Solar Neutrino at KamLAND

2007 March 21st LAUNCH Workshop @ MPI, Heiderberg 1

Solar Neutrino at KamLANDSolar Neutrino at KamLAND

Sei YoshidaSei YoshidaReserch Center for Neutrino Science, Tohoku Univ.Reserch Center for Neutrino Science, Tohoku Univ.

for the KamLAND Collaborationfor the KamLAND Collaboration

2007 March 21stLAUNCH Workshop @ MPI, Heiderberg 2

KamLAND ExperimentKamLAND Experiment

Reactor NeutrinoReactor Neutrino

Geo-neutrinoGeo-neutrino KamLANDKamLAND

Solar NeutrinoSolar Neutrino

Confirmed oscillation of reactor anti-neutrino, firstly detected anti-Confirmed oscillation of reactor anti-neutrino, firstly detected anti-neutrino from the earth.neutrino from the earth.

Next step, Next step, 77Be solar neutrino detectionBe solar neutrino detection


KamLAND DetectorKamLAND Detector

Kamiokamine overburden : 2700m.w.e.Kamiokamine overburden : 2700m.w.e.

Muon rate : 0.34HzMuon rate : 0.34Hz

1000 tons of Liquid Scintillator1000 tons of Liquid Scintillator

Mineral Oil : Buffer against external BGMineral Oil : Buffer against external BG

1979 PMTs(17” 1325 + 20” 554)1979 PMTs(17” 1325 + 20” 554)

Photocathod caverage : 34%Photocathod caverage : 34%

Outer water Cherenkov detector for muon Outer water Cherenkov detector for muon vetoveto

KamLAND KamLAND DetectorDetector 　　

1 kt Liquid Scintillator1 kt Liquid Scintillator　　

PMTsPMTs


Solar Neutrino DetectionSolar Neutrino Detection

Anti-neutrino detectionAnti-neutrino detection

Small BackgroundSmall Background

Neutrino detectionNeutrino detection

High level of BackgroundHigh level of Background

Delayed coincidence signatureDelayed coincidence signature Single unspecific signatureSingle unspecific signature


Internal Background of KamLANDInternal Background of KamLAND

At present

Single energy spectrum observed in KamLAND Single energy spectrum observed in KamLAND

4 m fiducial volume cut to suppress 4 m fiducial volume cut to suppress 4040K and K and 208208Tl external BGTl external BG

What is remeined background in single energy spectrum? What is remeined background in single energy spectrum?


Internal Background of KamLANDInternal Background of KamLAND

Main sources of background in the range of Main sources of background in the range of 77Be neutrinoBe neutrino210210Pb(Pb( 210210Bi Bi 210210Po ) Po ) by distillation by distillation8585Kr Kr by N by N22 purging purging


Required Reduction by PurificationRequired Reduction by Purification

222222Rn 3.8 d < 1mBq/mRn 3.8 d < 1mBq/m33


R&D Study for DistillationR&D Study for Distillation

Test Apparatus @ Tohoku Univ.Test Apparatus @ Tohoku Univ.AchievementAchievement

Impurity ReductionImpurity Reduction210210Pb ~7×10Pb ~7×10-5-5

4040K > 4×10K > 4×10-2-2

8585Kr ~1×10Kr ~1×10-6-6

3939Ar ~1×10Ar ~1×10-6-6

Almost acheived required levelAlmost acheived required level


Expected Spectrum after Expected Spectrum after PurificationPurification

210Pb :7.7×10-5 40K :3.8×10-2 85Kr :1.0×10-6

39Ar :1.0×10-6

11C


New Purification SystemNew Purification System

Construction finishedConstruction finished

Test operation to tune up parametersTest operation to tune up parameters


Concept of New Purification Concept of New Purification SystemSystem

Distillation SystemDistillation System NN22 Purge Towers Purge Towers

NN22 Generator Generator


Distillation SystemDistillation System

Liquid scintillator(LS) is fed into small buffer tank (2mLiquid scintillator(LS) is fed into small buffer tank (2m33)from )from KamLAND.KamLAND.

