R eactor E xperiment for N eutrino O scillation Liquid Scintillator R&D

1. Reactor Experiment for Neutrino Oscillation Liquid ScintillatorR&D JS Park for RENO Collaboration • Gd have large neutron capture • cross section : ~49000 barn • Gdneeds to transform to • Gd-CBX for loading into • organic phase pH 7.4 pH 5 Compton edge Photo peak MC simulation of internal background pH 6.5 pH 7.2 θ13 Dominant Reference - CsI Crystalwith3cm*3cm*3cm pH 7.5 pH 6.2 pH 9.7 pH 6.0 θ12 Dominant Introduction 20mL Liquid Scintillator • Theta 13 measuring Experiment • Two Identical Detectors : Lower Experimental errors : ~1% level !! • Power Reactors : 6-core • Large Volume Detector : 15 tons • Lower Background : Increase overburden • Detector Configuration • Reaction in the Detector 4-cylindrical detector Inverse Beta Decay Target : Gd-LS Catcher : LS Buffer : Mineral-Oil Veto : Water prompt signal Survival probability with respect to baseline(L) Near Detector Far Detector n ~30us P Gd Total E~8MeV Delayed signal Neutron captured byGadolinium Gd-CBX • Gd to Gd-CBX • Gd-CBX synthesis process • Quality check • We can check whether we truly make Gd-CBX power • with FT-IR Spectroscopy. • No OH group (3200~3500) • No free acid peak (~1700) • We have Carboxylic peak (~1420, ~1580) Reaction equation 1. RCOOH + NH3•H2O ->RCOONH4 + H2O 2. 3RCOONH4(aq) + GdCl3*6H2O -> Gd(RCOO)3 + 3NH4Cl After reaction pH Neutralization pH Gd-CBX precipitated !! Gd-CBX powder was rinsed with 18MΩ waterfor several times and dried in vacuumdesiccator. OH group Free acid peak • Gd-CBX powder for RENO Detector • Loading into LAB and purity • We can load Gd-CBX into LAB by 0.1% (1g/L). • ~ 95% of purity has been achieved. • Final Gd-CBX powder • After grinding, store in a petri dish No Free Acid Carboxylic peak No OH Group Liquid Scintillator • Required Properties • Fluor Optimization • Light Yield Measurement • Radioactive Background • Transparency • High light yield • Long term stability • High radiopurity • Safety matter • Reasonable price • Massive quantity available LY saturated when PPO 3g/L and bis-MSB 30mg/L Using Cs source : 0.662MeV Liquid Scintillator ingredients : Base solvent + primary scintillating fluor + secondary wavelength shifter • Internal background material : 238U, 232Th, 40K • PMT glass is dominant internal background material : ~10Hz • LS radioimpurity contribute to background : ~2Hz (10-12 g/g) PPO After Effect of wavelength shifter ICP-MS result of radioimpurity Before General Elements of Liquid Scintillator PMT sensitive region Bis-MSB Compton edge FT-IR Graph