Presentation on theme: "2007 March 21stLAUNCH MPI, Heiderberg1 Solar Neutrino at KamLAND Sei Yoshida Reserch Center for Neutrino Science, Tohoku Univ. for the KamLAND."— Presentation transcript:
2007 March 21stLAUNCH Workshop @ MPI, Heiderberg1 Solar Neutrino at KamLAND Sei Yoshida Reserch Center for Neutrino Science, Tohoku Univ. for the KamLAND Collaboration
2007 March 21stLAUNCH Workshop @ 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 Workshop @ 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 Workshop @ 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 Workshop @ 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 Workshop @ MPI, Heiderberg7 Required Reduction by Purification 222 Rn 3.8 d < 1mBq/m 3
2007 March 21stLAUNCH Workshop @ MPI, Heiderberg8 R&D Study for Distillation Test Apparatus @ Tohoku Univ. Achievement Impurity Reduction Impurity Reduction 210 Pb ~7×10 -5 40 K > 4×10 -2 85 Kr ~1×10 -6 39 Ar ~1×10 -6 Almost acheived required level
2007 March 21stLAUNCH Workshop @ MPI, Heiderberg9 Expected Spectrum after Purification 210 Pb :7.7×10 -5 40 K :3.8×10 -2 85 Kr :1.0×10 -6 39 Ar :1.0×10 -6 11 C
2007 March 21stLAUNCH Workshop @ MPI, Heiderberg10 New Purification System Construction finished Test operation to tune up parameters
2007 March 21stLAUNCH Workshop @ MPI, Heiderberg11 Concept of New Purification System Distillation System N 2 Purge Towers N 2 Generator
2007 March 21stLAUNCH Workshop @ MPI, Heiderberg12 Distillation System Liquid scintillator(LS) is fed into small buffer tank (2m 3 )from KamLAND. Different boiling point
2007 March 21stLAUNCH Workshop @ 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 Workshop @ 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 Workshop @ 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 Workshop @ 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 Workshop @ 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 Workshop @ 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 ~10 -15 (not measured yet) 222 Rn ~ 5 Bq/m3 (measured at purif. Area)
2007 March 21stLAUNCH Workshop @ 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 Workshop @ 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 Workshop @ MPI, Heiderberg21 Rn Measurement System
2007 March 21stLAUNCH Workshop @ 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 Workshop @ 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 313 -550 nm) Height is measured by differential pressure gauge and is calibrated for different liquid densities.
2007 March 21stLAUNCH Workshop @ 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 Workshop @ 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 Workshop @ 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 2007. We are now negotiating further delay in blasting activity.
2007 March 21stLAUNCH Workshop @ 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.