KamLAND Results Junpei Shirai for the KamLAND Collaboration Tohoku University NOW2006, Conca...

KamLAND ResultsKamLAND Results

Junpei ShiraiJunpei Shiraifor the KamLAND Collaboration for the KamLAND Collaboration

Tohoku UniversityTohoku UniversityNOW2006, Conca Specchiulla, ItalyNOW2006, Conca Specchiulla, Italy

Sep.10-15, 2006Sep.10-15, 2006

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SUN…SUN…EarthEarth

ReactorReactor

KamLAND

KamLAND(Kamioka Liquid scintillator

Anit- Neutrino Detector)

Challenges real time detectChallenges real time detection of ion of Low energy neutrinos !Low energy neutrinos !

1: Reactor experiment2: Geo detection3: Solar detection

Properties of neutrinosProperties of neutrinos 　　 andandNeutrino-generation Neutrino-generation Mechanizms in nature.Mechanizms in nature.

etc.10MeV

K.Nakamaura et al

Supernova

Relic supernova

1MeV

Geo Reactor

Solar

Galactic Atmospheric

Expected neutrino spectra from various sources

KamLAND CollaborationKamLAND Collaboration




A.SuzukiA.Suzuki

Tohoku University, Japan,Tohoku University, Japan,California Institute of Technology, USACalifornia Institute of Technology, USAUniversity Bordeaux 1, France,University Bordeaux 1, France,Drexel University, USA,Drexel University, USA,IHEP, China,IHEP, China,Kansas State University, USA,Kansas State University, USA,Triangle Universities Nuclear Lab., USA,Triangle Universities Nuclear Lab., USA,

University of Alabama, USA,University of Alabama, USA,University of Hawaii, USA,University of Hawaii, USA,University of New Mexico, USA,University of New Mexico, USA,University of Tennessee, USA,University of Tennessee, USA,Lawrence Berkeley National Lab., USA,Lawrence Berkeley National Lab., USA,Louisiana State University, USA,Louisiana State University, USA,Stanford University, USAStanford University, USA

~90 physicists from 14 Institutes

KamLAND Reacotor experimentKamLAND Reacotor experimentKamLAND Reacotor experimentKamLAND Reacotor experiment



Challenging the Solar Neutrino Problem (SNP)

Challenging the Solar Neutrino Problem (SNP)Long History since late 1960's!

Cl, H2O, Ga experiments all showed significantly less flux than the SSM prediction.

Neutrino oscillation naturally explained the results, but several solutions existed in (m2-mixing angle) plane. SNO discovered active non-e component in the flux by using both CC (only e) and NC (total active ’s) reactions. This strongly suggests neutrino oscillation.The LMA (m2~105eV2) solution seems quite promising, but no single experiment uniquely determined the solution.

A decisive experiment is needed using man-made neutrinos.A decisive experiment is needed using man-made neutrinos.Reactor experiments have played a crucial role in this point !Reactor experiments have played a crucial role in this point !

[SNP]

Reactor: powerful tool for studying neutrino oscillationReactor: powerful tool for

studying neutrino oscillation

Pure and high intensity neutrino "beam" is provided.Pure and high intensity neutrino "beam" is provided.

n+235U→X+Y+2n

Fission products: neutron rich → - decays→[~6's]+[~200MeV]/fission

Typical power reactor (3GWth)→ 5.6×1020 /s, ~1/4 is detected by

ee

The energy is low:The energy is low: E　 8.5MeV→<~

The flux and the spectrum of are well understood. The flux and the spectrum of are well understood. ee

[Power reactors] Isotopic components of the fuel elements(235U, 239Pu, 238U, 241Pu) are estimated by the initial ones and the thermal power. The flux and spectrum of each element is studied and the total flux uncertainty is ~2% !

A large L/E factor in sin2 is obtained

m2L 4E

to be sensitive to small m2.

e p→e+n

Long history since the first detection of neutrinos by F.Reines in 1950's.

Reactor experimentsReactor experiments

e

ee

Detector

Disappearance experiment

1-sin22sin2m2L 4E

No oscillation up to a distance No oscillation up to a distance L~ O(1)km (L~ O(1)km (mm22<O(10<O(10-3-3) eV) eV22).).

ee

e p→e+n

Neutrino flux has been well understood.

The technique using a large volume (~10tons) liquid scintillator has been established.

