Liquid Scintillator R&D for RENO

1. Liquid Scintillator R&D for RENO Lee, Jaison For RENO Collaboration KPS@Deajeon

2. Contents • Introduction • RENO Detector • Liquid Scintillator Formulation • Gd Loaded LS • Radiopurity • LS Purification and Handling System • Summary KPS@Deajeon

3. Introduction Prerequisites of Liquid Scintillator • Anti-neutrino Target (Gd loaded) - Light Yield ↑ : Good Scintillating Material - Attenuation Length ↑ : Transparency ↑ - Stability ↑ : Compatible with Acryl Vessel - # of free Proton ↑ : H/C ↑ - Systematic error ↓ : Well understanding mono-molecule , Radiopurities ↓ • Gamma Catcher • - Light Yield ↑ : Good Scintillating Material • - Attenuation Length ↑ : Transparency↑ - Stability ↑ : Compatible with Acryl Vessel • - Systematic error ↓ : Radiopurities ↓ KPS@Deajeon

4. Introduction • General Compositions of Liquid Scintillator • Other Experiments • KamLAND : PC(20%)+Dodecane(80%)+PPO • Palo Verde : PC(40%)+M.O.(60%)+PPO+bis-MSB+Gd KPS@Deajeon

5. Introduction • Liquid Scintillator R&D - Determination and optimization of quantity of ingredients (fluor, wavelength shifter) - Measurement of light yield - Measurement of optical properties (attenuation length, transmittance, etc) - Gd loading to liquid scintillator - Long-term stability - Liquid handling and purification system • Co-work with INR/IPCE of Russia KPS@Deajeon

6. RENO Detector ×2 (Near and Far) KPS@Deajeon

7. CnH2n+1-C6H5 (n=10~14) Light Yield PC100% LAB100% PC40% PC20% LAB100% PC20% N2 LAB60% LAB80% MO80% Liquid Scintillator Base Solvent (LAB) - High Light Yield : not likely Mineral oil(MO) - Replace MO and even Pseudocume(PC) probably - Good transparency : ~20m, better than PC - High Flash point : 147oC (PC : 48oC) - Environmentally friendly (PC : toxic) - Components well known, Mineral Oil : not well known - Domestically available: Isu Chemical Ltd. + PPO (Fluor) + bis-MSB (WLS) KPS@Deajeon

8. Optimized PPO Concentration 3 g/L Optimized bis-MSB Concentration 30 mg/L Bis-MSB concentration [mg/l] Liquid Scintillator KPS@Deajeon

9. Gd Loaded LS Gadolinium(metal) cannot be dissolved in the organic solvent!! → Make Gd-salt using ligand KPS@Deajeon

10. precipitation Gd Loaded LS Rinse with 10MΩ water several times KPS@Deajeon

11. Radiopurity • Radioimpurities (40K, 232Th and 238U) in the LS can make the accidental background with neutrons coming from cosmic muons. • Single event rate by radioimpurites is calculated by full detector simulation based on GEANT4, and with 10-12 g/g of concentration of each isotope it will be ~3 Hz. Concentration of LAB (ICP-MS) KPS@Deajeon

12. LS Handling and Purification System KPS@Deajeon

13. Wing tunnel LS 공간 진입터널 Control room LS Handling and Purification System KPS@Deajeon

14. Summary • We are doing LS R&D for RENO. • The composition of LS has been optimized. • Gd is successfully loaded to LS, and its concentration can be measured by titration. • GdR3 will be produced at large scale for Mockup and full detector. • We decided the LS formulation for Mockup detector. • We continue to test the long tem stability of LS. • We are designing the LS purification and handling system. • We are going to adapt the results of R&D to Mockup. KPS@Deajeon

15. Back Up KPS@Deajeon

16. LAB Component with GC-MS CnH2n+1-C6H5 (n=10~14) KPS@Deajeon

17. Light Yield of Liquid Scintillator KPS@Deajeon

18. Performance of Gd in PC & LAB Light output spectra Absorption spectra w/o Gd 100% 82% 96% • LAB has lower optical absorption, better attenuation length • 100% LAB and PC have similar light outputs • We got similar results with BNL & Daya Bay experiment KPS@Deajeon

19. Gd 적정 방법 적정용 뷰렛 Buffer solution EDTA 지시약 적정 전의 색 끝났을 때의 색 + 필요한 물품 : 비커, 증류수, GdLS, indicator, buffer solution, EDTA, 적정용 뷰렛 Indicator (Xylenol Orange): 보라색-> 노란색으로 변함 Buffer solution: 수소이온 농도를 일정하게 유지하려고 하는 용액 EDTA (EthyleneDiamineTetraAcetic acid): Gd와 높은 반응성 1. 비커에 증류수를 20ml 가량 넣는다. 2. GdLS를 2ml 넣는다. 3. Buffer solution 2ml + indicator 4 drop : 비커에 담긴 용액이 엷은 보라색을 띈다. 4. 용액의 색이 노란색으로 변할 때까지 EDTA 추가 VEDTA * CEDTA = VGdLS * CGdLS KPS@Deajeon