Different boiling pointDifferent boiling point


Distillation System (PC tower)Distillation System (PC tower)

Pseudocumene(PC) is distilled firstlyPseudocumene(PC) is distilled firstlyOperating pressure 2kPa.Operating pressure 2kPa.

Boiling point ~ 60Boiling point ~ 60℃ ℃

Rest at the bottom of PC tower Rest at the bottom of PC tower Dodecane + PPO Dodecane + PPO send to next towersend to next tower


Distillation System (NP tower)Distillation System (NP tower)

Dodecane(NP) is distilled secondly.Dodecane(NP) is distilled secondly.Operating pressure ~2kPa.Operating pressure ~2kPa.Boiling point ~ 100Boiling point ~ 100℃ ℃

Rest at the bottom of NP tower Rest at the bottom of NP tower Dodecane + PPO(little concentrated) Dodecane + PPO(little concentrated) send to PPO concentrator (~140send to PPO concentrator (~140℃ ℃ under 2kPa), NP is evaporated back to NP under 2kPa), NP is evaporated back to NP tower.tower.


Distillation System (PPO tower)Distillation System (PPO tower)

PPO is distilled finally.PPO is distilled finally.Operating pressure ~0.6 kPa.Operating pressure ~0.6 kPa.

Boiling point ~ 190Boiling point ~ 190℃ ℃

Rest at the bottom of PPO tower Rest at the bottom of PPO tower Exhaust Exhaust


Distillation System (Mixture tank)Distillation System (Mixture tank)

LS is mixed(blended) withLS is mixed(blended) with distilled PC,NP, and PPO. distilled PC,NP, and PPO.

Temperature senser and Density meterTemperature senser and Density meterPC and NP mixture is adjusted by pre-small tank.PC and NP mixture is adjusted by pre-small tank.

PPO is mixed with PC ~ 10 wt%, then fed into mixture tank.PPO is mixed with PC ~ 10 wt%, then fed into mixture tank.


Distillation System (Purge towers)Distillation System (Purge towers)

Purging by pure NPurging by pure N22 gas gas

Operating pressure ~ 40 kPa Operating pressure ~ 40 kPa

NN22 flow rate 30 ~ 35 Nm flow rate 30 ~ 35 Nm33/h/h

Series of “Gas – Liq. Mixer”, and “Gas-Liq. Separator”Series of “Gas – Liq. Mixer”, and “Gas-Liq. Separator”


NN22 Generator Generator

Newly developed/constructed NNewly developed/constructed N22 generator generatorSupply air : Rn less air from outside of mineSupply air : Rn less air from outside of mine

NN22 supply capacity : 40 Nm supply capacity : 40 Nm33/h/h

Emergency 5 NmEmergency 5 Nm33/h/h

PurityPurityAr 0.02 ~ 0.03ppm (measured)Ar 0.02 ~ 0.03ppm (measured)Kr ~10Kr ~10-15 -15 (not measured yet)(not measured yet)222222Rn ~ 5Rn ~ 5Bq/m3 (measured at purif. Area)Bq/m3 (measured at purif. Area)


Monitoring QualityMonitoring Quality

Background ReductionBackground Reduction

Reduction factors for Reduction factors for 210210Pb and Pb and 4040K will be monitored by KamLANDK will be monitored by KamLANDThe data will be continuously taken during purification.The data will be continuously taken during purification.

Rn concentration in purified LSRn concentration in purified LSDelayed coincidence of Bi-Po Delayed coincidence of Bi-Po miniLAND miniLAND

Electrostatic collection method after trappingElectrostatic collection method after trapping

Reduction factor of Reduction factor of 8585KrKrThe system is now tuning.The system is now tuning.

