kamland double beta decay experiment using 136 xe

Masayuki KogaMasayuki Koga ICHEP2010ICHEP2010 11

KamLAND double beta decay KamLAND double beta decay experiment using experiment using 136136XeXe

( KamLAND-Zen )( KamLAND-Zen )

Masayuki Koga @ RCNS Tohoku University

Contents: Contents: summary of KamLANDsummary of KamLAND KamLAND-Zen experimentKamLAND-Zen experiment


１０００ｍ１０００ｍ


1998-2001: construction1998-2001: construction 2002: data-taking start2002: data-taking start We got some resultsWe got some results ・　・　 reactor anti-neutrino observationreactor anti-neutrino observation neutrino deficit at ~175km base neutrino deficit at ~175km base spectral distortionspectral distortion precise oscillation parameters measurementprecise oscillation parameters measurement

・　・　 Geo neutrino detectionGeo neutrino detection 2009~: KamLAND is running for 2009~: KamLAND is running for 77Be solar neutrino observation after Be solar neutrino observation after

the LS distillation the LS distillation 2011~: Xe phase2011~: Xe phase

Summary of KamLAND Summary of KamLAND


Reactor Anti-NeutrinoReactor Anti-Neutrino

LMA2LMA2


Geo Neutrino observationGeo Neutrino observationRadio active nuclei produce heatRadio active nuclei produce heat

238238U -> U -> 206206Pb + 8Pb + 844He + 6eHe + 6e-- + 6ν + 6νee+ + 51.7MeV51.7MeV 232232Th -> Th -> 208208Pb + 6Pb + 644He + 4eHe + 4e-- + 4ν + 4νee + + 42.7MeV42.7MeV 4040K -> K -> 4040Ca + eCa + e-- + ν + νee + + 1.31MeV1.31MeV

Terrestrial heat flow 31~44TWTerrestrial heat flow 31~44TW

Contribution of radioactive nuclei Contribution of radioactive nuclei ~20TW~20TW

( U series 8TW / Th series 8TW / ( U series 8TW / Th series 8TW / 4040K 4TW )K 4TW )

from Crust + Mantle from Crust + Mantle

-- based on Chondrite model (BSE model)-- based on Chondrite model (BSE model)

Upper crust of landUpper crust of land

U:2. 8ppm / Th: 10.7ppm U:2. 8ppm / Th: 10.7ppm

Rudnick et al (1995)Rudnick et al (1995)

No radiogenic heat from the coreNo radiogenic heat from the core

Th/U ratio ~3.7Th/U ratio ~3.7


Geo Neutrino observationGeo Neutrino observation preliminarypreliminary result (K.Inoue, Neutrino2010)result (K.Inoue, Neutrino2010)

2.8n fast atm.

0.12.0 9Li

0.177.4 accidental

2.18165.3 On),C(

5.267.484 reactor

32.3729.4 BG total

1613

e

2.6MeV-0.9in candidates 841

yearsprotontarget32103.49 :exposure total

2009 4,November ~ 2002 9,March :set data

test)hypothesisonly -(rate

99.55%exclusion signal Null

events 111 analysisonly -rate 4543-

Rate-Shape-time analysisRate-Shape-time analysis

0 signal is rejected at 0 signal is rejected at 99.997%CL.(>4σ)99.997%CL.(>4σ)

　　　　　　　　　　　　　　　　　　　　　　　　 (rate-shape-time Δχ(rate-shape-time Δχ ２２））

# of geo-ν events# of geo-ν events

corresponds to 16TW (for U+Th)corresponds to 16TW (for U+Th)

Consistent with the model predictionConsistent with the model prediction


TNU 3.38

/sec /cm103.43.10

9.9

262.11.1

2928-106


77Be neutrino observationBe neutrino observationLS was purified by the distillation systemLS was purified by the distillation system

(2007 and 2008)(2007 and 2008)

Installed new electronics – for Installed new electronics – for 1313C(α,n) background reduction (on going)C(α,n) background reduction (on going)

Data-taking continue (to March 2011) Data-taking continue (to March 2011)

KamLAND Zen experimentKamLAND Zen experiment(KamLAND zero neutrino Double Beta decay)(KamLAND zero neutrino Double Beta decay)

RCNS Tohoku UniversityRCNS Tohoku University K. Inoue J.Shirai T.Mitsui M.Koga K. Nakamura Y.Kishimoto S.Yoshida Y.Gando H.Ikeda K. Inoue J.Shirai T.Mitsui M.Koga K. Nakamura Y.Kishimoto S.Yoshida Y.Gando H.Ikeda

I.Shimizu Y.Minekawa Y.Takemoto A.Terashima H.Watanabe H.Takahashi T.Morikawa I.Shimizu Y.Minekawa Y.Takemoto A.Terashima H.Watanabe H.Takahashi T.Morikawa H.Yabumoto H.Yoshida N.Takahashi B.Xu E.Chatwin-Davies Y.Ohno R.Kato T.NakataH.Yabumoto H.Yoshida N.Takahashi B.Xu E.Chatwin-Davies Y.Ohno R.Kato T.Nakata

KEKKEKA.SuzukiA.Suzuki

IPMU Tokyo UniversistyIPMU Tokyo UniversistyA.KozlovA.Kozlov

University of TennesseeUniversity of TennesseeY.EfremenkoY.Efremenko

Colorado State universityColorado State universityB.E,Berger, D.WarnerB.E,Berger, D.Warner

TUNLTUNLW.Tornow, D.Markoff, H.KarwowskiW.Tornow, D.Markoff, H.Karwowski


禅禅


Advantage for ββAdvantage for ββ experiment on experiment on KamLAND KamLAND

KamLAND hasKamLAND has

huge volume: 1,200mhuge volume: 1,200m33 Liquid Scintillator Liquid Scintillator

Ultra low radioactivityUltra low radioactivity

Low threshold : ( It will be ELow threshold : ( It will be Ethth= few 100keV)= few 100keV)

established distillation techniqueestablished distillation technique

experience of balloon developmentexperience of balloon development

new electronics (from 2009)new electronics (from 2009)

mach advantage for 0νββmach advantage for 0νββ experiment !experiment ! Disadvantage Disadvantage

Current Energy Resolution: Current Energy Resolution:

(34% photo coverage)(34% photo coverage)

This is enough on earlier stage !This is enough on earlier stage !

