RENO Liquid Scintillator R&D Daejung Kong (KNU) KPS Spring Meeting, April 19, 07 경북대, 경상대, 동신대, 부산대, 세종대, 서울대, 서울시립대, 성균관대, 전남대, INR/IPCE ( 러시아 ) Introduction Gd-LS R&D Purification Summary and plan

Target - LSc + Gd Gamma catcher - LSc Buffer - Non Scinti. Veto - Water Shielding p ν e e + e - γ (0.511MeV) n Gd γ γ γ γ E g å ~ 8MeV 30μs prompt signal Delayed signal Core component Liquid Scintialltor for RENO Gadolinium Large neutron X-section, BKG rejection (coincidence) Liquid Scintillator High light output, good optical properties, Long term stability, H/C, Radiopurity

2007 KPS spring Meeting3 Gd+Liquid Scintillator R&D  Liquid Scintillator R&D 에서 수행하는 사항들 : - 구성물질의 조합과 배합 비율 결정 - 빛 방출량 측정 - 투광도 및 흡광도 측정 - purification system - 주기적 측정에 의한 장기적 안정성 검사 - 변색 여부 검사 - 아크릴의 거부 반응 여부  Liquid Scintillator 의 일반적 구성 물질 : AromaticOilFluorWLSGd-compound PC(Pseudocumene), PXE, LAB Mineral oil, Dodecane, Tetradecane, LAB PPO, BPO Bis-MSB, POPOP 0.1% Gd compounds with CBX or BDK

2007 KPS spring Meeting4 ChoozPalo Verde GdGd(NO 3 ) 3 Gd 2 O 3 Loading Methods Dissolved in hexanol + LSConverted to carboxylate + LS Light degradation 0.4 % / day0.03 % / day RemarksUnstable  Turned YellowStable  still usable Lesson and R&D about Gd-LS Gd loading is a key issue Gd loading is not trivial Experienced Russian Group (INR) joined  6 months stable Gd-LS R&D with INR

2007 KPS spring Meeting5 Gd compound structure R1R1 3+ Gd R2R2 O O O O O O HC - C-C- H C-C- H R1R1 R1R1 R2R2 R2R2 Gd 3+ R O O O O O O C C C R R CC O - H + O R H H R C CH 2 R 2 C OO GdCBX GdBDK  -diketonates: Carboxylic acids:

2007 KPS spring Meeting6 Liquid Scintillator R&D 현황 R&D Safety 와 환경문제 Domestic Availability Remarks LAB100 RENO/Daya bay Much less toxic YESInexpensive, 환경 친화적 PC20Dod80 Daya Bay/RENOtoxicNOExpensive PXE20Dod80 Double ChoozLess toxicNOUnstable  claimed by Daya bay PC20MO80 PC40MO60 Palo Verde Chooz toxicAvailableComponents?, purification

2007 KPS spring Meeting7 Optimization of Fluor and WLS Optical properties (absorption,..) Measurement of Gd concentration purification (transparency, radio-purity) Measurement of LS components Light output - Nitrogen flushing effect RENO Gd (un)loaded LS R&D 현황

2007 KPS spring Meeting8 Solvent : LAB 1g PPO 2g PPO 3g PPO 4g PPO 5g PPO 6g PPO 7g PPO 10g PPO 20g PPO Optimization of PPO, bis-MSB Concentration  Purified LAB(100) + varying PPO  PPO 3g/l 일 때, LY saturation 0mg/l 10mg/l 20mg/l 30mg/l 40mg/l 50mg/l 60mg/l 100mgl 200mg/l  LAB100+PPO3g/l+bis-MSB30mg/l

2007 KPS spring Meeting9  Beer-(Lamvert-Bouguer) law  = (L/(A 420 -A min )) L: cell path length A: absorption at 420nm 정제 전 정제 후 정제방법 (Al 2 O 3 adsorption) LAB( 이수화학 ) 흡광도 [Abs] 조사

2007 KPS spring Meeting10  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 100% 82% 96% Absorption spectra Light output spectra Performance of Gd in PC & LAB Gd loaded Gd unloaded

