1. Soo-Bong Kim Seoul National Univ. Current Status of RENO (Symposium on “Physics of Massive Neutrinos” May 20-22, 2008, Milos, Greece)

2. New Reactor Neutrino  13 Experiment  Lower background - Improved detector design - Increased overburden  CHOOZ : R osc = 1.01 ± 2.8% (stat) ± 2.7% (syst)  Larger statistics - More powerful reactors (multi-core) - Larger detection volume - Longer exposure  Smaller experimental errors - Identical multi detectors → Obtain ~1% precision !!!

3. Detection of Reactor Neutrinos data from CHOOZ hep-ex/0301017v1 (1) 0.7<E prompot <9MeV (2) 5<E delayed <11MeV (3) 1μs<ΔT <200μs e + energy n capture energy

4. RENO Collaboration  Chonnam National University  Dongshin University  Gyeongsang National University  Kyungpook National University  Pusan National University  Sejong University  Seoul National University  Sungkyunkwan University  Institute of Nuclear Research RAS (Russia)  Institute of Physical Chemistry and Electrochemistry RAS (Russia) +++ http://neutrino.snu.ac.kr/RENO

6. Schematic Setup of RENO at YeongGwang

7. Google Satellite View of YeongGwang Site

8. Schematic View of Underground Facility 100m300m 70m high 200m high 1,380m290m Far Detector Near Detector Reactors

9. Schedule Activities Detector Design & Specification Geological Survey & Tunnel Design Detector Construction Excavation & Underground Facility Construction Detector Commissioning 200620072008 2009 369 12 369 369 369

10. Comparison of Reactor Neutrino Experiments ExperimentsLocation Thermal Power (GW) Distances Near/Far (m) Depth Near/Far (mwe) Target Mass (tons) Double-CHOOZFrance8.7280/105060/30010/10 RENOKorea17.3290/1380120/45016/16 Daya BayChina11.6360(500)/1985(1613)260/910 40  2/80

11. Summary of Construction Status 03~10, 2007 : Geological survey and tunnel design are completed. 05~12, 2008 : Tunnel construction Hamamatsu 10” PMTs are considered to be purchased. (expect to be delivered from March 2009) SK new electronics are adopted and ordered. (will be ready in Sep. 2008) Steel/acrylic containers and mechanical structure will be ordered soon. Liquid scintillator handling system is being designed. Mock-up detector (~1/4 in length) will be made in June, 2008.

12. Rock sampling (DaeWoo Engineering Co.) Rock samples from boring

13. Rock quality map Near detector site: - tunnel length : 110m - overburden height : 46.1m Far detector site: - tunnel length : 272m - overburden height : 168.1m

14. Stress analysis for tunnel design

16. Detector Design with MC Simulation  Detector performance study & Detector optimization with MC : - Gamma catcher size - Buffer size - photo-sensor coverage (no. of PMTs) - neutron tagging efficiency as a function of Gd concentration  Systematic uncertainty & sensitivity study  Reconstruction(vertex position & energy) program written  Background estimation  RENO-specific MC simulation based on GLG4sim/Geant4 → Detailed detector design and drawings are completed

17. RENO Detector Inner Diameter (cm) Inner Height (cm) Filled withMass (tons) Target Vessel 280320Gd(0.1%) + LS 16.5 Gamma catcher 400440LS30.0 Buffer tank 540580Mineral oil 64.4 Veto tank 840880water352.6 total ~460 tons

18. RENO Detector

19. Electronics  Use SK new electronics (will be ready in Sep., 2008)

20. Source Driving System

21. Prototype Detector Assembly Acrylic vesselsInner acrylic vessel Nitrogen flushing of LS Mounting PMTs Filling with liquid scintillator assembled prototype

22. Mockup Detector Target + Gamma Catcher Acrylic Containers (PMMA: Polymethyl Methacrylate or Plexiglass) TargetDiameter61 cm Height60 cm Gamma Catcher Diameter120 cm Height120 cm BufferDiameter220 cm Height220 cm Buffer Stainless Steel Tank