Optical propertyOptical property

Attenuation length after distillationAttenuation length after distillation

Light outputLight output


Monitoring Rn Concentration –Monitoring Rn Concentration –miniLAND--miniLAND--

miniLAND ; miniture version of KamLANDminiLAND ; miniture version of KamLAND0.4m0.4m33 of acrylic container ( 4×4 cells) of acrylic container ( 4×4 cells)

NaI solution as light guide to shield radiation from PMTsNaI solution as light guide to shield radiation from PMTs

Pb shield of 15 cm in thicknessPb shield of 15 cm in thickness

Borated PE of 5 cm in thicknessBorated PE of 5 cm in thickness

Measuring Rn concentration by Bi-Po delayed coincidenceMeasuring Rn concentration by Bi-Po delayed coincidenceSensitivity < 1 mBq/mSensitivity < 1 mBq/m33

It can also monitor,It can also monitor,Light outputLight output

Attenuation lengthAttenuation length

System is now readySystem is now ready


Rn Measurement SystemRn Measurement System


Rn Concentration in NRn Concentration in N22 Gas Gas

Purification AreaPurification AreaKamLANDKamLAND

Piping line between purification area and NPiping line between purification area and N22 generator, ~100m generator, ~100m

Rn emanation Rn emanation consistent with designed value ~ 5 consistent with designed value ~ 5Bq/mBq/m33


Monitoring Attenuation LengthMonitoring Attenuation LengthLight beam is collimated onto different wavelength filters.

For each of 21 different liquid heights along the 1 m long Stainless Steel tube (which is coated to minimize scattering) we take the following measurements:

PMT Dark current, measured by using a plug in the filter wheel

Beam intensity using photo-diode

PMT current for each wavelength filter (10 filters from 313 -550 nm)

Height is measured by differential pressure gauge and is calibrated for different liquid densities.


Results for Purified LS (MO/PC/PPO)Results for Purified LS (MO/PC/PPO)

We can already make LS by distilled PC/NP/PPO.We can already make LS by distilled PC/NP/PPO.

No significant deterioration for attenuation length No significant deterioration for attenuation length Compareing att. length Compareing att. length beforebefore and and afterafter distillation distillation


Present Status of PurificationPresent Status of Purification

Pseudocumene and Dodecane are successfully and stably distillated for a Pseudocumene and Dodecane are successfully and stably distillated for a period longer than a month.period longer than a month.

PPO tower operates as expected, however, stable/continuous operation PPO tower operates as expected, however, stable/continuous operation has not been achieved yet.has not been achieved yet.

Complete operation of full system will be tested soon, probably within a Complete operation of full system will be tested soon, probably within a month.month.

Quality of purified(distilled and purged) scintillator were measured, no Quality of purified(distilled and purged) scintillator were measured, no detectable impurities/deterioration has been measured/observed.detectable impurities/deterioration has been measured/observed.


Purification SchedulePurification Schedule

Recirculation test (soon, within a month)Recirculation test (soon, within a month)Recirculate small amount of LS into KamLAND to test this process without any Recirculate small amount of LS into KamLAND to test this process without any purification process.purification process.

After stable PPO tower operation ( probably within one or two months), After stable PPO tower operation ( probably within one or two months), recirculation distillated LS into KamLAND using the online distillation recirculation distillated LS into KamLAND using the online distillation systemsystem

To test recirculation process comletelyTo test recirculation process comletely

To check the quality of distilled LS further, recirculate ~50mTo check the quality of distilled LS further, recirculate ~50m33 of distilled LS into of distilled LS into KamLANDKamLAND

Regular distillation process, but …..Regular distillation process, but …..Full volume replacement will require ~ two months.Full volume replacement will require ~ two months.

Unfortunately, there is a time constraint because of scheduled blaster in the mine Unfortunately, there is a time constraint because of scheduled blaster in the mine to install new XMASS facility.(very clese to new purification site).to install new XMASS facility.(very clese to new purification site).

Previously, we requested a delay to the end of March 2007.Previously, we requested a delay to the end of March 2007.

We are now negotiating further delay in blasting activity.We are now negotiating further delay in blasting activity.


SummarySummary

LS purification system was constructed.LS purification system was constructed.

Part of operation is successfully running.Part of operation is successfully running.

Monitoring system of LS Quality after purification is almost ready.Monitoring system of LS Quality after purification is almost ready.

There is a time constraint.There is a time constraint.

Solar Neutrino at KamLAND

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