Youngdo Oh Pohang University of science and Technology (ydoh@postech.ac.kr)

1. Current Status of RENO NOW2008 (Conca Specchiulla, Italy) Youngdo Oh Pohang University of science and Technology (ydoh@postech.ac.kr)

2. RENO Collaboration (Reactor Experiment for Neutrino Oscillation) • Chonnam National University • Chonpook National University • Dongshin University • Gyeongsang National University • Kyungpook National University • Pusan National University • Sejong University • Seoul National University • Sungkyunkwan University • Pohang University of Science and Technology • Institute of Nuclear Research RAS (Russia) • Institute of Physical Chemistry and Electrochemistry RAS (Russia) +++ 12institutes, 39 members http://neutrino.snu.ac.kr/RENO

3. Yong Gwang Nucleat Power Plant • Located in the west coast of southern part of Korea • ~400km from Seoul • 6 reactors are lined up in roughly equal distances and span ~1.3 km • Total average thermal output ~16.4GWth (2nd largest in the world)

4. Schematic Setup of RENO at YongGwang

5. Google Satellite View of YongGwang Site

6. Experimental Hall Detector Access Tunnel (4m high ☓ 4m wide) Schematic View of Underground Facility Tunnel Detector

7. Schedule 2009 2006 2007 2008 12 12 12 12 3 3 3 3 6 6 6 6 9 9 9 9 Activities Detector Design & Specification Geological Survey & Tunnel Design Detector Construction Excavation & Underground Facility Construction Detector Commissioning We are here

8. Comparison of Reactor Neutrino Experiments

9. Rock sampling (DaeWoo Engineering Co.) Rock samples from boring For chemical composition, density, radioactivity

10. Rock quality map • Far detector site: • tunnel length : 272m • height : 168.1m • Near detector site: • tunnel length : 110m • height : 46.1m

11. Tunnel Design

12. Stress analysis for tunnel design 연속체 안정성 검토 불연속체 안정성 검토 키블럭 안정성 검토 • 터널변위 및 응력해석 • 터널변위 및 응력해석 • 암반 블록파괴 검토 접속부 안정성 검토 확폭 및 수직터널 안정성 검토 콘크리트 구조 검토 • 접속부변위 및 응력해석 • 터널변위 및 응력해석 • 구조물 안정성 검토

13. Tunnel Construction is on going …. On-site office Near tunnel 50m From entrance Power Plant Far tunnel

14. RENO Detector Veto Buffer Target g-catcher • Four concentric cylindrical parts • Identical detectors for near and far • Target and gamma catcher are • filled with liquid scintillator • aiming at detecting inverse beta decay • 342 10-inch PMTs on the surface of buffer • 67 10-inch PMTs on the VETO total ~450 tons

15. Inverse beta decay in RENO Detector γ(0.511MeV) Target : - Gd + LS + e γ(0.511MeV) ν e prompt signal p Gamma catcher : - LS n Delayed signal 30μs γ γ Buffer : - Non scintillating oil Gd å ~ E 8 MeV g γ γ Veto : - Water Shielding : - Steel

16. CAD views of RENO Detector

17. Detector Design with MC Simulation • RENO-specific MC simulation based on GLG4sim/Geant4 •  Detailed detector design and drawings are completed • Detector performance study &Detector optimization with MC: - Gamma catcher size - Buffer size - photo-sensor coverage (numbers of PMTs) - neutron tagging efficiency as a function of Gd concentration • Reconstruction(vertex position & energy) program written • Systematic uncertainty & sensitivity study • Background estimation

18. Systematic Errors Not final, under study

19. RENO Expected Sensitivity

20. SK Dm2 GLoBES group workshop@Heidelberg – Mention’s talk

21. R&D : Liquid scintillator (1) • General Elements of Liquid Scintillator : • PC(20%) + Dodecane(80%) + PPO with bis-MSB or BPO • 0.1% Gd compounds with CBX or BDK • R&D with the Russian INR/IPCE group (Gd powder supply) • 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

22. R&D : Liquid scintillator (2)

23. R&D : Liquid scintillator (3) R&D with LAB instead of PC/PXE + Dodecane CnH2n+1-C6H5 (n=10~14) Light yield measurement • High Light Yield • Good transparency (better than PC) • High Flash point : 147oC (PC : 48oC) • Environmentally friendly (PC : toxic) • Components well known (MO : not well known) • Domestically available: Isu Chemical Ltd.