Before KamLAND,

Liquid scintillator

Cross section of has been understood very precisely (0.2%).

e p→e+n

N obs

./N n

o-os

cil

Reactor

(L: flight distance)

KamLAND reactor neutrino experiments

KamLAND reactor neutrino experiments



Kamioka

53 Japanese power reactors.53 Japanese power reactors.26 are concentrated at 26 are concentrated at L=138-214km with 80GWth!L=138-214km with 80GWth!

<L>~180km<L>~180km

KamLAND1000ton LS

With ~100 times larger L/E With ~100 times larger L/E than before KamLAND is senthan before KamLAND is sensitive to sitive to mm2 2 ~10~10-5-5eVeV22 and c and can test the solar LMA soluan test the solar LMA solution!tion!

KamLAND DetectorKamLAND DetectorSite: Kamioka undergroundmine, Gifu prefect., 2700m.w.e.Cosmic muon rate: 0.34Hz

Calibrationdevice

Rn free air

Stainless steel tank (18m)

13m

LS(Normal dodecane(80%)+Pseudo-cumene(20%) +PPO(1.5g/l))

Balloon(135mt; EVOH/3Ny/EVOH)Buffer oil (Normal dodecane+ iso-paraffin: 2.5mt, LS-BO=-0.04%)

1325 17”PMTs+554 20”PMTs(34% of 4, 350p.e./MeV,t~1.9ns (17”PMT))

Pure water (3.2kton)20m 225 20”PMTs

Rock

Outer Detector

Central Detector

KamLAND areaKamLAND area

Control room

Rn-free gas system

Detector

Water purification systemWater purification system

2.2km

1km

To the mine entrance

Oil purification system

Mt.Ikenoyama

Time and space correlation, andTime and space correlation, andDelayed Delayed energy energy → → Significant reduction of backgorunds Significant reduction of backgorunds

detection in KamLANDdetection in KamLANDdetection in KamLANDdetection in KamLAND

ep

e+e

n

p

d

(0.51)

(0.51)

(2.2MeV)

[Prompt e+ signal]

[Delayed by neutron capture]

[E1.8MeV]Eprompt

=Te++ annihilation 's=E0.8MeV

~200s

Te+

+ p e+ + n

e

Results of reactor

PeriodExposure(ton ・ y)

|rp|,|rd|

(m)|rp-rd| (m)

Tp-d (s)Ed (MeV)

Ep (MeV)

Nno-osc.exp

Nobs

Nbkg

Mar.4- Oct.6, '02

162 < 5m1.6 m0.5-6601.8-2.6 > 2.6

86.8±5.6 54 1±1

Mar.9, '02- Jan.11,'04

766 5.5 2

0.5-1000Same

2.6-8.5365±23.7

258 17.8±7.3

1st 2nd

0.611±0.611±0.085±0.0410.085±0.041

0.658±0.658±0.044±0.0470.044±0.047

[99.95%CL] [99.998%CL]

Phys.Rev.Lett. 94, 081801 (2005)

2.6MeV

Disappearance !Disappearance !

Spectral DistortionSpectral DistortionNno-osc.exp

[Nobs-Nbkg]

Oscillatory behaviorOscillatory behavior

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Decay

Decoherence

Oscillation

L0/E distribution (180km)

Δ m2=

7.9+0.6-0.5 ×10-5eV2

tan2θ= 0.4+0.10-0.07

Solar+KamLANDOscillationOscillationparametersparametersare preciselyare preciselyDetermined !Determined !

10-5

10-4

m2

eV2

m2 (e

V)2

tan20.1 1 10

tan25

6

7

8

9

10

411

12×10-5

Prospects of KamLAND reactor expereiment

Prospects of KamLAND reactor expereiment

“4 system”

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

Keep data taking !Keep data taking !Reduce systematic error by a new calibration systemReduce systematic error by a new calibration systemin place of the vertical-axis calibration. in place of the vertical-axis calibration.

Detector (%)Fiducial vol. 4.7Energy threshold 2.3Efficiency of cuts 1.6Live time 0.06

Reactor power 2.1Fuel composition 1.0e spectra 2.5Cross section 0.2

Now ready !