2007 KPS spring Meeting11 Sample Composition (ligand) [Gd](%) Remarks 첨가물 1 *3HR0.109HR(0.92m) 2 *3TBP0.108TBP(0.5m) 3 *2TOPO0.118TOPO(99%) 4 *3TOPO0.110TOPO(99%) 측정 결과 indicator buffer solution EDTA ① PH> 5 에서 Gd 은 EDTA 와 반응도 높다 ② EDTA 는 indicator 와 반응해, 보라색에서 노란색으로 색깔 변화 ③ V EDTA * C EDTA = V sample * C sample Indicator GdLS Buffer solution (PH>5) Gd buffer solution (PH>5) Gd 농도 측정 방법

2007 KPS spring Meeting12 적정횟수 Gd Concentration (%) 측정 Attenuation length (m) Note  LS 관련 약품을 살 때는 모두 고순도를 구입해서 사용해야 ( 특히, PPO, ligand)  If not, additional purification will be needed Abs 최종 샘플 흡광도 [Abs], att, 농도 조사

2007 KPS spring Meeting13 정제 전 (m) 정제 후 (m) PXE Dodecane PC MO9.7N/A LAB (batch1) LAB (batch2) Attenuation Length of different solvents before/after purification

2007 KPS spring Meeting14 Transmittance of two different batch samples of LAB B1B2 정제 전후 차이 없음 정제 후가 better 정제 전 B1 > B2 투광도 : batch 에 따라 다소 차이 정제 후 B1 = B2 투광도 batch 에 무관

2007 KPS spring Meeting15 Optimal ratio of LAB and Alumina for purification - Optimization Find optimal ratio of LAB and Al 2 O 3 Using column adsorption method, take purified LAB for each time, naming as batch1, batch2,…  total 10 batches. Measure the absorption spectrums and calculate the attenuation lengths (at 420 nm) of each batch  1:5 (alumina : LAB)

2007 KPS spring Meeting16 Radiopurity level  g/g (Th, U, K) : Daya Bay/Double Chooz S/N > 100 (DB, DC) RENO rediopurity level 측정 : ICP-MS( 기초과학지원연구소 ) 정제 방법 개선 후 정밀도가 높은 장비로 측정 예정 Radiopurity level in LS K [g/g]Th [g/g]U [g/g] Mineral Oil0.77x10-6< 2x10-9< 5x10-10 From Daya Bay TDR

2007 KPS spring Meeting17 Radiopurity level  g/g (Th, U, K) : Daya Bay/Double Chooz S/N > 100 (DB, DC) RENO rediopurity level 측정 : ICP-MS( 기초과학지원연구소 ) 정제 방법 개선 후 정밀도가 높은 장비로 측정 예정 Radiopurity level in LS K [g/g]Th [g/g]U [g/g] Mineral Oil0.77x10-6< 2x10-9< 5x10-10 From Daya Bay TDR

2007 KPS spring Meeting18 Gas Chromatography (GC) with Mass Spectrometry (MS) Measurement of LAB Component using GC-MS Motivation : calculation of # of proton, H/C LAB : (C 6 H 5 )C N H 2N+1 Gas Chromatography Mass Spectrometry (MS)

2007 KPS spring Meeting19 Measurement of LAB components LAB : (C 6 H 5 )C N H 2N+1

2007 KPS spring Meeting20 C 16 H 26 C 17 H 28 C 18 H 30 C 19 H % 27.63% 34.97% 30.23% LAB components with GC-MS LAB : (C 6 H 5 )C N H 2N+1 # of H [m -3 ] = x H/C = 1.66

2007 KPS spring Meeting21 KF-50 KF-70 Measurement of Mineral Oil components Difficult to figure out Component of M.O * KF-50,KF-70 : 서진화학 M.O

2007 KPS spring Meeting22 w/o N 2 flushing w/ N 2 flushing Effect of Nitrogen flushing & purification Light Yield

2007 KPS spring Meeting23 100% 82% 96% N 2 flushing is crucial Effect of Nitrogen flushing & purification Light Yield

2007 KPS spring Meeting24 Summary and Plan  Current Gd (un)load LS R&D Status Investigation of Solvents, Fluors LS mixing procedure developed Purification method developed Start Gd loading into LS with Russian Group  Long term R&D Plan Investigation of radiopurity Developing mass production techniques (purification, filling, etc.,) Long term stability R&D (Light Yield, optical properties) Stability is the most important !!!