24. R&D : Liquid scintillator (4) LAB : (C6H5)CNH2N+1 C16H26 C17H28 C18H30 C19H32 7.17% 27.63% 34.97% 30.23% # of H [m-3] = 0.631 x 1029 H/C = 1.66 Measurement of LAB Components with GC-MS N=10 N=11 N=12 N=13

25. R&D : Prototype Detector ( 2007 ) • The prototype detector was bulit • to test properties liquid scintillator • to validate the Monte Carlo Simulation • model based on Geant4

26. Prototype Detector Assembly Acrylic vessels Inner acrylic vessel Mounting PMTs Nitrogen flushing of LS assembled prototype Filling with liquid scintillator

27. R&D : Mockup Detector ( 1 ) • By building mockup detector, we will answer the technical questions for final design of • main detector. • ~40% scale to the main detector in size and 31 10-inch PMTs • To test • Fabrication in Sepember 2008 • Data taking from October 2008, for next 6 months diameter height Target 60cm 60cm Gamma catcher 120cm 120cm Buffer 220cm 220cm • - long tem stability and light transmittance of acrylic tank • - source and light calibration • PMT performance in mineral oil • liquid handling system • daq and data manipulation

28. R&D : Mockup Detector ( 2 ) • PMT installation is done last week. • DAQ and HV system ready • Calibration system (this week) • LS filling from next week • Data taking from October for 6 months

29. R&D : Mockup Detector ( 3 ) Source and light calibration system : 137Cs, 60Co, 22Na, 252Cf , LED LED LED Trigger LED Trigger Pulse generator Pulse generator Diffuse ball LED Trigger Pulse generator Liquid handling system DAQ for mockup – 400MHz FADC

30. R&D : Mockup Detector ( 4 ) • Geant4 Monte Calro Simulation Energy response of the mockup to the 137Cs(left) 60Co(right) at the center of the detector Energy linearity (left) and energy resolution(right) for positron

31. Status Report of RENO • RENO is suitable for measuring q13 (sin2(2q13) > 0.02) • Geological survey and design of access tunnels & detector cavities are completed → Excavation started • RENO is under construction phase. • Data –taking is expected to start in early 2010. • Mockup detector will operate soon. • International collaborators are being invited.

32. Back up slide

33. Principle of Neutrino Detection Prompt • Use inverse beta decay (ve + p e+ + n) reaction process • Prompt part: subsequent annihilation of the positron to two 0.511MeV  • Delayed part: neutron is captured ~200ms w/o Gd ~ 30ms w Gd Gd has largest n absorption cross section & emits high energy g • Signal from neutron capture ~2.2MeV w/o Gd ~ 8MeV w Gd • Measure prompt signal & delayed signal • “Delayed coincidence” reduces backgrounds drastically Delayed

34. Gamma catcher thickness = 20cm Gamma catcher thickness = 90cm Gd capture H capture MeV MeV MeV Study on -catcher size RENO 70cm: (94.28+/-0.54)% 60cm: (92.98+/-0.56)% Daya Bay 45cm: 92% Chooz 70cm: (94.6+/-0.4)%

35. 4 MeV(KE) e+ y sy (mm) |y| Evis (MeV) 1 MeV (KE) e+ PMT coverage, resolution ~210 photoelectrons per MeV visible energy Reconstruction : vertex & energy • Reconstructed vertex:~8cm at the center of the detector • Energy response and resolution:

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

37. Calculation of Muon Rate at the RENO Underground Muon intensity at the sea level using modified Gaisser parametrization + MUSIC or Geant4 (the code for propagating muon through rock)

38. Calculation of g Background at the RENO Underground • g rate from rock [Hz]

39. Efforts for On-site Facility • 03~08, 2006 : Project description to local government, residents, and NGO’s (endorsed by local government) • 03, 2007 : Agreement between KHNP and SNU • 03~10, 2007 : Geological survey and tunnel design are completed. • 12, 2007 : Public hearing for YG residents • 01, 2008 : Safety regulation established and accepted by the atomic energy department of MOST • 05~11, 2008 : Tunnel construction