Systematic error : 6.5%

KamALND: challenging GeoneutrinosKamALND: challenging Geoneutrinos



Large heatflow from the EarthLarge heatflow from the Earth

~60mW/m244.2±1.0 TW (Pollack, '93),31±1 TW (Hofmeister, '05)(~10,000 power reactors)

The heat source has not been well understood.The heat source has not been well understood.Volcanoes, earthquakes,Plate tectonics,Plume tectonics,Magnetic field of the Earth

Dynamics of the Earth

Radiogenic heat has been considered to be very important!Radiogenic heat has been considered to be very important!Carbonacious chondrite :Chemical component of the earth [BSE (Bulk Silicate Earth) model]

238U(8TW), 232Th(8TW),40K(3TW)

19TW

Measured points>20,000

Geoneutrinos as a probe of Radiogenic Heat

Geoneutrinos as a probe of Radiogenic Heat

4040KK

.5 1 1.5 2 32.51.8MeV1.8MeV 3.27MeV3.27MeV

214Bi212Bi

KamLAND

€

e p→ e+n

238238UU

234Pa228Ac

208Tl

232232ThTh

238U→206Pb: 6 +51.7MeV232Th→208Pb: 4 +42.7MeV

40K→ 40Ca+e-+ +1.31MeVee

e

[89%]

Direct information of radiogenic heat ! (Eder('66), Marx('69))Direct information of radiogenic heat ! (Eder('66), Marx('69))

KamLAND: Geo- AnalysisData sample: Live-time 749.1±0.5 days (Mar.'02-Nov.'04)

Selection conditions (after the on cut)Low energy (<3.3MeV) Background (external , radio-impurity)

Fiducial vol (|rp|, |rd|) < 5m|rp-rd| < 1m

Tp-d 0.5s- 500sEprompt 0.9-2.6MeV

Ed

Efficiency (68.7±0.7)%

<5.5m< 2m

0.5s- 1000s

same

2.6-8.5MeV

(89.8±1.5)%

[2nd reactor][Geo

1.8-2.6MeV

Energy spectra in KamLAND

(α,n)

Th U

BG-totalEvents/0.17MeV

Data

Geo-νNature 436, 499 (2005)

Accidentals

Antineutrino Energy EAntineutrino Energy E(MeV)(MeV)

Reactor ν

U, Th prediction prediction of the Earth modof the Earth model (16TW)el (16TW)

Reactor

Observed: 152 eventsEstimated BG: 127±13 events 2525 +19+19

-18-18 eventsevents

(80.4±7.2)

(42±11)

(2.38±0.01)

Rate+Shape analysisRate+Shape analysisN

U+

NT

h(ev

enta

)

(NUNTh)/(NU+NTh)

NU+NTh (events)

2 90%CL

4.5 54.2

Th/U mass ratio=3.9

U+Th=21 U+Th=21 (U=3, Th=18)(U=3, Th=18) U+Th=28U+Th=28

Consistent with the rate anConsistent with the rate analysis (alysis (25 25 ) and the E) and the Earth model (arth model (1919) within) within 1 1σ.σ.

The Earth model (Th/U mass ratio=3.9) U+Th=19

The Earth model (Th/U mass ratio=3.9) U+Th=19

U/Th freeU/Th free

+19+19-18-18Radiogenic Power

< 60TW (99%CL)

(,n) Background(,n) Background



222Rn

210Pb 210Bi 210Po

206Pb5.3MeV)Quenched, 21.1Bq/FV

13C→16O(*)+n[1%]

16O*→, e+e- (~6MeV)n+p→n+p n+12C→12C*(4.4)+n

Primary

ReactorGeo

n+p→d+Secondary

n+p→n+p

12C*16O*

Uncetainty: 26%Cross section 20%210Po rate 14%Proton quench 10%

4% (New data)

Measurement with n beam

Events <0.9MeV

(t1/2=22.3y)

Reduce uncertaity of (,n)

Hit the LS with mono-energetic neutrons to measure visible energy of the recoil proton in n+p→n+p.

Neutron detectors(En, n)

LS sample

OKTAVIAN @OSAKA Univ.

Measurement of the proton quenching factor in n+p→n+p.

Measure (,n) events in KamLAND below 0.9MeV; pure (,n) events to know 210Po decay rate. → Continued, Needs statistics.

New cross section data of 13C(,n)16O. Harissopulous et al. (2005), sys. uncertaity 20%→4%.

KamLAND KamLAND 77Be Solar NeutrinoBe Solar Neutrino

DetectionDetection

KamLAND KamLAND 77Be Solar NeutrinoBe Solar Neutrino

DetectionDetection



Towards Towards 77Be solar Be solar Towards Towards 77Be solar Be solar

5MeV5MeV300KeV300KeV

Long lived 210Pb(T1/2=22.3y) and 85Kr(T1/2=10.8y) in the LS must be removed by factors ~105!

