

Spectral distortion is observed at >99.6% CL.

Rate+shape data excluded no oscillation at 99.999995% CL.

L/E plot shows clear oscillatory behavior.

Oscillation parameters are measured precisely.

Forthcoming geo-nu observation will pioneer “Neutrino geo-physics”.

KamLAND will push forward “Neutrino Astrophysics” with 7Be solar neutrino observation.

(1)

(2)

(3)

(4)

(5)

(6)

(7)

∆m2 = 7.9+0.6−0.5 × 10−5 eV2

Thank you!