23. MC of Mockup Detector 60 Co 137 Cs

24. Gd Loaded Liquid Scintillator  Recipe with various mixture: performance ( light yield, transmission & attenuation lengths ), availability, cost, etc.  Design of purification system & flow meter  Long-term stability test  Reaction with acrylic?  R&D on LAB  Recipe of Liquid Scintillator : Aromatic SolventFlourWLSGd-compound LABPPO, BPO Bis-MSB, POPOP 0.1% Gd+TMHA (trimethylhexanoic acid)  0.1% Gd compounds with CBX (Carboxylic acids; R-COOH) - CBX : MVA (2-methylvaleric acid), TMHA (2-methylvaleric acid)

25. Synthesis of Gd-carboxylate precipitation Rinse with 18MΩ water Dryer

26. R&D with LAB Light yield measurement PC100% LAB100% PC40% PC20% LAB100% PC20% N2 LAB60% LAB80% MO80% C n H 2n+1 -C 6 H 5 (n=10~14) High Light Yield : not likely Mineral oil(MO) replace MO and even Pseudocume(PC) probably Good transparency (better than PC) High Flash point : 147 o C (PC : 48 o C) Environmentally friendly (PC : toxic) Components well known (MO : not well known) Domestically available: Isu Chemical Ltd. ( 이수화학 )

27. Measurement of LAB Components with GC-MS C 16 H 26 C 17 H 28 C 18 H 30 C 19 H 32 7.17% 27.63% 34.97% 30.23% LAB : (C 6 H 5 )C N H 2N+1 # of H [m -3 ] = 0.631 x 10 29 H/C = 1.66

28.  Reconstructed vertex:  ~ 8cm at the center of the detector Reconstruction : vertex & energy 1 MeV (KE) e +  Energy response and resolution: visible energy PMT coverage, resolution ~210 photoelectrons per MeV |y|  y (mm) E vis (MeV) y 4 MeV (KE) e +

29. target buffer  -catcher Reconstruction of Cosmic Muons ~140cm ~40cm ~120cm A B C D Veto (OD) Buffer (ID) pulse height time OD PMTs ID PMTs

30. Calculation of Background Rates due to Radioactivity Concentration 40 K (ppb) Concentration 232 Th (ppb) Concentration 238 U (ppb) 40 K [Hz] 232 Th [Hz] 238 U [Hz] Total [Hz] Rock4.33(ppm)7.58(ppm)2.32(ppm)1.067.140.999.19 LS in Target0.001 0.900.090.261.25 Target Contatiner0.0080.050.0080.080.060.030.17 LS in Gamma Catcher0.001 1.520.130.382.03 Gamma Catcher Container 0.0080.050.0080.070.040.030.14 LS in Buffer0.001 0.08 ~ 00.030.11 Buffer Tank0.060.9 0.030.100.200.33 PMT13.6208.549.42.505.232.9910.72 Total~24

31. J μ [cm -2 s -1 ] [GeV] Far 250 m2.9×10 -5 91.7 200 m8.5×10 -5 65.2 Near70 m5.5×10 -4 34.3 Muon intensity at the sea level using modified Gaisser parametrization + MUSIC or Geant4 (the code for propagating muon through rock) Calculation of Muon Rate at the RENO Underground

32. Systematic Errors Systematic SourceCHOOZ (%)RENO (%) Reactor related absolute normalization Reactor antineutrino flux and cross section 1.9< 0.1 Reactor power0.7< 0.1 Energy released per fission0.6< 0.1 Number of protons in target H/C ratio0.80.2 Target mass0.3< 0.1 Detector Efficiency Positron energy0.80.2 Positron geode distance0.10.0 Neutron capture (H/Gd ratio)1.0< 0.1 Capture energy containment0.40.1 Neutron geode distance0.10.0 Neutron delay0.40.1 Positron-neutron distance0.30.0 Neutron multiplicity0.50.05 combined2.7< 0.6

33. RENO Expected Sensitivity 10x better sensitivity than current limit New!! (full analysis)

34. GLoBES group workshop@Heidelberg – Mention’s talk SK  m 2

35. Status Report of RENO  RENO is suitable for measuring  13 (sin 2 (2  13 ) > 0.02)  RENO is under construction phase.  Geological survey and design of access tunnels & detector cavities are completed → Civil construction will begin in early June, 2008.  International collaborators are being invited.  TDR will be ready in June of 2008.  Data –taking is expected to start in early 2010.