SuperKSNO

KamLAND

77Be Be : Second largest flux. : Second largest flux. Theoretical Uncertainty is large (10%).Theoretical Uncertainty is large (10%).No direct measurement so far.No direct measurement so far.

7Be(862KeV)

Detection by KamLAND

ee--→→ee--

Single ionization eventwith Evis<665KeV.

Purification of the 1000 ton LS

Purification of the 1000 ton LS

LS

Purification by Purification by Distillation Distillation ((210210Pb) &Pb) &NN22 purge ( purge (8585Kr)Kr)


LS

Construction of theConstruction of thepurification systempurification systemis finished this month !is finished this month !

Test plant(Tohoku

University)

7Be

Next year !Next year !Next year !Next year !

Lead removal

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(~3×10-5 reduction)

Purification Method

Distillation tower

TanksN2-purge tower

1.5m3/hr

KamLANDarea

Reactor & Geo-after

purification

Reactor & Geo-after

purification





No reactor caseNo reactor case

±35%±35%

Afterpurification

The same data taking periodwith enlarged fiducial volume.

±54%(now)±54%(now)

Total data±28%

<30TW(99%CL)Check theEarth model !

No (,n) & Reduced accidentals

Fiducial volume isenlarged !

Geo

Reactor

(,n) accidental

Fast neutrons

16O*

14C*

6.5m

(R/6.5m)3Fid. Volume

Prom

pt Ene

rgy (M

eV)

5.5m5m

Reactor neutrino

Towards pep/CNO detection

10-6 reduction of 210Pb, 85Kr assumed

After removal of After removal of 210210Pb and Pb and 8585Kr, Kr, 1111C which is generateC which is generated by muons makes a dominant BG in 1~2 MeV region fod by muons makes a dominant BG in 1~2 MeV region for pep/CNO r pep/CNO detection. detection.

11C→11B+e++=29.4m, Q=1.98MeV

pep

RR

tt

Remove 11C by 3-fold coincidence

~95% of 11C production is accompanied by neutrons

1212C+X→C+X→1111C+n+Y+…C+n+Y+…

X=,n,p,,e,

1) Muon2) Neutron (2.2MeV af

ter ~200s)3) 11C decay(=29.4m)

11C-n

+ signal

200cm

select L<50cm,#ndetected>0)

KamLAND 11C detection

Take 3-fold coincidence:

1.4 1.6 1.8 2.01.21.0

Visible energy (MeV)

Pep/CNO : prospects

CNOpep

7Be

3 years data3 years data

1111CC

Improve muon fitter and muon tracking device.

5% of 11C remains.

New electronics to detect neutrons after the large muon signal (design finished).

Issues:

Next slide

Electronics for 11C tagging Design finalized

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ickTi

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B

Main Circuit

AnalogueFront End Circuit





High multiplicity events after the muon (spallation neutrons)with absolutely zero dead-timeand quick recovery

×12 /main board

8B solar

from Pena-Garay

To find upturn toward the low energy by the Matter effect.

232Th concentration in the LS is (5.2±0.8)×10-17 g/g from Bi→Po decay.

208Tl (→, 5MeV) in the LS dominates the signal.

232Th: 212Bi→212Po KamLAND

0.17Bq/m3

Mar-Sep,2002

If Th is removed by purification If Th is removed by purification to ~10to ~10-3-3, then we have a chance !, then we have a chance !

212Po

208Tl

212Bi

208Pb

(36%)

(64%)

KamLAND: SummaryKamLAND: SummaryKamLAND: SummaryKamLAND: Summary

First challenge of Geo-neutrino detection has been made by KamLAND. Further reduction of systematic uncertainty of (,n) background is underway.

Construction of a new purification system is finished this month and we start LS purification right away.

KamLAND has established e oscillation. Under the CPT invariance the SNP has been solved and oscillation parameters have been determined.

KamLAND enters the solar phase next year. High quality data of reactor and geo-neutrinos will also be obtained.

New "4 calibration system" has been ready for significantreduction of systematic errors to get improved measurement of oscillation parameters.

KamLAND Results Junpei Shirai for the KamLAND Collaboration Tohoku University NOW2006, Conca...

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