)(MeVE


Merit of using Merit of using 136136Xe on KamLANDXe on KamLAND

Rodin et al., Nucl. Phys. A793 (2007)213-215

Available the Isotopic enrichment (>90%)Available the Isotopic enrichment (>90%) purification method was establishedpurification method was established solubility to LS > 3%, easy extractedsolubility to LS > 3%, easy extracted slow 2νββ (T2ν

1/2 >1022 years)

small T0ν/ T2ν ratio

* basic idea by R.S.Raghavan

Phys. Rev.Lett.72 (1994)

KamLAND-Zen projectKamLAND-Zen project

Nucleas T0ν1/2(50 meV) T2ν

1/2 measured

(year)

Nat.Abundane

（％）Q-value

（ keV ）136Xe→136Ba 4.55×1026 >1022 8.9 2476


KamLAND-Zen projectKamLAND-Zen project

3.4mφ balloon3.4mφ balloon

4.6mφbaloon4.6mφbaloon

Brighter LSBrighter LS

WinstoneWinstonecorn mirrorcorn mirror

1st phase enriched Xe 400kg　 R=1.7m balloon　 V=20.5m3,S=36.3m2

LS : C10H22(81.8%)+PC(18%)　　　 +PPO+Xe(~2.5wt%) ρLS ：　 0.78kg ／ℓ high sensitivity with low cost

tank opening (2013 or 2015)

2nd phase enriched Xe 1000kg R=2.3m balloon　 V=51.3m3,S=66.7m2

improvement of energy resolution (brighter LS, higher light concentrator )

Developments of system for 400kg Xe phaseDevelopments of system for 400kg Xe phase


1. Xe gas loading/ extraction system1. Xe gas loading/ extraction system

2. New electronics - MOGURA2. New electronics - MOGURA

System will be ready in System will be ready in December 2010December 2010

For BG reduction using tagging. For BG reduction using tagging. Installed in 2009.Installed in 2009.

Handling and pressurized test by Handling and pressurized test by water (80μm film, June 2010)water (80μm film, June 2010)

More R&DMore R&D• ultra low contamination filmsultra low contamination films U/Th/U/Th/4040K ~ K ~ 1010-13-13g/gg/g• more thin film ~25μmmore thin film ~25μm

MIB will be delivered to March 2011 MIB will be delivered to March 2011

4. Mini Balloon Φ3.4m4. Mini Balloon Φ3.4m

3. Enriched Xe3. Enriched Xe

• We have 190kg 90% We have 190kg 90% enriched Xe gasenriched Xe gas• Purchase 210kg more toPurchase 210kg more to March 2011 (400kg total)March 2011 (400kg total)


Background study using KamLAND MC (GEANT4) Background study using KamLAND MC (GEANT4) Major BGMajor BG

(1). (1). 136Xe 2νββ

(2). spallation isotopes : 10C, 11Be => 1/10 using new electronics help

(3). 8B solar neutrinos <4.9 events/d/kton on KamLAND

(4). from Mini Balloon (MIB) material : 208Tl, 214Bi => vertex cut,

Simulated Energy Spectrum at KamLANDSimulated Energy Spectrum at KamLAND Assumed Assumed - 400kg 90% enriched Xe loaded LS- 400kg 90% enriched Xe loaded LS- MIB contamination (238U, 232Th, 40K) MIB contamination (238U, 232Th, 40K) = (10-12, 10-12, 10-11)[g/g]= (10-12, 10-12, 10-11)[g/g]- neutrino effective mass <mν> neutrino effective mass <mν> = 150meV (the lower limit of the= 150meV (the lower limit of the current claimed detection)current claimed detection)- TT1/21/2(2νββ) > 10(2νββ) > 102222yy- TT1/21/2(0νββ) > 1.14x10(0νββ) > 1.14x102424y y

- - 1010C 90% tag, C 90% tag, 214214Bi 66% tagBi 66% tag

Summary of BG and signal in signal Summary of BG and signal in signal regionregion

[events/year][events/year]


2200

01/2

T observable

mMG

Target sensitivity of the Target sensitivity of the 400kg phase is 400kg phase is ~60meV~60meV

2 years on 100% fiducial vol. @90% enrichment2 years on 100% fiducial vol. @90% enrichment


summarysummary

KamLAND is running for reactor, Geo, 7Be solar (to 2011)KamLAND is running for reactor, Geo, 7Be solar (to 2011) KamLAND have ability to do 0νββKamLAND have ability to do 0νββ experimentexperiment KamLAND-Zen project will start useing 400kg 90% enriched Xe KamLAND-Zen project will start useing 400kg 90% enriched Xe

from May 2011from May 2011 Target sensitivity on 400kg Phase ~60meV @2yearsTarget sensitivity on 400kg Phase ~60meV @2years Planning Xe1000 phase (from 2013 or 2015: depend on funding)Planning Xe1000 phase (from 2013 or 2015: depend on funding)

Thank you!Thank you!

kamland double beta decay experiment using 136 xe

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