2007 March 21stLAUNCH MPI, Heiderberg1 Solar Neutrino at KamLAND Sei Yoshida Reserch Center for Neutrino Science, Tohoku Univ. for the KamLAND Collaboration

2007 March 21stLAUNCH MPI, Heiderberg2 KamLAND Experiment Reactor Neutrino Geo-neutrino KamLAND Solar Neutrino Confirmed oscillation of reactor anti-neutrino, firstly detected anti- neutrino from the earth. Next step,  7 Be solar neutrino detection

2007 March 21stLAUNCH MPI, Heiderberg3 KamLAND Detector Kamiokamine overburden : 2700m.w.e. Muon rate : 0.34Hz Muon rate : 0.34Hz 1000 tons of Liquid Scintillator Mineral Oil : Buffer against external BG 1979 PMTs(17” ” 554) Photocathod caverage : 34% Outer water Cherenkov detector for muon veto KamLAND Detector KamLAND Detector 1 kt Liquid Scintillator 1 kt Liquid Scintillator PMTs

2007 March 21stLAUNCH MPI, Heiderberg4 Solar Neutrino Detection Anti-neutrino detection Small Background Neutrino detection High level of Background Delayed coincidence signature Single unspecific signature

2007 March 21stLAUNCH MPI, Heiderberg5 Internal Background of KamLAND At present Single energy spectrum observed in KamLAND 4 m fiducial volume cut to suppress 40 K and 208 Tl external BG What is remeined background in single energy spectrum?

2007 March 21stLAUNCH MPI, Heiderberg6 Internal Background of KamLAND Main sources of background in the range of 7 Be neutrino 210 Pb(  210 Bi  210 Po )  by distillation 85 Kr  by N 2 purging

2007 March 21stLAUNCH MPI, Heiderberg7 Required Reduction by Purification 222 Rn 3.8 d < 1mBq/m 3

2007 March 21stLAUNCH MPI, Heiderberg8 R&D Study for Distillation Test Tohoku Univ. Achievement Impurity Reduction Impurity Reduction 210 Pb ~7× K > 4× Kr ~1× Ar ~1×10 -6 Almost acheived required level

2007 March 21stLAUNCH MPI, Heiderberg9 Expected Spectrum after Purification 210 Pb :7.7× K :3.8× Kr :1.0× Ar :1.0× C

2007 March 21stLAUNCH MPI, Heiderberg10 New Purification System Construction finished Test operation to tune up parameters

2007 March 21stLAUNCH MPI, Heiderberg11 Concept of New Purification System Distillation System N 2 Purge Towers N 2 Generator

2007 March 21stLAUNCH MPI, Heiderberg12 Distillation System Liquid scintillator(LS) is fed into small buffer tank (2m 3 )from KamLAND. Different boiling point

2007 March 21stLAUNCH MPI, Heiderberg13 Distillation System (PC tower) Pseudocumene(PC) is distilled firstly Operating pressure 2kPa. Boiling point ~ 60 ℃ Rest at the bottom of PC tower  Dodecane + PPO  send to next tower

2007 March 21stLAUNCH MPI, Heiderberg14 Distillation System (NP tower) Dodecane(NP) is distilled secondly. Operating pressure ~2kPa. Boiling point ~ 100 ℃ Rest at the bottom of NP tower  Dodecane + PPO(little concentrated)  send to PPO concentrator (~140 ℃ under 2kPa), NP is evaporated back to NP tower.

2007 March 21stLAUNCH MPI, Heiderberg15 Distillation System (PPO tower) PPO is distilled finally. Operating pressure ~0.6 kPa. Boiling point ~ 190 ℃ Rest at the bottom of PPO tower  Exhaust

2007 March 21stLAUNCH MPI, Heiderberg16 Distillation System (Mixture tank) LS is mixed(blended) with distilled PC,NP, and PPO. Temperature senser and Density meter PC and NP mixture is adjusted by pre-small tank. PPO is mixed with PC ~ 10 wt%, then fed into mixture tank.

2007 March 21stLAUNCH MPI, Heiderberg17 Distillation System (Purge towers) Purging by pure N 2 gas Operating pressure ~ 40 kPa N 2 flow rate 30 ~ 35 Nm 3 /h Series of “Gas – Liq. Mixer”, and “Gas-Liq. Separator”

2007 March 21stLAUNCH MPI, Heiderberg18 N 2 Generator Newly developed/constructed N 2 generator Supply air : Rn less air from outside of mine N 2 supply capacity : 40 Nm 3 /h Emergency 5 Nm 3 /h Emergency 5 Nm 3 /hPurity Ar 0.02 ~ 0.03ppm (measured) Kr ~ (not measured yet) 222 Rn ~ 5  Bq/m3 (measured at purif. Area)

2007 March 21stLAUNCH MPI, Heiderberg19 Monitoring Quality Background Reduction Reduction factors for 210 Pb and 40 K will be monitored by KamLAND The data will be continuously taken during purification. Rn concentration in purified LS Delayed coincidence of Bi-Po  miniLAND Electrostatic collection method after trapping Reduction factor of 85 Kr The system is now tuning. Optical property Attenuation length after distillation Light output

2007 March 21stLAUNCH MPI, Heiderberg20 Monitoring Rn Concentration – miniLAND-- miniLAND ; miniture version of KamLAND 0.4m 3 of acrylic container ( 4×4 cells) NaI solution as light guide to shield radiation from PMTs Pb shield of 15 cm in thickness Borated PE of 5 cm in thickness Measuring Rn concentration by Bi-Po delayed coincidence Sensitivity < 1 mBq/m 3 It can also monitor, Light output Attenuation length System is now ready

2007 March 21stLAUNCH MPI, Heiderberg21 Rn Measurement System

2007 March 21stLAUNCH MPI, Heiderberg22 Rn Concentration in N 2 Gas Purification Area KamLAND Piping line between purification area and N 2 generator, ~100m Rn emanation  consistent with designed value ~ 5  Bq/m 3

2007 March 21stLAUNCH MPI, Heiderberg23 Monitoring Attenuation Length Light 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 nm) Height is measured by differential pressure gauge and is calibrated for different liquid densities.

2007 March 21stLAUNCH MPI, Heiderberg24 Results for Purified LS (MO/PC/PPO) We can already make LS by distilled PC/NP/PPO. No significant deterioration for attenuation length Compareing att. length before and after distillation

2007 March 21stLAUNCH MPI, Heiderberg25 Present Status of Purification Pseudocumene and Dodecane are successfully and stably distillated for a period longer than a month. PPO tower operates as expected, however, stable/continuous operation has not been achieved yet. Complete operation of full system will be tested soon, probably within a month. Quality of purified(distilled and purged) scintillator were measured, no detectable impurities/deterioration has been measured/observed.

2007 March 21stLAUNCH MPI, Heiderberg26 Purification Schedule Recirculation test (soon, within a month) Recirculate small amount of LS into KamLAND to test this process without any purification process. After stable PPO tower operation ( probably within one or two months), recirculation distillated LS into KamLAND using the online distillation system To test recirculation process comletely To check the quality of distilled LS further, recirculate ~50m 3 of distilled LS into KamLAND Regular distillation process, but ….. Full volume replacement will require ~ two months. Unfortunately, there is a time constraint because of scheduled blaster in the mine to install new XMASS facility.(very clese to new purification site). Previously, we requested a delay to the end of March We are now negotiating further delay in blasting activity.

2007 March 21stLAUNCH MPI, Heiderberg27 Summary LS purification system was constructed. Part of operation is successfully running. Monitoring system of LS Quality after purification is almost ready. There is a time constraint.